Various ways to determine if an entire string is a number in java / How to check if String does not contain number in java

There may be a scenario, if we want to determine whether a string is completely numeric or not, such as we want a user to input a number and our program should multiply it by 5 and return the result. User is a human. He may mistakenly input an alphanumeric string by mistake or to check the correctness of our program.
Off course, we would not like to show an exception trace to the user instead of the result. Better we check the input for its validity before processing. Below are various ways using which we may check that an input String is completely a number or not.
Check out: (more…)

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How to create a new Thread in Java / Various methods to create a Thread in Java

A little bit about thread

A thread is a piece of task which is to be executed in parallel to another task executed by an application.
Example, Consider a text editor which performs auto save operation after some particular length of text is typed into it.
Now there are two tasks, first showing the text typed into the editor and second, performing auto save.
Since the two tasks should be executed in parallel, they are performed in different threads. If both operations are done on the same thread, then while the thread is busy saving, it could not perform the typing process and it will show a lag till the save operation completes.

How to create Thread ?

There are a couple of ways of creating a thread. (more…)

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How to do a task repeatedly using threads in java / How to create a timer using ScheduledThreadPoolExecutor in java

Suppose we want to do a task after fixed time interval such as creating a beep sound after 5 seconds or checking the connection status after every 5 seconds. This may be easily accomplished using Executor framework in java.
There is a class called ScheduledThreadPoolExecutor which has the methods to perform such kind of scheduling. Let’s get down to code right away: (more…)

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