Web Article: Java Synchronized keyword Example

Example 1

package com.javacodegeeks.snippets.core.synchronizedexample;

import java.util.ArrayList;

public class SynchronizedMethodClass {

 private ArrayList < Integer > nums1;
 private String pos1;

    public SynchronizedMethodClass() {
     nums1 = new ArrayList < Integer >();
     nums1.add(0);
     pos1 = "0";
    }

 public ArrayList < Integer > getNums1() {
  return nums1;
 }

 public void setNums1(ArrayList < Integer > nums1) {
  this.nums1 = nums1;
 }

 public String getPos1() {
  return pos1;
 }

 public void setPos1(String pos1) {
  this.pos1 = pos1;
 }

 public synchronized void syncMethod(String threadName) {
     Integer number = nums1.get(nums1.size() - 1) + 1;
        pos1 = String.valueOf(number);
        nums1.add(number);
        System.out.println("Thread " + threadName + " : " 
+ nums1.get(nums1.size() - 1) + " - " + pos1);
    }
}

Example 2

package com.javacodegeeks.snippets.core.synchronizedexample;

import java.util.ArrayList;

public class SynchronizedBlockClass {

    private ArrayList < Integer > nums2;
    private String pos2;
    private int counter;
    
    public SynchronizedBlockClass() {
     nums2 = new ArrayList < Integer >();
     nums2.add(0);
     pos2 = "0";
    }
 
 public ArrayList < Integer > getNums2() {
  return nums2;
 }

 public void setNums2(ArrayList < Integer > nums2) {
  this.nums2 = nums2;
 }
 
 public String getPos2() {
  return pos2;
 }

 public void setPos2(String pos2) {
  this.pos2 = pos2;
 }

 public int getCounter() {
  return counter;
 }

 public void setCounter(int counter) {
  this.counter = counter;
 }

    public void syncBlock(String threadName) {
     counter++;
     System.out.println("Thread " + threadName + " - counter: " + counter);
        synchronized (this) {
         Integer number = nums2.get(nums2.size() - 1) + 1;
            pos2 = String.valueOf(number);
         nums2.add(number);
            System.out.println("Thread " + threadName + " Added to list: " 
              + nums2.get(nums2.size() - 1) + " - " + pos2);
           }
    }

}

Source: javacodegeeks