Output of Java Programs | Set 42 (Arrays)

Prerequisite : Java Arrays

Question 1. What is the output of this question?

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class Test1 {
public
    static void main(String[] args)
    {
        int arr[] = new int[5];
        int arr2[] = new int['a'];
        byte bt = 10;
        int arr3[] = new int[bt];
        System.out.println(arr.length);
        System.out.println(arr2.length);
        System.out.println(arr3.length);
    }
}

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Option
A) Error
B) Runtime Exception
C) 5
97
10
D) 5
65
10

Output: C

Explanation : To specify array size allowed data type are – byte, short, int, char and all of these are valid data types here.

Question 2. What is the output of this question?

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class Test2 {
public
    static void main(String[] args)
    {
        int a[] = new int[5]; // line 1
        int[] a11 = new int[]; // line 2
    }
}

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Option
A) Error
B) Exception
C) Run successfully
D) None

Output: A

Explanation : One Dimension array have size declaration as compulsory feature.

Error : array dimension missing
int []a11 = new int[]; // line 2

Question 3. Which of the following declarations are invalid?

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class Test3 {
public
    static void main(String[] args)
    {
        int[][] arr1 = new int[2][3]; // Line 1
        int[][] arr2 = new int[2][]; // line 2
        int[][] arr3 = new int[][]; // line 3
        int[][] arr4 = new int[][2]; // line 4
    }
}

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Option
A) All
B) line 1, 3, 4
C) line 3, 4
D) line 2, 3, 4

Output: C

Explanation : First two declarations are allowed and so no error. line 3 and 4 have zero and last dimension respectively.
error: array dimension missing

int [][]arr3=new int[][];//line 3
                          ^
error: ']' expected
  int [][]arr4=new int[][2];//line 4
                         ^
error: ';' expected
  int [][]arr4=new int[][2];//line 4

Question 4. Which of the following lines give error?

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class Test4 {
public
    static void main(String[] args)
    {
        int[][][] arr1 = new int[1][2][3]; // Line 1
        int[][][] arr2 = new int[1][2][]; // Line 2
        int[][][] arr3 = new int[2][][]; // Line 3
        int[][][] arr4 = new int[][][]; // Line 4
        int[][][] arr5 = new int[][2][3]; // Line 5
        int[][][] arr6 = new int[][][3]; // Line 6
        int[][][] arr7 = new int[][2][]; // Line 7
    }
}

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Option
A) line 4, 5, 6, 7
B) All
C) No Error
D) line 4, 7

Output: A

Explanation : In three dimensional array have first two dimension declaration is compulsory other wise we will get compile time error:illegal startup expression.

Question 5. What is the output of this question?

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class Test5 {
public
    static void main(String[] args)
    {
        int arr[] = new int[5];
        System.out.println(arr);
        System.out.println(arr[0]);
    }
}

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Option
A) 0
0
B)[I@6bc7c054
0
C) 0 0 0 0 0
0
D) none

Output: B

Explanation : arr : It is giving the base address of array
arr[0] : It is giving value of array element at 0th location.

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