What if we call run () method directly instead start () method in Java?

Why we call start () method which in turns calls Run method Why not we directly call run method?

Calling start () will start a new Thread and calling run() method does not start a new Thread. If you call start() method on Thread, Java Virtual Machine will call run() method and two threads will run concurrently now – Current Thread and Other Thread or Runnable implementation.

What is difference between calling start () and run () method of thread?

start method of thread class is implemented as when it is called a new Thread is created and code inside run() method is executed in that new Thread. While if run method is executed directly than no new Thread is created and code inside run() will execute on current Thread and no multi-threading will take place.

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What will happen when we call start () method?

What happens when a function is called?

  1. The arguments are evaluated.
  2. A new stack frame is pushed into the call stack.
  3. Parameters are initialized.
  4. Method body is executed.
  5. Value is retured and current stack frame is popped from the call stack.

What is difference between start () and run () in Java?

So what is the difference between the start and run method? Main difference is that when program calls start() method a new Thread is created and code inside run() method is executed in new Thread while if you call run() method directly no new Thread is created and code inside run() will execute on current Thread.

Can we directly call run method?

No, you can not directly call run method to start a thread. … If you call run method directly , it won’t create a new thread and it will be in same stack as main.

What is run () and start () method?


start() run()
Creates a new thread and the run() method is executed on the newly created thread. No new thread is created and the run() method is executed on the calling thread itself.
Can’t be invoked more than one time otherwise throws java.lang.IllegalStateException Multiple invocation is possible

What is start () method?

The start() method of thread class is used to begin the execution of thread. The result of this method is two threads that are running concurrently: the current thread (which returns from the call to the start method) and the other thread (which executes its run method).

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What does run () Do Java?

The run() method of thread class is called if the thread was constructed using a separate Runnable object otherwise this method does nothing and returns. When the run() method calls, the code specified in the run() method is executed. You can call the run() method multiple times.

How does run () method is invoked?

When a Thread object’s run() method is invoked directly, the statements in the run() method are executed by the current thread rather than by the newly created thread.

Can we call start method twice?

No. After starting a thread, it can never be started again. If you does so, an IllegalThreadStateException is thrown. In such case, thread will run once but for second time, it will throw exception.

Can we call run method twice?

2 Answers. The run method is called twice. One call is by calling start() in the MyRunnable constructor; this is executed in the separate thread.

What is the purpose of join method?

Thread class provides the join() method which allows one thread to wait until another thread completes its execution. If t is a Thread object whose thread is currently executing, then t. join() will make sure that t is terminated before the next instruction is executed by the program.

What does it mean if a method is final?

You use the final keyword in a method declaration to indicate that the method cannot be overridden by subclasses. The Object class does this—a number of its methods are final .

What is difference between sleep and wait in Java?

It tells the calling thread (a.k.a Current Thread) to wait until another thread invoke’s the notify() or notifyAll() method for this object, The thread waits until it reobtains the ownership of the monitor and Resume’s Execution.

Difference between wait and sleep in Java.

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Wait() Sleep()
Wait() is not a static method. Sleep() is a static method.

What is deadlock in Java?

Deadlock describes a situation where two or more threads are blocked forever, waiting for each other. … A Java multithreaded program may suffer from the deadlock condition because the synchronized keyword causes the executing thread to block while waiting for the lock, or monitor, associated with the specified object.