place a breakpoint on line 13
#I need help with a Project for class
deep ravine
run in debug mode
it should pause/suspend the app once execution has reached your breakpoint
left tartan
wait so it's nto already in debug mode?
deep ravine
it was
left tartan
it just copied something
deep ravine
you just arent using it properly
left tartan
deep ravine
place a breakpoint
left tartan
place a breakpoint
how
left tartan
i thought debugging ur code was just manually finding all the stuff u were missing urself
what do u do with breakpoint
i'm gonna try deleting it
the debug thingy
and click it again
left tartan
ok
alright so after putting the breakpoint on there, u go to window, run
and then dubug
sorry not window
just run
and then debug
thats supose to say line 13 isn't it
i clicked enable breakpoint
uncut marsh
i clicked enable breakpoint
in debug mode there is something like step over
maybe its different on your ide
but if you click it it goes line by line
left tartan
ok we just went over nodes today
no polumoriigism
just continued this today in class
right anyways
left tartan
in debug mode there is something like step over
ok where do u usuualy go
i got no idea what i'm clciking
hold on i ma search it up
i'll be back
uncut marsh
ok where do u usuualy go
left tartan
Ok lemme see if I can find something like that on eclipse
Bruh I asked the professor and he’s like we’ll learn about debugging in eclipse in the future lecture 💀
uncut marsh
Bruh I asked the professor and he’s like we’ll learn about debugging in eclipse ...
well for now lets make another loop in readfile
this is what you have ```java
import java.util.Arrays;
import javax.swing.*;
public class Project1 {
public static void main (String[] args) {
readfile();
Arrays.toString(arr);
System.out.println(Arrays.toString(arr));
}
public static Appliance [] arr;
public static void readfile (){
String filename = "Project1.txt";
TextFileInput in = new TextFileInput(filename);
String line;
int count = in.getLineCount() +1 ;
arr = new Appliance[count];
while ((line = in.readLine()) != null){
arr[count] = new Appliance(line);
count --;
}
in.close();
}
}```
left tartan
Yeah I ma just figure the debug thing later
uncut marsh
make count start in 0
int count = 0;
just after the count, and before the array, create another while loop
while ((line = in.readLine()) != null){
}```and there you put count++;
left tartan
Alright I’ll get to that
I’m about to go home rn so I’m in the bus, I’ll continue this when I’m home, I’ll be back later
left tartan
```java
while ((line = in.readLine()) != null){
}```
u said another
so that first one stays?
left tartan
alright
left tartan
import java.util.Arrays;
import javax.swing.*;
public class Project1 {
public static void main (String[] args) {
readfile();
Arrays.toString(arr);
System.out.println(Arrays.toString(arr));
}
public static Appliance [] arr;
public static void readfile (){
String filename = "Project1.txt";
TextFileInput in = new TextFileInput(filename);
String line;
int count = 0;
while ((line = in.readLine()) != null){
count++;
}
in = new TextFileInput(filename);
int count = in.getLineCount() +1 ;
arr = new Appliance[count];
while ((line = in.readLine()) != null){
arr[count] = new Appliance(line);
count --;
}
in.close();
}
}```it should be in this order
- declare count
- the loop with count++
- in = new TextFileInput(filename); // to reset the line buffer
- declare the array with new Appliance[count];
- the loop filling the array
left tartan
wait so that loop i just created should be before the other loop
uncut marsh
wait so that loop i just created should be before the other loop
yes
left tartan
import java.util.Arrays;
import javax.swing.*;
public class Project1 {
public static void main (String[] args) {
readfile();
Arrays.toString(arr);
System.out.println(Arrays.toString(arr));
}
public static Appliance [] arr;
public static void readfile (){
String filename = "Project1.txt";
TextFileInput in = new TextFileInput(filename);
String line;
int count = 0;
while ((line = in.readLine()) != null){
count++;
}
in = new TextFileInput(filename);
arr = new Appliance[count];
while ((line = in.readLine()) != null){
count --;
arr[count] = new Appliance(line);
}
in.close();
}
}```delete this: int count = in.getLineCount() +1 ;
now put the count-- before arr[count] in second loop
now it should work
left tartan
lets index 20 out of bounds for lenght 20
left tartan
now put the count-- before arr[count] in second loop
alrigt hold on
cause i ran it without out that
lets see
oo it prints
horizontal lol
a simple /n should do
left tartan
yea thats good
uncut marsh
now we have to create the GUI
left tartan
right
first though
i may be overthinking this but
how does the program know when to add a comma
uncut marsh
how does the program know when to add a comma
This is what Arrays.toString() does
[a, b, c]
uncut marsh
does your professor let you send many .java files?
left tartan
ye he said to submit two
uncut marsh
only two?
left tartan
ye
uncut marsh
damn
left tartan
uncut marsh
the code will look ugly but its what we have
left tartan
because the textfileinput
he has it already
so we dont have to submit it
same thing with any other file he gave us
txt file that is
uncut marsh
by the way
left tartan
ye
left tartan
like everything in one file?
i used to think it worked like that until a few days ago
where i discovrerd u can use code form other files
uncut marsh
anyways
uncut marsh
we can proceed in two ways
- create the JFrame in Main and do the stuff
- create a new class that extends JFrame
left tartan
first one 💀
left tartan
to main?
