Java Arrays Declaration and Initialization Practice

Array Declaration and Initialization

• To create an array with 20 double elements, use double[] array = new double[20];
• The correct syntax for declaring and initializing an array is int[] array = {4, 3, 5, 2, 0};

Array Element Access

• The value of array in the declaration int[] array = {4, 3, 5, 2, 0}; is 4 at index 0, 3 at index 1, 5 at index 2, 2 at index 3, and 0 at index 4.
• Accessing an array element out of bounds causes a runtime error.

Looping and Array Initialization

• The code segment int[] values = new int[10]; for (int k = 0; k < values.length; k++) { values[k] = k * 2; } initializes an array with values 0, 2, 4, ..., 18.
• The missing statement in the code fragment int[] numbers = new int[100]; for (int k = 0; k < numbers.length; k++) { ________________________ } is numbers[k] = k + 1;

Array Variables and Enhanced for Loop

• The code segment int[] values = { 1, 3, 1, 3, 1 }; int[] numbers = values; for (int k = 0; k < values.length; k++) { values[k] = k * 2; } outputs 0 2 4 6 8 for values and 0 2 4 6 8 for numbers.
• The enhanced for loop int[] values = { 1, 3, 5, 3, 7 }; int count = 0; for (int number : values) { if (number > 4) { count++; } } outputs 2 for count.
• The most appropriate statement for the body of an enhanced for loop is System.out.println(number);

Array Algorithm

• The purpose of the code segment int count = 0; for (int k = 0; k < values.length; k++) { if (values[k] % 2 == 0) { System.out.println(number); } } is to count the number of even values in the array values.