Java Arrays

An array is an object that stores a fixed number of values of the same type in contiguous memory. Indexing starts at 0.

Declaring and Initialising

Java

int[] a = new int[5];          // 5 elements, all 0
int[] b = {10, 20, 30, 40};    // literal
System.out.println(b.length);  // 4

Example: Largest Element

Java

int[] marks = {45, 78, 91, 66, 83};
int max = marks[0];
for (int m : marks) {
    if (m > max) max = m;
}
System.out.println("Largest: " + max);

Largest: 91

2D Array (Matrix)

Java

int[][] m = { {1, 2, 3}, {4, 5, 6} };
for (int i = 0; i < m.length; i++) {
    for (int j = 0; j < m[i].length; j++) {
        System.out.print(m[i][j] + " ");
    }
    System.out.println();
}

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Watch outAccessing a[a.length] throws ArrayIndexOutOfBoundsException.

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