uncut marsh
yes
left tartan
import java.util.Arrays;
import javax.swing.*;
public class Project1 {
public static void main extends JFrame(String[] args) {
readfile();
Arrays.toString(arr);
System.out.println(Arrays.toString(arr));
}
public static Appliance [] arr;
public static void readfile (){
String filename = "Project1.txt";
TextFileInput in = new TextFileInput(filename);
String line;
int count = 0;
while ((line = in.readLine()) != null){
count++;
}
in = new TextFileInput(filename);
arr = new Appliance[count];
while ((line = in.readLine()) != null){
count --;
arr[count] = new Appliance(line);
}
in.close();
}
}```uh
uncut marsh
```java
import java.util.Arrays;
import javax.swing.*;
public class Project1 {
...
oh no
I forgot that your class is Project1
put the extends after Project1
not in main method
left tartan
so i write extend in applaince
uncut marsh
so i write extend in applaince
no, here
uncut marsh
idk I don't use eclipse
left tartan
i ma just cancel
uncut marsh
continue
uncut marsh
it doesn't look like it did anything
so it works
left tartan
so it works
it accepted the qualitites of the Jframe object im assuming?
left tartan
import java.util.Arrays;
import javax.swing.*;
public class Project1 extends JFrame {
public static void main (String[] args) {
readfile();
Arrays.toString(arr);
System.out.println(Arrays.toString(arr));
}
public static Appliance [] arr;
public static void readfile (){
String filename = "Project1.txt";
TextFileInput in = new TextFileInput(filename);
String line;
int count = 0;
while ((line = in.readLine()) != null){
count++;
}
in = new TextFileInput(filename);
arr = new Appliance[count];
while ((line = in.readLine()) != null){
count --;
arr[count] = new Appliance(line);
}
in.close();
}
public static void MakeGUI() {
Project1 gui = new Project1();
gui.setTitle("Appliances");
gui.setSize(640, 480);
gui.setLocationRelativeTo(null);
gui.setVisible(true);
}
}```now put this:
Project1 gui = new Project1();
gui.setTitle("Appliances");
gui.setSize(640, 480);
gui.setLocationRelativeTo(null);
gui.setDefaultCloseOperation(EXIT_ON_CLOSE);
gui.setVisible(true);```Ask me if you have questionsok so
main gui?
what is Main Gui
its uppercase
so maybe its not the the main method
left tartan
ohhh alright
now that makes sense
cause it extends that class
alright so as for the rest
U seem to be doing that
uncut marsh
yeah I forgot the close operation
uncut marsh
```java
gui.setLocationRelativeTo(null);```
The target screen mentioned below is a screen to which the window should be placed after the setLocationRelativeTo method is called.
If the component is null, or the GraphicsConfiguration associated with this component is null, the window is placed in the center of the screen. The center point can be obtained with the GraphicsEnvironment.getCenterPoint method.```it puts the window on the center
uncut marsh
yes
left tartan
ok so
import java.util.Arrays;
import javax.swing.*;
public class Project1 extends JFrame {
public static void main (String[] args) {
readfile();
Arrays.toString(arr);
System.out.println(Arrays.toString(arr));
}
public static Appliance [] arr;
public static void readfile (){
String filename = "Project1.txt";
TextFileInput in = new TextFileInput(filename);
String line;
int count = 0;
while ((line = in.readLine()) != null){
count++;
}
in = new TextFileInput(filename);
arr = new Appliance[count];
while ((line = in.readLine()) != null){
count --;
arr[count] = new Appliance(line);
}
in.close();
}
public static void MakeGUI() {
Project1 gui = new Project1();
gui.setTitle("Appliances");
gui.setSize(640, 480);
gui.setLocationRelativeTo(null);
gui.setVisible(true);
gui.setDefaultCloseOperation(EXIT_ON_CLOSE);
}
}```lets see
setTitle
i can't code this i should draw it
uncut marsh
put gui.setDefaultCloseOperation(EXIT_ON_CLOSE); before setVisible
else it wont actually close the program if you click the x
uncut marsh
what does that do
if you don't put that the window doesn't show at all
left tartan
ok size obiosuly the windth and hegiht of box
title probably shows up on the top
ok so rn
i wonder if i can use the whiteboard here
damn i can't 💀
ok i'll draw
gimme 1 minute
uncut marsh
we probably need a JTable
uncut marsh
yeah
left tartan
thats in the main then still right
uncut marsh
public Project1() {
}```in Project1 class
left tartan
oh the class file
uncut marsh
like we did in Appliances before
left tartan
the capital c is the class but
wait i just make another function don't i?
cause readfile
makegui
are funtions
and they are under class
uncut marsh
wait i just make another function don't i?
that too
but with the constructor is simpler
or non-static method
left tartan
import java.util.Arrays;
import javax.swing.*;
public class Project1 extends JFrame {
public static void main (String[] args) {
readfile();
Arrays.toString(arr);
System.out.println(Arrays.toString(arr));
}
public static Appliance [] arr;
public static void readfile (){
String filename = "Project1.txt";
TextFileInput in = new TextFileInput(filename);
String line;
int count = 0;
while ((line = in.readLine()) != null){
count++;
}
in = new TextFileInput(filename);
arr = new Appliance[count];
while ((line = in.readLine()) != null){
count --;
arr[count] = new Appliance(line);
}
in.close();
}
public static void MakeGUI() {
Project1 gui = new Project1();
gui.setTitle("Appliances");
gui.setSize(640, 480);
gui.setLocationRelativeTo(null);
gui.setVisible(true);
gui.setDefaultCloseOperation(EXIT_ON_CLOSE);
}
public Project1() {
}
}```right cause Project1 is a class afterall
just like applaince
its just that it happens to contain a main method
i think
ok so this contructor is making the gui compenets
don't the gui compenets come with JFrame?
uncut marsh
don't the gui compenets come with JFrame?
