| Java Threads Interview Questions And Answers |
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| 1 |
what are the two types of multitasking? |
| Ans: |
a. Process-based.
b. Thread-based. |
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| 2 |
what is a Thread? |
| Ans: |
A thread is a single sequential flow of control within a program. |
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| 3 |
what are the two ways to create a new thread? |
| Ans: |
A.Extend the Thread class and override the run () method.
B.Implement the Runnable interface and implement the run () method. |
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| 4 |
If you have ABC class that must subclass XYZ class, which option will you use to create a thread? |
| Ans: |
I will make ABC implement the Runnable interface to create a new thread, because ABC class will not be able to extend both XYZ class and Thread class. |
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| 5 |
which package contains Thread class and Runnable Interface? |
| Ans: |
java. Lang package |
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| 6 |
what is the signature of the run () mehod in the Thread class? |
| Ans: |
public void run () |
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| 7 |
shich methods calls the run () method? |
| Ans: |
start () method. |
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| 8 |
which interface does the Thread class implement? |
| Ans: |
Runnable interface |
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| 9 |
what are the states of a Thread? |
| Ans: |
Ready, Running, Waiting and Dead. |
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| 10 |
where does the support for threading lie? |
| Ans: |
The thread support lies in java.lang.Thread, java.lang.Object and JVM. |
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| 11 |
In which class would you find the methods sleep () and yield ()? |
| Ans: |
Thread class |
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| 12 |
In which class would you find the methods notify (), notify All () and wait ()? |
| Ans: |
Object class |
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| 13 |
what will notify () method do? |
| Ans: |
notify() method moves a thread out of the waiting pool to ready state, but there is no guaranty which thread will be moved out of the pool. |
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| 14 |
Can you notify a particular thread? |
| Ans: |
No. |
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| 15 |
what is the difference between sleep () and yield ()? |
| Ans: |
When a Thread calls the sleep () method, it will return to its waiting state. When a Thread calls the yield () method, it returns to the ready state. |
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| 16 |
what is a Daemon Thread? |
| Ans: |
Daemon is a low priority thread which runs in the backgrouund. |
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| 17 |
How to make a normal thread as daemon thread? |
| Ans: |
We should call set Daemon (true) method on the thread object to make a thread as daemon thread. |
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| 18 |
what is the difference between normal thread and daemon thread? |
| Ans: |
Normal threads do mainstream activity, whereas daemon threads are used low priority work. Hence daemon threads are also stopped when there are no normal threads. |
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| 19 |
Give one good example of a daemon thread? |
| Ans: |
Garbage Collector is a low priority daemon thread. |
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| 20 |
what does the start () method of Thread do? |
| Ans: |
The thread's start () method puts the thread in ready state and makes the thread eligible to run. Start () method automatically calls the run () method. |
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