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|Interview Questions and Answers|
|Ans. We can use NumberUtils.isNumber which is a part of apache commons package.|
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|Like Discuss Correct / Improve  java   apache commons   numberutils   numberutils.isnumber|
|Difference between == and .equals() ?|
|Why is String immutable in Java ?|
| Explain the scenerios to choose between String , StringBuilder and StringBuffer ?|
What is the difference between String , StringBuilder and StringBuffer ?
|Why Char array is preferred over String for storing password?|
|What are different ways to create String Object? Explain.|
|What is a String Pool ?|
|How does making string as immutable helps with securing information ? How does String Pool pose a security threat ?|
|How is string object immutable if we can concat a string to it ?|
|What is StringJoiner ?|
| Which of the following is false about main method ?|
a. It should be declared public and static
b. it should have only 1 argument of type String array
c. We can override main method
d. We can overload main method