the gui components are added to JFrame
deep ravine
dont make your class extend JFrame
uncut marsh
like .add()
deep ravine
multiple reasons why, the biggest being "too many problems occur when beginners do that"
left tartan
when we can just make something do the stuff jframe has
deep ravine
the more powerful reason is that extends defines a relationship
an "is-a" relationship
your program is not a frame. it uses a frame
Program is a JFrame.. its not really just a frame, its an entire program
which uses a frame
i would say Program is NOT a JFrame. your class is not trying to extend the features that a frame has. it is not a frame
it uses one
other apps cannot use Program as a frame
left tartan
i don't mind doing that but i think i'm supose to entend it just from this since he went over entends
though i supose it doesn't really specifiy
uncut marsh
though i supose it doesn't really specifiy
You can do as Dioxin says, you just have to type more
deep ravine
look at what it says, VS what you are doing
left tartan
u mean since it says Create a GUI, we create the class for it
deep ravine
the entire program shouldnt exist there
uncut marsh
That's why I would make a different class for the GUI
deep ravine
what they are showing is not good use of inheritance. but at least its labeled a bit better
do what you gotta do. if its a requirement, then do it
uncut marsh
But since professor only lets OP to send two files, we would have to put another class in the same .java file
left tartan
alright
deep ravine
"lets use extend so we dont have to code as much"
tons of papers documenting why that is bad
but that seems to be the route your assignment wants
deep ravine
just dont do it on your own accord
didnt realize it was an actual requirement for your assignment
i thought we were past that phase, of misusing extends
sorry to distract from your issue
astral glen
didnt realize it was an actual requirement for your assignment
And then we wonder why entire languages discarded inheritance to prevent people from misusing it 
left tartan
import java.util.Arrays;
import javax.swing.*;
public class Project1 extends JFrame {
public static void main (String[] args) {
readfile();
Arrays.toString(arr);
System.out.println(Arrays.toString(arr));
}
public static Appliance [] arr;
public static void readfile (){
String filename = "Project1.txt";
TextFileInput in = new TextFileInput(filename);
String line;
int count = 0;
while ((line = in.readLine()) != null){
count++;
}
in = new TextFileInput(filename);
arr = new Appliance[count];
while ((line = in.readLine()) != null){
count --;
arr[count] = new Appliance(line);
}
in.close();
}
public static void MakeGUI() {
Project1 gui = new Project1();
gui.setTitle("Appliances");
gui.setSize(640, 480);
gui.setLocationRelativeTo(null);
gui.setVisible(true);
gui.setDefaultCloseOperation(EXIT_ON_CLOSE);
}
public Project1() {
}
private Jtable(){
}
}```rn, we have a panel
deep ravine
And then we wonder why entire languages discarded inheritance to prevent people ...
even James Gosling had some heat against it being introduced in Java, due to things like this
left tartan
and we just need to add three different ones in there
uncut marsh
whats your current issue? to get things back on-topic
just to separate the types and putting the elements in a JTable
uncut marsh
and we just need to add three different ones in there
create a private JTable
left tartan
so uhm whats a Jtable
uncut marsh
wait within public project1?
outside
left tartan
import java.util.Arrays;
import javax.swing.*;
public class Project1 extends JFrame {
public static void main (String[] args) {
readfile();
Arrays.toString(arr);
System.out.println(Arrays.toString(arr));
}
public static Appliance [] arr;
public static void readfile (){
String filename = "Project1.txt";
TextFileInput in = new TextFileInput(filename);
String line;
int count = 0;
while ((line = in.readLine()) != null){
count++;
}
in = new TextFileInput(filename);
arr = new Appliance[count];
while ((line = in.readLine()) != null){
count --;
arr[count] = new Appliance(line);
}
in.close();
}
public static void MakeGUI() {
Project1 gui = new Project1();
gui.setTitle("Appliances");
gui.setSize(640, 480);
gui.setLocationRelativeTo(null);
gui.setVisible(true);
gui.setDefaultCloseOperation(EXIT_ON_CLOSE);
}
public Project1() {
}
private Jtable table;
}```no
uncut marsh
not a function
left tartan
ye
uncut marsh
private JTable table;
left tartan
so just privite Jtable
ok so Jtable acts like a datatype
and table is the varible?
uncut marsh
and table is the varible?
yes
left tartan
like java private String SRN;
ok
so that table could be named tree and its fine then
ok moving on
Jtable , is that built in?
uncut marsh
lets make a function that returns a two dimensional array
uncut marsh
Jtable , is that built in?
yes
left tartan
oh ok so it'll make a table for us for anything
uncut marsh
lets make a function that returns a two dimensional array
This will be the content of the table
left tartan
i see
uncut marsh
so
left tartan
ok so arr could be box
left tartan
import java.util.Arrays;
import javax.swing.*;
public class Project1 extends JFrame {
public static void main (String[] args) {
readfile();
Arrays.toString(arr);
System.out.println(Arrays.toString(arr));
}
public static Appliance [] arr;
public static void readfile (){
String filename = "Project1.txt";
TextFileInput in = new TextFileInput(filename);
String line;
int count = 0;
while ((line = in.readLine()) != null){
count++;
}
in = new TextFileInput(filename);
arr = new Appliance[count];
while ((line = in.readLine()) != null){
count --;
arr[count] = new Appliance(line);
}
in.close();
}
public static void MakeGUI() {
Project1 gui = new Project1();
gui.setTitle("Appliances");
gui.setSize(640, 480);
gui.setLocationRelativeTo(null);
gui.setVisible(true);
gui.setDefaultCloseOperation(EXIT_ON_CLOSE);
}
public Project1() {
}
private Jtable table;
static Appliance[][] getTableArray() {
Appliance[] refrigerators = new Appliance[arr.length];
Appliance[] dishwashers = new Appliance[arr.length];
Appliance[] microwaves = new Appliance[arr.length];
}
}```no, no
that thing we will make it in a function
so we don't fill the constructor
so
static Appliance[][] getTableArray() {
}```there we will create 3 arrays with the same length as arr
Appliance[] refrigerators = new Appliance[arr.length];
left tartan
oh and the other names
uncut marsh
for every kind of appliance
uncut marsh
after that make a for loop that iterates from zero to arr.length
left tartan
when i think about it makes sense, we need an array of appliances
left tartan
after that make a for loop that iterates from zero to arr.length
alright
uncut marsh
yeah for every column
uncut marsh
oh right
left tartan
each one?
