Need help, Monitors as synchronization , SharedBuffer as shared resource for communication

[barren bridge]

I don't know how to make multiple writer/modifiers threads to run concurrently.
Heres the requirement:
Multiple Writer threads should perform the action of writing, with each thread picking up a
string from the source. The source is a list of strings loaded from a file and each thread
should store its string in the shared buffer. Multiple Modifier threads should each collect a
string from the shared buffer, modify its content, and save it back in the same position of
the shared buffer. The Modifier thread that processes a string should mark it for the Reader
thread

[fickle oyster]

<@&987246399047479336> please have a look, thanks.

[fickle oyster]

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[barren bridge]

package textEditors.model;

import textEditors.main.Controller;

import java.util.concurrent.locks.Condition;

public class SharedBuffer {
    private int bufferSize;
    private Controller controller;
    private String[] buffer;
    private BufferStatus[] status;
    private int writePos;
    private int readPos;
    private int modifyPos;
    
    public SharedBuffer(int bufferSize, Controller controller) {
        this.bufferSize = bufferSize;
        this.controller = controller;
        buffer = new String[bufferSize];
        status = new BufferStatus[bufferSize];
        writePos = 0;
        readPos = 0;
        modifyPos = 0;

        for (int i = 0; i < bufferSize; i++) {
            buffer[i] = "";
            status[i] = BufferStatus.Empty;
        }
    }

    public synchronized void writeData(String line, String threadName) {
        while ( status[writePos] != BufferStatus.Empty) {
            try {
                wait();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }


        buffer[writePos] = line;
        status[writePos] = BufferStatus.New;
        System.out.println(threadName + " - has written \"" + line + "\", position " + writePos);
        String logEntry = threadName + " - has written \"" + line + "\", position " + writePos;
        controller.logbookStatus(logEntry);
        writePos = (writePos + 1) % bufferSize;
        notifyAll();
    }
    
    public synchronized void modifyData(String find, String replace, String threadName) {
        while (status[modifyPos] != BufferStatus.New) {
            try {
                wait();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        if (buffer[modifyPos].contains(find)) {
            buffer[modifyPos] = buffer[modifyPos].replace(find, replace);
            System.out.println(threadName + " - has modified " + find + " to " + replace + " at position " + modifyPos);
            String logEntry = threadName + " - has modified " + find + " to " + replace + " at position " + modifyPos;
            controller.logbookStatus(logEntry);
        }
        status[modifyPos] = BufferStatus.Checked;
        modifyPos = (modifyPos + 1) % bufferSize;
        notifyAll();
    }

    public synchronized String readData(String threadName) {
        String line = "";

        while (status[readPos] != BufferStatus.Checked) {
            try {
                wait();

            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        line = buffer[readPos];
        status[readPos] = BufferStatus.Empty;
        System.out.println(threadName + " - has read " + line + " position " + readPos);
        String logEntry = threadName + " - has read, position " + readPos;
        readPos = (readPos + 1) % bufferSize;

        notifyAll();
        return line;
    }

    public enum BufferStatus {
        Empty,
        Checked,
        New
    }
}

[fickle oyster]

Detected code, here are some useful tools:

Formatted code

package textEditors.model;

import textEditors.main.Controller;
import java.util.concurrent.locks.Condition;

public class SharedBuffer {
  private int bufferSize;
  private Controller controller;
  private String[] buffer;
  private BufferStatus[] status;
  private int writePos;
  private int readPos;
  private int modifyPos;
  public SharedBuffer(int bufferSize, Controller controller) {
    this .bufferSize = bufferSize;
    this .controller = controller;
    buffer = new String[bufferSize] ;
    status = new BufferStatus[bufferSize] ;
    writePos = 0;
    readPos = 0;
    modifyPos = 0;
    for (int i = 0; i < bufferSize; i++) {
      buffer[i]  = "";
      status[i]  = BufferStatus.Empty;
    }
  }
  public synchronized void writeData(String line, String threadName) {
    while (status[writePos]  != BufferStatus.Empty) {
      try {
        wait();
      } catch (InterruptedException e) {
        e.printStackTrace();
      }
    }
    buffer[writePos]  = line;
    status[writePos]  = BufferStatus.New;
    System.out.println(threadName + " - has written \"" + line + "\", position " + writePos);
    String logEntry = threadName + " - has written \"" + line + "\", position " + writePos;
    controller.logbookStatus(logEntry);
    writePos = (writePos + 1) % bufferSize;
    notifyAll();
  }
  public synchronized void modifyData(String find, String replace, String threadName) {
    while (status[modifyPos]  != BufferStatus.New) {
      try {
        wait();
      } catch (InterruptedException e) {
        e.printStackTrace();
      }
    }
    if (buffer[modifyPos] .contains(find)) {
      buffer[modifyPos]  = buffer[modifyPos] .replace(find, replace);
      System.out.println(threadName + " - has modified " + find + " to " + replace + " at position " + modifyPos);
      String logEntry = threadName + " - has modified " + find + " to " + replace + " at position " + modifyPos;
      controller.logbookStatus(logEntry);
    }
    status[modifyPos]  = BufferStatus.Checked;
    modifyPos = (modifyPos + 1) % bufferSize;
    notifyAll();
  }
  public synchronized String readData(String threadName) {
    String line = "";
    while (status[readPos]  != BufferStatus.Checked) {
      try {
        wait();
      } catch (InterruptedException e) {
        e.printStackTrace();
      }
    }
    line = buffer[readPos] ;
    status[readPos]  = BufferStatus.Empty;
    System.out.println(threadName + " - has read " + line + " position " + readPos);
    String logEntry = threadName + " - has read, position " + readPos;
    readPos = (readPos + 1) % bufferSize;
    notifyAll();
    return line;
  }
  public enum BufferStatus {
    Empty, Checked, New}
}

[rotund bramble]

It is always horrible/a challenge to deal with basic sync-patterns; therefor Java provides a higher abstraction for such tasks. One of them is - for example - a ForkJoinPool in combination with RecursiveAction/Task. The jaadoc for RecursiveAction shows the basic usage

[foggy sparrow]

Java also have atomic classes like AtomicInt and AtomicReference, these are thread safe wrappers e.g. AtomicInt is a thread safe Integer, you could probably do that to start with and see how it performs

[barren bridge]

Ok i will check that out thanks for the response!