Arrays in Java

Java stores lists of values as arrays. An array names a contiguous group of related memory locations. Arrays in Java are objects and space for them must be allocated with the new operator.

double v[] = new double[10]; To refer to a particular element of an array, we specify the name of the array and a position number, indexed from zero. v[4] = 32.0; The length of an array v is determined by the expression v.length Every array in Java knows its own length.

The elements of an array can be allocated and initialized by an initializer list:

int nval[] = { 10, 30, 15, 5 }; Arrays are passed to methods by reference. double [] getArray() returns an array of doubles.
void passArray(double [] arg) receives an array of doubles.

Example

public class Arrays {
	public static void main( String args[] )
	{
		int in[] = MethodA();
		int inx[] = in;
		System.out.println("The two arrays are" + (inx==in?" ":" NOT ") + "equal");
		System.out.println("Array inx.toString() = " + inx.toString() );
		System.out.println("Array in.toString() = " + in.toString() );
		MethodB(in);
		in[3] = 44;
		System.out.println("Change in[3] to 44, inx[3] is " + inx[3]);
	}
	public static int [] MethodA()
	{
		int n[] = { 19, 3, 15, 7, 11, 9, 13, 5, 17, 1 };
		System.out.println("MethodA.n.toString() = " + n.toString() );
		return n;
	}
	public static void MethodB(int [] inp)
	{
		System.out.println("Input array has " + inp.length + " elements");
	}
}

Maintained by John Loomis, last updated 1 June 2000