uncut marsh
the assignment tells you to order them
left tartan
yeah
both inside and with the letters i think
i forgot what selection sort did
we have the code for it he gave it to us
uncut marsh
we have the code for it he gave it to us
yeah make a function to sort arr
uncut marsh
alright so
we will use compareTo for this
left tartan
private Jtable table;
static Appliance[][] getTableArray() {
Appliance[] refrigerators = new Appliance[arr.length];
Appliance[] dishwashers = new Appliance[arr.length];
Appliance[] microwaves = new Appliance[arr.length];
}
public SelectionsSort(){
}```remember that method you added to Appliance
left tartan
ye
public class Appliance {
private String SRN;
public Appliance (String SRN) {
this.SRN = SRN;
}
@Override
public String toString() {
return SRN;
}
public int compareTo (Appliance x) {
return this.SRN.compareTo(x.SRN);
}
public boolean equals(Appliance y) {
return this.SRN.equals(y.SRN);
}
public char convert(){
return SRN.charAt(0);
}
public String getSRN() {
return SRN;
}
public void setSRN(String SRN) {
this.SRN = SRN;
}
}```so it comares the numbers
and returns
actaully
how do we know what it returns
if it returns the bigger one
or smller one
uncut marsh
if it returns the bigger one
if you use eg e1.compareTo(e2)
it will give either a negative or positive number if they are different
and 0 if they're equal
left tartan
im assuming the lowest goes on top
uncut marsh
sorted by what
yeah it doesn't tell
uncut marsh
im assuming the lowest goes on top
the safest bet
left tartan
cause in class
he did it that way
ok so its swap after the compareTo
public SelectionsSort(){
Appliance.compareTo
}```ok hold on
since its in the class
we call it from applaince right
yeah im just gonna go for it
but it takes one parameter
left tartan
are we comparing one array to another?
uncut marsh
are we comparing one array to another?
one element of the array to another
left tartan
i thought it was inside one array and sort it then move on to the next array
i misread it then
it chekcs the first letter
uncut marsh
i thought it was inside one array and sort it then move on to the next array
It's simpler to just sort the large array, and split it after in the three ones in the table array
left tartan
and see's which array it goes into right?
uncut marsh
copy the selection sort code
left tartan
It's simpler to just sort the large array, and split it after in the three ones ...
so after all three arrasy have the right thingys
uncut marsh
copy the selection sort code
I will tell you what to do after
left tartan
okie
lemme copy paste it
private static void selectionSort(short[] array, int length) {
for ( int i = 0; i < length - 1; i++ ) {
int indexLowest = i;
for ( int j = i + 1; j < length; j++ ){
if (array[j].compareTo(array[indexLowest]) < 0)
indexLowest = j;
if ( array[indexLowest] != array[i] ) {
short temp = array[indexLowest];
array[indexLowest] = array[i];
array[i] = temp;
} // if
} // for i
} // method selectionSort
kind pathBOT
```java
private static void selectionSort(short[] array, int length) {
for ( i...
Detected code, here are some useful tools:
uncut marsh
if (array[j] < array[indexLowest])```becomes```java
if (array[j].compareTo(array[indexLowest]) < 0)```it looks like a basic selection sort, written using imperative code
welcome to programming
left tartan
no i meant when it wasn't indented lol
deep ravine
ah
left tartan
it looked crazy
deep ravine
the indentation is a personal thing
you used 2 spaces
thats the Google standard
the usual Java standard is 4 spaces. either way, it looks the same to me
uncut marsh
if ( array[indexLowest] != array[i] )```to```java
if ( !array[indexLowest].equals(array[i]) )```private static void selectionSort(short[] array, int length) {
for ( int i = 0; i < length - 1; i++ ) {
int indexLowest = i;
for ( int j = i + 1; j < length; j++ ){
if (arr[j].compareTo(arr[indexLowest]) < 0)
indexLowest = j;
if ( !arr[indexLowest].equals(arr[i]) ) ) {
short temp = arr[indexLowest];
arr[indexLowest] = arr[i];
arr[i] = Appliance temp;
} // if
} // for i
} // method selectionSort```this too
deep ravine
please learn how to use the debugger.. its built for situations like this
to pinpoint logic issues
you can solve problems like this on your own pretty easily, once you know where the issue is - debuggers do just that, help you pinpoint where the problem is
uncut marsh
```java
private static void selectionSort(short[] array, int length) {
for ( i...
the temp variable
declare it as Appliance type
and rename array to arr
left tartan
like appliance temp?
