Core Java - Interview Questions and Answers for 'Ocjp' | Search Interview Question

Core Java - Interview Questions and Answers for 'Ocjp' - 9 question(s) found - Order By Newest

Q1. Which of the following are valid declarations

1. void method(int... x){};
2. void method(int.. x){};
3. void method(int.. .x){};
4. void method(int ...x){};
5. void method(int... x){};
6. void method(int ... x){};
7. void method(int x, int... y){};
8. void method(int... x, int y){};
9. void method(int... x,int... y){};

Core Java

Ans. 1st is a valid and standard declaration.

2nd results in compilation error as only 2 dots are there.

3rd results in compilation error as three dots are not consecutive and broken.

4 through 6 may not be standard and ideal way of declarations but they are valid and will compile and work fine.

7 is valid declaration.

8 and 9 will result in compilation error as var args can only be provided to last argument.

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Q2. Can we overload method as following ?

void method(int... x){};
void method(int[] x){};

Core Java

Ans. No. Because java internally treats var args as arrays and hence both method declarations will generate the same byte code and hence would result in ambiguity while determining call binding.

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Q3. Which of the following syntax is correct ?import static java.lang.System.*;or static import java.lang.System.*;

Core Java

Ans. import static java.lang.System.*;

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Q4. Which of the following code is correct ?

a.

FileWriter fileWriter = new FileWriter("../file.txt");
File file = new File(fileWriter );
BufferedWriter bufferedOutputWriter = new BufferedWriter(fileWriter);

b.

BufferedWriter bufferedOutputWriter = new BufferedWriter("../file.txt");
File file = new File(bufferedOutputWriter );
FileWriter fileWriter = new FileWriter(file);

c.

File file = new File("../file.txt");
FileWriter fileWriter = new FileWriter(file);
BufferedWriter bufferedOutputWriter = new BufferedWriter(fileWriter);

d.

File file = new File("../file.txt");
BufferedWriter bufferedOutputWriter = new BufferedWriter(file);
FileWriter fileWriter = new FileWriter(bufferedOutputWriter );

Core Java

Ans. c.

File file = new File("../file.txt");
FileWriter fileWriter = new FileWriter(file);
BufferedWriter bufferedOutputWriter = new BufferedWriter(fileWriter);

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Q5. Which exceptions should be handled with the following code ?

FileOutputStream fileOutputStream = new FileOutputStream(new File("newFile.txt"));

Ans. FileNotFoundException

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Q6. What will the following code print ?

java.util.Calendar c = java.util.Calendar.getInstance();
c.add(Calendar.MONTH, 5);
System.out.println(c.getTime());

Core Java

Ans. Date and Time after 5 months from now.

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Q7. What will the following code print ?

public static void main(String[] args){
Integer i1 = new Integer("1");
Integer i2 = new Integer("2");
Integer i3 = Integer.valueOf("3");
int i4 = i1 + i2 + i3;
System.out.println(i4);
}

Core Java

Ans. 6

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Q8. Why following method declarations are not valid ?

void method(int... x, int y){};
void method(int... x,int... y){};

Core Java

Ans. Because var args are not only allowed with the last argument in the method declaration.

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Q9. Which method will get called if we call it as method(1)

void method(int x ){};
void method(int... x){};

Core Java

Ans. Though the call an be bind to either of these but in this case, 1st method will get priority and hence will be called.

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