Overview
- Defining Thread
- Creating & Starting a Thread
- Thread States
- Preventing Thread Execution
- Thread Sleeping
- Thread priorities
- Synchronization
- Thread Interaction
In Java, threads are a fundamental part of the language and its libraries, allowing you to create and manage concurrent execution of tasks within a program. Java provides a built-in Thread class and a java.util.concurrent package for more advanced thread management.
Defining Threads
- Extend class java.lang.Thread & Override run method E.g.:-
class ThreadDemo extends Thread {
public void run() {
//your code
}
}
- Implement java.lang.Runnable interface E.g:-
class ThreadDemo implements Runnable {
public void run() {
//your code
}
}
Creating & Starting Threads
- When the class extends java.lang.Thread class E.g.:-
ThreadDemo t = new ThreadDemo();
t.start();
- When the class implements java.lang.Runnable interface E.g.
ThreadDemo obj = new ThreadDemo();
Thread t = new Thread(obj);
t.start();
Thread States
- New:-This is the state the thread is in after the Thread instance has been created, but the start() method has not been invoked on the thread.
- Runnable:-This is the state a thread is in when it’s eligible to run, but the scheduler has not selected it to be the running thread. A thread first enters the runnable state when the start() method is invoked.
- Running:-When the scheduler chooses the thread to be running as the current process.
Thread States (Continued)
- Waiting/Blocked/Sleeping:- This is the state where the thread is still alive but not eligible to run.
- Dead:- This is the state when the run method of the Thread has completed its execution and it no longer remains a separate thread of execution.
Preventing Thread Execution
- Thread is sleeping.
- Thread is waiting.
- Thread is blocked for acquiring an object’s lock.
Thread sleeping
- Makes the running thread go into the sleep state for some specified time
- Makes the current running thread give up the processor temporarily, but keeps the thread in runnable state.
- Makes the current thread wait for the end of execution of the thread it is joined to.
Thread Priorities
- Thread.MIN_PRIORITY (1)
- Thread.NORM_PRIORITY (5) (1)
- Thread.MAX_PRIORITY (10) (1)