uncut marsh
I think that's all
left tartan
not just the function name
left tartan
public static void SelectionsSort(){
for ( int i = 0; i < arr.length - 1; i++ ) {
int indexLowest = i;
for ( int j = i + 1; j < arr.length; j++ ){
if (arr[j].compareTo(arr[indexLowest]) < 0)
indexLowest = j;
if ( !arr[indexLowest].equals(arr[i]) ) ) {
short temp = arr[indexLowest];
arr[indexLowest] = arr[i];
arr[i] = temp;
} // if
} // for i
}```good
last thing
we can delete the parameters
since arr is static
and instead of length you can use arr.length
make SelectionsSort() static
so everyone can use it
and void type
like
public static void
left tartan
what about the short
uncut marsh
ah
short temp = arr[indexLowest];
temp should be Appliance
remove the one at the top, I thought it wasnt declared
left tartan
ok
left tartan
public static void SelectionsSort(){
for ( int i = 0; i < arr.length - 1; i++ ) {
int indexLowest = i;
for ( int j = i + 1; j < arr.length; j++ ){
if (arr[j].compareTo(arr[indexLowest]) < 0) {
indexLowest = j;
}
if ( !arr[indexLowest].equals(arr[i]) ) {
short temp = arr[indexLowest];
arr[indexLowest] = arr[i];
arr[i] = temp;
} // if
} // for i
}
}```wh is temp red
uncut marsh
at the beginning
left tartan
if its declared asa short
uncut marsh
```java
public static void SelectionsSort(){
for ( int i = 0; i < arr.le...
should be Appliance
not short
left tartan
lemme remove short then and change it
uncut marsh
the old exercise you were working with a short[] array
left tartan
the Jtable is red too 💀
private Jtable table;
static Appliance[][] getTableArray() {
SelctionsSort();
Appliance[] refrigerators = new Appliance[arr.length];
Appliance[] dishwashers = new Appliance[arr.length];
Appliance[] microwaves = new Appliance[arr.length];
}```ohh
uncut marsh
before refrigerators
call SelectionsSort
and it will be sorted
of after
i don't think it matters
then let's make a for loop
left tartan
private Jtable table;
static Appliance[][] getTableArray() {
SelectionSort();
Appliance[] refrigerators = new Appliance[arr.length];
Appliance[] dishwashers = new Appliance[arr.length];
Appliance[] microwaves = new Appliance[arr.length];
}
public static void SelectionSort(){
for ( int i = 0; i < arr.length - 1; i++ ) {
int indexLowest = i;
for ( int j = i + 1; j < arr.length; j++ ){
if (arr[j].compareTo(arr[indexLowest]) < 0) {
indexLowest = j;
}
if ( !arr[indexLowest].equals(arr[i]) ) {
Appliance temp = arr[indexLowest];
arr[indexLowest] = arr[i];
arr[i] = temp;
} // if
} // for i
}
}```yk from 0 to arr.length
left tartan
yeah first forloop
left tartan
we haven't learned switches
uncut marsh
we haven't learned switches
then ifs
uncut marsh
do you have getType right?
left tartan
ok but ur saying write the if to compare letters?
uncut marsh
in Appliance
uncut marsh
ok but ur saying write the if to compare letters?
yes
left tartan
public class Appliance {
private String SRN;
public Appliance (String SRN) {
this.SRN = SRN;
}
@Override
public String toString() {
return SRN;
}
public int compareTo (Appliance x) {
return this.SRN.compareTo(x.SRN);
}
public boolean equals(Appliance y) {
return this.SRN.equals(y.SRN);
}
public char convert(){
return SRN.charAt(0);
}
public String getSRN() {
return SRN;
}
public void setSRN(String SRN) {
this.SRN = SRN;
}
}```getsrn
uncut marsh
i thought parse
you can name it what you want
left tartan
u mean its not built in
uncut marsh
we need that functionality that returns the first letter
uncut marsh
so we can do like this:
if (arr[i].convert() == 'R') refrigerators[r] = arr[i];
left tartan
i just relaized we have a convert method
uncut marsh
show what you have done until now
left tartan
so we can do like this:
if (arr[i].convert() == 'R') refrigerators[r] = arr[i];
wait these goes in above the selection sort?
or in there
uncut marsh
wait these goes in above the selection sort?
in the loop we make at the bottom of the function
but you will add the counter
this
if (arr[i].convert() == 'R') {
refrigerators[r] = arr[i];
r++;
}```and for every type
left tartan
private Jtable table;
static Appliance[][] getTableArray() {
SelectionSort();
Appliance[] refrigerators = new Appliance[arr.length];
Appliance[] dishwashers = new Appliance[arr.length];
Appliance[] microwaves = new Appliance[arr.length];
int r = 0, d = 0, m = 0;
for(int i = 0 i < arr.length;i++){
if (arr[i].convert() == 'R') {
refrigerators[r] = arr[i];
r++;
}
if (arr[i].convert() == 'D') {
dishwashers[d] = arr[i];
d++;
}
if (arr[i].convert() == 'M') {
microwaves[m] = arr[i];
m++;
}
}
}
}
public static void SelectionSort(){
for ( int i = 0; i < arr.length - 1; i++ ) {
int indexLowest = i;
for ( int j = i + 1; j < arr.length; j++ ){
if (arr[j].compareTo(arr[indexLowest]) < 0) {
indexLowest = j;
}
if ( !arr[indexLowest].equals(arr[i]) ) {
Appliance temp = arr[indexLowest];
arr[indexLowest] = arr[i];
arr[i] = temp;
} // if
} // for i
}
}```the count, its okay there?
uncut marsh
```java
private Jtable table;
static Appliance[][] getTableArray() {
Sel...
