Title here
Summary here
Our first example demonstrates the use of arrays in Java. In Java, an array is a fixed-size collection of elements of the same type.
public class Arrays {
public static void main(String[] args) {
// Here we create an array 'a' that will hold exactly 5 integers.
// By default, an array is initialized with zeros for numeric types.
int[] a = new int[5];
System.out.println("emp: " + java.util.Arrays.toString(a));
// We can set a value at an index using the array[index] = value syntax,
// and get a value with array[index].
a[4] = 100;
System.out.println("set: " + java.util.Arrays.toString(a));
System.out.println("get: " + a[4]);
// The length property returns the length of an array.
System.out.println("len: " + a.length);
// Use this syntax to declare and initialize an array in one line.
int[] b = {1, 2, 3, 4, 5};
System.out.println("dcl: " + java.util.Arrays.toString(b));
// In Java, we can't use the ... syntax to let the compiler count elements.
// We need to explicitly specify the size or provide all elements.
// If you want to create an array with specific indices set,
// you'll need to do it manually in Java.
int[] c = new int[5];
c[0] = 100;
c[3] = 400;
c[4] = 500;
System.out.println("idx: " + java.util.Arrays.toString(c));
// Array types are one-dimensional, but you can create multi-dimensional
// arrays by creating arrays of arrays.
int[][] twoD = new int[2][3];
for (int i = 0; i < 2; i++) {
for (int j = 0; j < 3; j++) {
twoD[i][j] = i + j;
}
}
System.out.println("2d: " + java.util.Arrays.deepToString(twoD));
// You can create and initialize multi-dimensional arrays at once too.
twoD = new int[][] {
{1, 2, 3},
{4, 5, 6}
};
System.out.println("2d: " + java.util.Arrays.deepToString(twoD));
}
}
Note that arrays in Java are printed using Arrays.toString()
for one-dimensional arrays and Arrays.deepToString()
for multi-dimensional arrays.
To run this program, save it as Arrays.java
, compile it with javac Arrays.java
, and then run it with java Arrays
. The output will be:
emp: [0, 0, 0, 0, 0]
set: [0, 0, 0, 0, 100]
get: 100
len: 5
dcl: [1, 2, 3, 4, 5]
idx: [100, 0, 0, 400, 500]
2d: [[0, 1, 2], [1, 2, 3]]
2d: [[1, 2, 3], [4, 5, 6]]
Java arrays are similar to those in many other languages, providing a way to store multiple elements of the same type in a contiguous block of memory. They have a fixed size once created, and their elements can be accessed using zero-based indexing.