Arrays In Java! Programming Trivia Questions Quiz

1. Given the code fragment:

public class Test{
    public static void main(String[] args) {
        /* line 3*/
        array[0] = 10;
        array[1] = 20;
        System.out.print(array[0]+ ": "+array[1]);
    }
}

Which code fragment, when inserted at line 3, enables the code to print 10:20?

Int [] array = new int[2];

Int [] array;array = int[2];

Int array = new int[2];

Int array[2];

The correct answer is "int [] array = new int[2];". This code fragment declares an array named "array" of type int with a length of 2. This allows the subsequent lines of code to assign values to the elements of the array and print them out as 10:20.

Explanation

The correct answer is "int [] array = new int[2];". This code fragment declares an array named "array" of type int with a length of 2. This allows the subsequent lines of code to assign values to the elements of the array and print them out as 10:20.

2. Given the following code:

public static void main(String[] args) {
    String[] planets = {"Mercury", "Venus", "Earth", "Mars"};
    System.out.println(planets.length);
    System.out.println(planets[1].length());
}

What is the output?

421

45

54

35

44

47

The code initializes an array called "planets" with four elements: "Mercury", "Venus", "Earth", and "Mars". The first print statement outputs the length of the array, which is 4. The second print statement accesses the element at index 1 of the array (which is "Venus") and outputs its length, which is 5. Therefore, the output is "4 5".

Explanation

The code initializes an array called "planets" with four elements: "Mercury", "Venus", "Earth", and "Mars". The first print statement outputs the length of the array, which is 4. The second print statement accesses the element at index 1 of the array (which is "Venus") and outputs its length, which is 5. Therefore, the output is "4 5".

3. The following grid shows the state of a 2D array:

This grid is created with the following code:

char[][] grid = new char[3][3];
grid[1][1] = 'x';
grid[0][0] = 'o';
grid[2][1] = 'x';
grid[0][1] = 'o';
grid[2][2] = 'x';
grid[1][2] = 'o';
//line n1

Which line of code, when inserted in place of //line n1, adds an x into the grid so that the grid contains three consecutive x's?

Grid[1][2] = 'x';

Grid[1][3] = 'x';

Grid[0][2] = 'x';

Grid[3][1] = 'x';

Grid[2][0] = 'x';

The line of code "grid[2][0] = 'x';" adds an 'x' into the grid so that the grid contains three consecutive x's. This is because it assigns the value 'x' to the element at index (2,0) in the 2D array, which is the bottom left corner of the grid.

Explanation

The line of code "grid[2][0] = 'x';" adds an 'x' into the grid so that the grid contains three consecutive x's. This is because it assigns the value 'x' to the element at index (2,0) in the 2D array, which is the bottom left corner of the grid.

4. Given the code fragment:

int nums1[] = new int[3];
int nums2[] = {1,2,3,4,5};
nums1 = nums2;
System.out.print("x: " + nums1[3]);

What is the result?

ArrayIndexOutOfBoundsException is thrown in runtime.

Compilation fails

X: 0

X: null

X: 4

X: 3

The code creates two arrays, nums1 and nums2. The size of nums1 is set to 3, but it is then reassigned to nums2. Therefore, nums1 now refers to the same array as nums2, which has a length of 5. When trying to access the element at index 3 of nums1, it will be accessing the element at index 3 of nums2, which is 4. So, the result will be "x: 4".

Explanation

The code creates two arrays, nums1 and nums2. The size of nums1 is set to 3, but it is then reassigned to nums2. Therefore, nums1 now refers to the same array as nums2, which has a length of 5. When trying to access the element at index 3 of nums1, it will be accessing the element at index 3 of nums2, which is 4. So, the result will be "x: 4".

5. Given the code snippet from a compiled Java source file:

public class MyFile{
    public static void main(String[] args) {
        String arg1 = args[1];
        String arg2 = args[2];
        String arg3 = args[3];
        System.out.println("Arg is "+ arg3);
    }
}

Which command-line arguments should you pass to the program to obtain the following result? Arg is 2

Java MyFile 0 1 2 3

Java MyFile 1 3 2 2

Java MyFile 1 2 2 3 4

Java MyFile 2 2 2

The correct answer is "java MyFile 1 3 2 2". This is because in the code snippet, the program is accessing the third command-line argument (args[3]) and assigning it to the variable arg3. So, to obtain the desired result "Arg is 2", we need to pass the value 2 as the third command-line argument.

Explanation

The correct answer is "java MyFile 1 3 2 2". This is because in the code snippet, the program is accessing the third command-line argument (args[3]) and assigning it to the variable arg3. So, to obtain the desired result "Arg is 2", we need to pass the value 2 as the third command-line argument.