Java Basic Easy Questions and Answers | Page - 26

Java Basic

Which is better in terms of performance for iterating an array?

1. for(int k=50; k>=0; k–)
1. for(int k=0; k<50; k++)
1. for(int k=50; k>0; k++)
1. for(int k=50; k<0; k++)
1. None of these

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Correct Option: A

reverse traversal of array take half number cycles as compared to forward traversal. The other for loops will go in infinite loop.

Which of the below is false about java coding?

1. class constants should be used when we want to share data between class methods
1. test case method names should be created as english sentences without spaces
1. variable names should be such that they avoid ambiguity
1. variable names should be short
1. None of these

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Correct Option: D

variable names like i, a, abc, etc should be avoided. They should be real world names which avoid ambiguity. Test case name should explain its significance.

Which of the below is true about java class structure?

1. The class should only contain those attribute and functionality which it should; hence keeping it short
1. The class attributes and methods should be public
1. The class should have thousands of lines of code
1. The class name should start with lowercase
1. None of these

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Correct Option: A

Class name should always start with upper case and contain those attribute and functionality which it should (Single Responsibility Principle); hence keeping it short. The attributes should be usually private with get and set methods.

Which of the following is a best practice to measure time taken by a process for execution?

1. System.getProcessingTime()
1. System.getCurrentTime()
1. System.nanoTime()
1. System.currentTimeMillis()
1. None of these

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Correct Option: C

System.nanoTime takes around 1/100000 th of a second whereas System.currentTimeMillis takes around 1/1000th of a second.

Which one of the following causes memory leak?

1. Release instances stored in static tables
1. Release database connection when querying is complete
1. Not using Finally block often
1. Use Finally block as much as possible
1. None of these

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Correct Option: C

Finally block is called in successful as well exception scenarios. Hence, all the connections are closed properly which avoids memory leak.