//: ArraySize.java // Initialization & re-assignment of arrays package c08;
class Weeble {} // A small mythical creature
public class ArraySize { public static void main(String[] args) { // Arrays of objects: Weeble[] a; // Null handle Weeble[] b = new Weeble[5]; // Null handles Weeble[] c = new Weeble[4]; for(int i = 0; i < c.length; i++) c[i] = new Weeble(); Weeble[] d = { new Weeble(), new Weeble(), new Weeble() }; // Compile error: variable a not initialized: //!System.out. System.out.println("b.length = " + b.length); // The handles inside the array are // automatically initialized to null: for(int i = 0; i < b.length; i++) System.out.println("b[" + i + "]=" + b[i]); System.out.println("c.length = " + c.length); System.out.println("d.length = " + d.length); a = d; System.out.println("a.length = " + a.length); // Java 1.1 initialization syntax: a = new Weeble[] { new Weeble(), new Weeble() }; System.out.println("a.length = " + a.length);
// Arrays of primitives: int[] e; // Null handle int[] f = new int[5]; int[] g = new int[4]; for(int i = 0; i < g.length; i++) g[i] = i*i; int[] h = { 11, 47, 93 }; // Compile error: variable e not initialized: //!System.out.println("e.length=" + e.length); System.out.println("f.length = " + f.length); // The primitives inside the array are // automatically initialized to zero: for(int i = 0; i < f.length; i++) System.out.println("f[" + i + "]=" + f[i]); System.out.println("g.length = " + g.length); System.out.println("h.length = " + h.length); e = h; System.out.println("e.length = " + e.length); // Java 1.1 initialization syntax: e = new int[] { 1, 2 }; System.out.println("e.length = " + e.length); } } ///:~ Here’s the output from the program:
