Every Java thread has a priority value. The scheduler uses it to decide which thread runs next.

Definition List

• Thread Priority: A value that influences thread scheduling order.
• Thread Scheduler: JVM component that decides which thread executes.
• CPU Time: Processor time allocated to a thread.
• Yield: Temporarily pauses the current thread for others to execute.

Priority Range in Java

• MIN_PRIORITY — 1
• NORM_PRIORITY — 5 (default)
• MAX_PRIORITY — 10

Thread Priority Constants

public static int MIN_PRIORITY   // 1
public static int NORM_PRIORITY  // 5
public static int MAX_PRIORITY   // 10

Setting Thread Priority

// Syntax
thread.setPriority(priorityValue);

// Example
thread.setPriority(Thread.MAX_PRIORITY);

Getting Thread Priority

// Syntax
thread.getPriority();

// Example
System.out.println(thread.getPriority());

Example 01: Thread Priority in Java

package com.java.Multi_threading;

class PriorityExample {

    public static void main(String[] args) {

        Thread thread1 = new Thread(new MyRunnable(), "Thread 1");
        Thread thread2 = new Thread(new MyRunnable(), "Thread 2");

        thread1.setPriority(Thread.MIN_PRIORITY);
        thread2.setPriority(Thread.MAX_PRIORITY);

        thread1.start();
        thread2.start();
    }
}

class MyRunnable implements Runnable {

    @Override
    public void run() {
        for (int i = 0; i < 5; i++) {
            System.out.println(Thread.currentThread().getName() + " - Count: " + i);
            Thread.yield();
        }
    }
}

Output

Thread 2 - Count: 0
Thread 2 - Count: 1
Thread 1 - Count: 0
Thread 2 - Count: 2
Thread 1 - Count: 1
...

Thread Priority Methods

• setPriority() — Assigns a priority to a thread.
• getPriority() — Returns the current thread priority.
• currentThread() — Returns a reference to the executing thread.
• getName() — Returns the name of the thread.

Understanding Thread.yield()

Thread.yield();

Suggests the current thread pause for others. The scheduler may ignore it.

Best Practices

• Use default priority for most applications.
• Avoid extreme MIN or MAX priority values.
• Don't rely solely on priority for thread control.
• Test scheduling behavior across different platforms.

FAQ

1. What is thread priority in Java?

A value between 1 and 10 that influences CPU time allocation.

2. What is the default thread priority?

Thread.NORM_PRIORITY — value of 5.

3. Does higher priority guarantee execution first?

No. Priority is a hint only. JVM and OS decide final order.