Not in selection sort 💀
left tartan
that has all the if statements?
uncut marsh
too many fors right ☠️
left tartan
yea
uncut marsh
that has all the if statements?
yes
left tartan
but ye
private Jtable table;
static Appliance[][] getTableArray() {
SelectionSort();
Appliance[] refrigerators = new Appliance[arr.length];
Appliance[] dishwashers = new Appliance[arr.length];
Appliance[] microwaves = new Appliance[arr.length];
int r = 0, d = 0, m = 0;
for(int i = 0 i < arr.length;i++){
if (arr[i].convert() == 'R') {
refrigerators[r] = arr[i];
r++;
}
if (arr[i].convert() == 'D') {
dishwashers[d] = arr[i];
d++;
}
if (arr[i].convert() == 'M') {
microwaves[m] = arr[i];
m++;
}
}
return new Appliance[][]{refrigerators, dishwashers. microwaves};
}
}
public static void SelectionSort(){
for ( int i = 0; i < arr.length - 1; i++ ) {
int indexLowest = i;
for ( int j = i + 1; j < arr.length; j++ ){
if (arr[j].compareTo(arr[indexLowest]) < 0) {
indexLowest = j;
}
if ( !arr[indexLowest].equals(arr[i]) ) {
Appliance temp = arr[indexLowest];
arr[indexLowest] = arr[i];
arr[i] = temp;
} // if
} // for i
}
}```right this is all under the appliance srray thingy
uncut marsh
return new Appliance[][]{refrigerators, dishwashers, microwaves};
left tartan
after for loop right
left tartan
after the for loop
ye
uncut marsh
tell me if there's any errors
left tartan
oh right lemme put that all back in ecipse
just bene editing here
ah it didn't compile
the Jtable thing is red
private Jtable table;
static Appliance[][] getTableArray() {
SelectionSort();
Appliance[] refrigerators = new Appliance[arr.length];
Appliance[] dishwashers = new Appliance[arr.length];
Appliance[] microwaves = new Appliance[arr.length];```ye
well it printed
just not sorted
btw how do u make it print vertical
then i screenshot it
left tartan
alright
left tartan
just where the main is right
left tartan
public static void main (String[] args) {
readfile();
Arrays.toString(arr);
SelectionSort();
System.out.println(Arrays.toString(arr));
for (int i =0; i < arr.length; i++) {
Appliance a = arr[i];
}
}```i have questions actaully ebfore i do that
uncut marsh
ok
left tartan
for (Appliance a : arr) {
}
what is that for loop
left tartan
no i mean there isn't any iteranting
uncut marsh
like Lists
left tartan
or stoping
uncut marsh
no i mean there isn't any iteranting
there are, is just invisible
it's like a shorter way to write a for loop
left tartan
so it would in reality be for(Appliance a =0;a < arr.length ;a++)?
uncut marsh
so it would in reality be for(Appliance a =0;a < arr.length ;a++)?
more like: java for (int i =0; i < arr.length; i++) { Appliance a = arr[i]; }
just hidden
left tartan
oh no appliance ok
wait so i do that 2 more times
how does it know which array i'm talking about though
left tartan
oh ok
idk why it took so long to register that we techincially have 4 arrays
so the big one
we just print it now
uncut marsh
yeah run the code
left tartan
public static void main (String[] args) {
readfile();
Arrays.toString(arr);
SelectionSort();
for (int i =0; i < arr.length; i++) {
Appliance a = arr[i];
System.out.println(a);
}
}```why you didn't use the for each 😭
anyways its the same
deep ravine
why did you call Arrays.toString twice?
uncut marsh
```java
public static void main (String[] args) {
readfile();
Arrays...
since we are no longer printing the array horizontally, we don't need them
you can delete
deep ravine
we aim to help you understand. not just solve the problem you currently have, but to actually understand the code
left tartan
oh right with just that, it prints horizontally
deep ravine
that way you wont be back with the same problems
left tartan
public static void main (String[] args) {
readfile();
Arrays.toString(arr);
SelectionSort();
for (int i =0; i < arr.length; i++) {
Appliance a = arr[i];
System.out.println(a);
}
}```now it prints like
deep ravine
Crystal, if theres any code you dont understand, please ask. don't just use code that you dont know
left tartan
yeah thats why i've jsut been asking questions
deep ravine
```java
public static void main (String[] args) {
readfile();
Ar...
line 3, whats that doing?
left tartan
u mean the selectionsort?
deep ravine
Arrays.toString(arr)
left tartan
it's has the array of the appliacnes
uncut marsh
no
left tartan
but when u print it
uncut marsh
the name its clear
deep ravine
thats very very far
deep ravine
right now, its doing nothing. its dead code
left tartan
so it's not being used
deep ravine
exactly. your IDE should be flagging you for it, with a warning
left tartan
shouldn't i delete it
uncut marsh
you should
left tartan
uncut marsh
it wont crash or anything but its a recommendation
deep ravine
however, Arrays.toString may be useful. you just gotta understand it properly, so you dont misuse it
thats what i mean, about understanding the code
otherwise, itll take longer to solve whatever problems you have, simply cause you arent familiar with what you got
left tartan
okay
deep ravine
#today-i-teach message
dont just use code thats given to you
do you understand readFile()?
deep ravine
do you understand SelectionSort()?
left tartan
everytime u call it
u put the readfile in a loop
u can make it read the whole file
line by line
deep ravine
right on, where is that data stored in your app?
which variable references those lines you read?
how does this data get passed to SelectionSort()?
left tartan
actaully i'm not sure if it sorted
uncut marsh
it sorted well
deep ravine
nemux says it works. you arent sure. thats the problem
you need to be sure. nemux cant be the only one who is sure
left tartan
left tartan
oh its sorting by the first letter first for the smllest
right they never said anything about numbers
ok so that means now we have to find a way to sort into arrays
based on their letter
mrm
deep ravine
are you sorting the lines?
