Java 8. Thread synchronization issue

Question

I have three objects: A, B, and C. I need such synchronization so that blocks synchronized with objects A and B can be executed in parallel, and when block synchronized with objects A or block synchronized with objects B is executed, block synchronized with objects C cannot be executed. And when block synchronized with objects C is executed, blocks synchronized with objects A and B cannot be executed. I tried to use object C as list, and objects A and B as objects stored in this list, but it did not work. Please tell me, is it possible to somehow configure such synchronization?

import java.util.ArrayList;
import java.util.List;

public class Threads {
    public List<Res> lst = new ArrayList();

    public void startThreads(){
        lst.add(new Res());
        lst.add(new Res());
        Thread t1 = new Thread(new work1());
        Thread t2 = new Thread(new work2());
        Thread t3 = new Thread(new work3());
        t1.start();
        t2.start();
        t3.start();
    }
    public class work1 implements Runnable {
        @Override
        public void run() {
            Method1();
        }
    }
    public class work2 implements Runnable {
        @Override
        public void run() {
             Method2();
        }
    }

    public class work3 implements Runnable {
        @Override
        public void run() {
            Method3();
        }
    }

    public void Method1(){
        synchronized (lst.get(0)/*obj A*/){ 
            //some work
        }
    }

    public void Method2(){
        synchronized (lst.get(1)/*obj B*/){
            //some work
        }
    }

    public void Method3(){
         synchronized (lst)/*obj C*/{
            //some work
        }
    }
}

Class Res:

public class Res {
    public int number = 0;
}

Class Main:

public class Main {
    public static void main(String[] args) throws InterruptedException {
        Threads t = new Threads();
        t.startThreads();
    }
}

Answer 1

In your case simplest (Not recommended) solution is to guard Block A and Block B with different monitor objects and guard Block C with the monitor obects of both A and B.

public void Method1(){
    synchronized (A){
        //some work
    }
}

public void Method2(){
    synchronized (B){
        //some work
    }
}

public void Method3(){
    synchronized (A){
        synchronized (B){
            //some work
        }
    }
}

Same can be done using Locks as well.

public void Method1(){
    lockA.lock();
    try{
        //some work
    } finally {
        lockA.unlock();
    }
}

public void Method2(){
    lockB.lock();
    try{
        //some work
    } finally {
        lockB.unlock();
    }
}

public void Method3(){
    lockA.lock();
    try{
        lockB.lock();
        try{
            //some work
        } finally {
            lockB.unlock();
        }
    } finally {
        lockA.unlock();
    }
}

Or you can use read/write lock as suggested by shmosel in the comments.

public void Method1(){
    readWriteLock.readLock().lock();
    try{
        //some work
    } finally {
        readWriteLock.readLock().unlock();
    }
}

public void Method2(){
    readWriteLock.readLock().lock();
    try{
        //some work
    } finally {
        readWriteLock.readLock().unlock();
    }
}

public void Method3(){
    readWriteLock.writeLock().lock();
    try{
        //some work
    } finally {
        readWriteLock.writeLock().unlock();
    }
}

You can also use CountDownLatch for the same purpose, though read/write lock is the easiest one.