Java ReentrantLock getOwner() Method

by Online Tutorials Library July 22, 2022

Java ReentrantLock getOwner() Method

The getOwner() method of ReentrantLock class returns the current owner thread of the lock. It returns null if not owned. When this method is called by a thread that is not the owner, the return value reflects a best-effort approximation of current lock status.

Syntax

Parameter

No parameter is passed.

Returns

the owner, or null if not owned

Throws

No Exception is thrown.

Example 1

  //import statement      import java.util.concurrent.locks.*;        class ReentrantLockgetOwnerExample1  {            public static void main (String args[]) throws InterruptedException {       ReentrantLockClass lock = new ReentrantLockClass();                   MyThread t1 = new MyThread(lock);                  t1.start();          t1.join();                }    }         class MyThread extends Thread {         ReentrantLockClass lock;            MyThread(ReentrantLockClass lock){          this.lock=lock;                }            public void run() {          if ( ! lock.tryLock()) {           System.out.println(this.getName() + “: lock1 owner: ” + lock.owner());          }           System.out.println(this.getName() + “: lock1 owner: ” + lock.owner());                }    }         class  ReentrantLockClass extends ReentrantLock {       String owner() {          Thread t =  this.getOwner();          if (t != null) {             return t.getName();          } else {             return “none”;          }       }    }  

Test it Now

Output:

Thread-0: lock1 owner: Thread-0

Example 2

  //import statements  import java.util.concurrent.locks.*;    class ReentrantLockgetOwnerExample2  {        public static void main(String args[]) throws InterruptedException {     ReentrantLockClass2 lock1 = new ReentrantLockClass2();     ReentrantLockClass2 lock2 = new ReentrantLockClass2();        MyThread1 thrd1 = new MyThread1(lock1, lock2);        MyThread1 thrd2 = new MyThread1(lock1, lock2);        thrd1.start();        thrd1.join();        thrd2.start();        thrd2.join();     }  }     class MyThread1 extends Thread {     ReentrantLockClass2 lock1;  ReentrantLockClass2 lock2;        MyThread1(ReentrantLockClass2 lock1, ReentrantLockClass2 lock2){        this.lock1=lock1;        this.lock2=lock2;     }        public void run() {        if ( ! lock1.tryLock()) {           lock2.tryLock();        }         System.out.println(this.getName() + “: lock1 owner: ” + lock1.owner());        System.out.println(this.getName() + “: lock2 owner: ” + lock2.owner());     }  }     class ReentrantLockClass2 extends ReentrantLock {     String owner() {        Thread t =  this.getOwner();        if (t != null) {           return t.getName();        } else {           return “none”;        }     }  }  

Test it Now

Output:

 Thread-0: lock1 owner: Thread-0  Thread-0: lock2 owner: none  Thread-1: lock1 owner: Thread-0  Thread-1: lock2 owner: Thread-1

Next TopicJava ReentrantLock

Java ReentrantLock getOwner() Method

Java ReentrantLock getOwner() Method

Syntax

Parameter

Returns

Throws

Example 1

Example 2

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