left tartan
deep ravine
whats the assignment?
uncut marsh
strange
left tartan
public class Appliance {
private String SRN;
public Appliance (String SRN) {
this.SRN = SRN;
}
@Override
public String toString() {
return SRN;
}
public int compareTo (Appliance x) {
return this.SRN.compareTo(x.SRN);
}
public boolean equals(Appliance y) {
return this.SRN.equals(y.SRN);
}
public char convert(){
return SRN.charAt(0);
}
public String getSRN() {
return SRN;
}
public void setSRN(String SRN) {
this.SRN = SRN;
}
}```right on, equals is a bit weak, but that shouldn't be a big deal. you created a blueprint. do you understand everything there?
left tartan
yeaah
deep ravine
equals actually wont work
you arent overriding it properly
put the @Override annotation on it, like you did with toString()
left tartan
deep ravine
thats a good thing
its pointing out that you messed up
you are trying to override. but you didnt
remember, equals and toString are defined in Object
left tartan
object.equals?
deep ravine
these are JavaDocs. a bit scary at first, but youll grow to love them
this shows the definition of equals
its equals(Object)
not equals(Application)
so yeah, your code is not overriding, when it should. thats what the squiggly was telling you
deep ravine
thats still an error
look at y
Object Appliance y doesnt make sense
this is what i meant by "you gotta understand the code"
left tartan
but appliance is the datatype
deep ravine
not here
deep ravine
you are overriding an existing method
that method is defined in Object. all classes extend Object
and Object has no clue about Appliance type
uncut marsh
you have to check that the object is an appliance
deep ravine
yup, thats one of the things they should do in equals
but they arent even there yet
if they keep making mistakes like this, itll take 2 generations to solve this relatively simple problem
imagine how long a large app would take
they gotta understand the code. these are the fundementals, the building blocks
deep ravine
remove Appliance
the () part is where the "parameters" are defined
know what parameters are?
left tartan
ok remove appliance
deep ravine
but why?
left tartan
but then how will it know i'm talking about it
left tartan
and whats that
deep ravine
Application is an Object
we abstract irl all the time
baseball, soccer ball, basketball... they are all Ball
Baseball extends Ball
SoccerBall extends Ball
BasketBall extends Ball
left tartan
so they are all part of the same thing
deep ravine
equals(Obiect) expects an Object
left tartan
what does say for appliance
left tartan
alright
deep ravine
so you can still pass Appliance objects to it
uncut marsh
instead of equals(Appliance y)
deep ravine
anything that extends Object, you can pass to that method
uncut marsh
its equals(Object y)
left tartan
uncut marsh
you have to check if y is an Appliance, so you can use SRN
deep ravine
instanceof is the keyword here
left tartan
`instanceof` is the keyword here
instance? llike instance varible?
left tartan
deep ravine
yup
left tartan
oh its staying
deep ravine
look at examples of equals while you're at it
left tartan
y is an instance of appliance
deep ravine
easy info
uncut marsh
y is an instance of appliance
yes
deep ravine
"java equals example"
left tartan
wait object has to have a variable too?
deep ravine
what do you mean?
deep ravine
yup, you need to introduce a new variable
left tartan
deep ravine
and cast the value
if using newer versions, you could define the variable within the if condition
left tartan
wait so in the parenthesis
deep ravine
if(y instanceof Appliance app) {
// can use app
}```object needs a letter
left tartan
i'm not sure which version
left tartan
right here u said casting right
so for me
(appliance) o
Appliance y = (Appliance) O;
deep ravine
you dont have an o in your code
left tartan
you dont have an `o` in your code
i just wrote it in
deep ravine
oh, so you changed Object y to Object o
left tartan
it was object y
deep ravine
and now theres an error on y
you should be checking if the parameter is an instanceof Application
left tartan
yea it says the letters tharts the instance of
deep ravine
the parameter is Object o
deep ravine
yea it says the letters tharts the instance of
not sure what you mean
left tartan
left tartan
not sure what you mean
i mixed up the letters
i didn't notice until u pointed them out
deep ravine
you should use more descriptive names for your variables
instead of y, could use obj or something similar
other, since it represents another value (something you are comparing with, checking if it equals)
instead of Appliance o, should do Appliance appliance or even Appliance app
left tartan
the letter feels simple
deep ravine
its too simple
so simple, you got confused
the more descriptive you are, the easier things will be to navigate
if(i <= o && j > k)```no one wants to see that
when a bug appears, no one wants to be looking through code like that
left tartan
could u explain why srn would still be red
deep ravine
look at the variable you're using
deep ravine
which variable?
left tartan
over here
deep ravine
thats the problem, dont just blindly follow..
which variable are you calling SRN from?
left tartan
y
deep ravine
what is the type of y?
left tartan
Appliance
left tartan
oh of object
deep ravine
yup
so right there, its flagging it
Object has no SRN member
"but i did instanceof and all that jazz"
ya did it wrong
so your IDE is correct
left tartan
```java
if(y instanceof Appliance app) {
// can use app
}```
u have app here
deep ravine
you arent gonna get it from Object y
thats the whole point of Appliance o
you check to see if the object is an Appliance. if it is, introduce a new variable
assign that new variable, give it the y, but turned into the proper type (casting)
Appliance o = (Appliance) y;```y is seen as Object
thats why you need a new variable, which has the type Appliance
i got the feeling you either missed out on a lot of lessons, or your professor should be fired
left tartan
no i go everyday
deep ravine
do you pay attention everyday? 😂
left tartan
yeah of course
we haven't ever talked about this though
but i'm trying to understand
back to this
@Override
public boolean equals(Object y) {
if(y instanceof Appliance) {
Appliance o = (Appliance) y;
}
return this.SRN.equals(y.SRN);
}```the problem is
object y right
thats what u said
but this part ```java
Appliance o = (Appliance) y;
are u saying it should be the other way around
I have class in a bit. i'll be back
deep ravine
but this part ```java
Appliance o = (Appliance) y;
```
no, im saying y does not have access to SRN, because the datatype is Object
you passed the value to a variable with a different datatype, Application o
that's the Application o = y; part
left tartan
Ok i'm back
I'll be honest, I see what ur telling me
But i don't know what to do about it
deep ravine
But i don't know what to do about it
think about the code in front of you.. look at what you have available
you have Appliance o
you arent doing anything with it
left tartan
okay lemme put out what i have and think again
@Override
public boolean equals(Object obj)
) {
if(obj instanceof Appliance) {
Appliance x = (Appliance) obj;
return this.SRN.equals(other.SRN);
}```i name it obj
for now
deep ravine
```java
@Override
public boolean equals(Object obj)
) {
if(obj inst...
where did other come from?
left tartan
i just wrote that as a placeholder
deep ravine
no need for a placeholder
use the Appliance variable
y didnt have access to SRN, because of the variable type
left tartan
so other would be the same way then
deep ravine
what do you mean?
left tartan
i thought u were saying y didn't have access
so why would putting other change anything
deep ravine
putting other makes no sense, thats why i asked about it
deep ravine
```java
@Override
public boolean equals(Object obj)
) {
if(obj inst...
this makes no sense. take a closer look
you have a variable Object obj which you never use
you have obi instanceof
other isnt a variable. you got Application o variable which you never use
sometimes you get so focused on solving the issue, you dont realize whats in front of you
i saw you edited to fix
looks a lot better. but other, you dont know what to put
left tartan
@Override
public boolean equals(Object obj){
if(obj instanceof Appliance) {
Appliance x = (Appliance) obj;
return this.SRN.equals(x.SRN);
}```yeah i just
deep ravine
you cleaned up 90% of the "what?" right there
deep ravine
there you go
left tartan
no nvm
left tartan
wdym yes
deep ravine
you saw it
left tartan
wait ebfore
deep ravine
you arent done, but x.SRN was basically the golden ticket
left tartan
the if maybe
deep ravine
then you didnt know what to put, so you put other
deep ravine
this
deep ravine
left tartan
@Override
public boolean equals(Object obj){
if(obj instanceof Appliance){
return true;}
else {
return false;
}
Appliance x = (Appliance) obj;
return this.SRN.equals(x.SRN);
}```so my x.srn
deep ravine
yes
obj can accept any value, because of the datatype Object
we can do appliance.equals(new Dog()); if we wanted
thats why you have the if
you wanna make sure the value isnt a dog, or a bicycle, etc.. you are checking if the value is an Appliance
does that part make sense?
left tartan
but how do u check that it is
deep ravine
you check if obj is an instanceof Appliance
left tartan
i mean other than the if statement i guess since that can't be it
deep ravine
which you are doing
left tartan
i gues thats not enough
deep ravine
hm? enough for what?
thats enough to check if obj is referencing an Appliance object
left tartan
and if it is
left tartan
thats enough to check if `obj` is referencing an `Appliance` object
yeah but if i'm doing that
why is ther still a bug
what am i missing
deep ravine
because you dont understand methods properly
you are missing a ton, my friend..
but in this case, its 1 thing
you need to return
deep ravine
yup
left tartan
ye i think i was thinking the if had a statement after the condition so it was fine
left tartan
you need to `return`
@Override
public boolean equals(Object obj){
if(obj instanceof Appliance)
return true;
Appliance x = (Appliance) obj;
return this.SRN.equals(x.SRN);
}```soooooo far off
look at what your code says
if(obj instanceof Appliance)
return true;```what do you think thats gonna do?
this is why im worried about the whole "understand what the code is doing"
you were 2 inches away from the solution. but 1 change put you 5 miles away
left tartan
if obj is an instance of appliance, its gonna return true
left tartan
well use it
left tartan
use it to compare to another serieal number
deep ravine
so right there, thats your goal
what if the object is not an appliance?
what then?
left tartan
return false?
deep ravine
so you seem to understand what you need to do
now look at your code. does it reflect that?
left tartan
if its not an appliance, what else can u do, u need to only use appliances
deep ravine
exactly
left tartan
so i need a return false in there as well
deep ravine
if(is appliance) {
} else {
return false;
}```right?
youd use instanceof of course, is isnt Java syntax
left tartan
hold on
deep ravine
but thats the idea, yeah?
left tartan
ye
i was about to ask
@Override
public boolean equals(Object obj){
if(obj instanceof Appliance){
return true;
}
else{
return false;
}
}```please tell me thats at least closer
deep ravine
```java
@Override
public boolean equals(Object obj){
if(obj instanceof A...
kind of. for now, remove the Appliance x = ... and the return this.SRN at the bottom
deep ravine
that will at least bring you to a point where the code will run (no squiggles) AND you understand what is going on
we can build on this
if its not an appliance, return false, easy
if it is, what do we do?
do we return true immediately?
deep ravine
what about the serial number?
deep ravine
yup. if its an appliance, compare
left tartan
it only is saying that this varible is an applaince right nowright
left tartan
so the other if was for
take this applaince
and comapre it
or uh eqauls
to another appliance
deep ravine
you need to check if the serials are equal, yeah
left tartan
yeah
deep ravine
if(serials are equal) {
return true;
} else {
return false;
}```