//: arrays/ArrayOptions.java // Initialization & re-assignment of arrays. import java.util.*; import static net.mindview.util.Print.*; public class ArrayOptions { public static void main(String[] args) { // Arrays of objects: BerylliumSphere[] a; // Local uninitialized variable BerylliumSphere[] b = new BerylliumSphere[5]; // The references inside the array are // automatically initialized to null: print("b: " + Arrays.toString(b)); BerylliumSphere[] c = new BerylliumSphere[4]; for(int i = 0; i < c.length; i++) if(c[i] == null) // Can test for null reference c[i] = new BerylliumSphere(); // Aggregate initialization: BerylliumSphere[] d = { new BerylliumSphere(), new BerylliumSphere(), new BerylliumSphere() }; // Dynamic aggregate initialization: a = new BerylliumSphere[]{ new BerylliumSphere(), new BerylliumSphere(), }; // (Trailing comma is optional in both cases) print("a.length = " + a.length); print("b.length = " + b.length); print("c.length = " + c.length); print("d.length = " + d.length); a = d; print("a.length = " + a.length); // Arrays of primitives: int[] e; // Null reference int[] f = new int[5]; // The primitives inside the array are // automatically initialized to zero: print("f: " + Arrays.toString(f)); 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: //!print("e.length = " + e.length); print("f.length = " + f.length); print("g.length = " + g.length); print("h.length = " + h.length); e = h; print("e.length = " + e.length); e = new int[]{ 1, 2 }; print("e.length = " + e.length); } } /* Output: b: [null, null, null, null, null] a.length = 2 b.length = 5 c.length = 4 d.length = 3 a.length = 3 f: [0, 0, 0, 0, 0] f.length = 5 g.length = 4 h.length = 3 e.length = 3 e.length = 2 *///:~