In Multithreading, both wait() and sleep() methods are used to make a thread to sleep. The main difference between both of them is, wait() puts a thread to sleep and forces it to move to suspended state, whereas, sleep puts a thread sleep for specified milliseconds.
| Sleep Method | Wait Method |
|---|---|
| It puts a thread to sleep for some time and makes that thread to automatically wake up after specified time ends | It forces a thread to sleep until notify() gets triggered |
| It doesn't force a thread to release its lock before completing its task | It forces a thread to release its lock before completing its task |
| It is not mandatory to define it within synchronised block | It is mandatory to define it within synchronised block |
| It halts a thread execution temporarily | It halts a thread execution permanently |
| It is invoked on thread | It is invoked on object |
| A thread awakes automatically or by interrupt() | A thread awakes by notify() and notifyAll() |
| It controls a thread's execution time | It controls multi-thread synchronization |
Wait method makes a thread sleep and forces it to move to suspended state.
It also causes a thread to release its acquired lock.So that, other threads can get turn in order to perform their respective jobs.
A wait method always pair with a notify method. Both together provides a way of interthread communication.
Program:
class WaitExample extends Thread
{
@Override
public void run() {
print();
}
synchronized void print()
{
System.out.println("THis is child ");
notify();
}
}
public class Main {
public static void main(String[] args) {
WaitExample thread = new WaitExample();
thread.start();
synchronized (thread)
{
System.out.println("I am in synchronised :");
try {
thread.wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println("I am in invoked :");
}Output:
Sleep method puts a thread to sleep too but for specified milliseconds.
It allows a thread to carry out its remaining task once provided time ends. Unlike wait(), it doesn’t order a thread to release its locks until it completes its task.
Program:
class ThreadExample extends Thread{
@Override
public void run() {
System.out.println("Child thread is about to sleep");
try {
sleep(3000);
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println("I am child Thread ");
}
}
public class Main {
public static void main(String[] args) {
ThreadExample thread1 = new ThreadExample();
thread1.start();
System.out.println("I am Main Thread ");
}
}
Output
Child thread is about to sleep
I am Main Thread
I am child Thread
This post was last modified on October 6, 2020