//: ArraySize.java ////////////////////////////////////////////////// // Copyright (c) Bruce Eckel, 1998 // Source code file from the book "Thinking in Java" // All rights reserved EXCEPT as allowed by the // following statements: You can freely use this file // for your own work (personal or commercial), // including modifications and distribution in // executable form only. Permission is granted to use // this file in classroom situations, including its // use in presentation materials, as long as the book // "Thinking in Java" is cited as the source. // Except in classroom situations, you cannot copy // and distribute this code; instead, the sole // distribution point is http://www.BruceEckel.com // (and official mirror sites) where it is // freely available. You cannot remove this // copyright and notice. You cannot distribute // modified versions of the source code in this // package. You cannot use this file in printed // media without the express permission of the // author. Bruce Eckel makes no representation about // the suitability of this software for any purpose. // It is provided "as is" without express or implied // warranty of any kind, including any implied // warranty of merchantability, fitness for a // particular purpose or non-infringement. The entire // risk as to the quality and performance of the // software is with you. Bruce Eckel and the // publisher shall not be liable for any damages // suffered by you or any third party as a result of // using or distributing software. In no event will // Bruce Eckel or the publisher be liable for any // lost revenue, profit, or data, or for direct, // indirect, special, consequential, incidental, or // punitive damages, however caused and regardless of // the theory of liability, arising out of the use of // or inability to use software, even if Bruce Eckel // and the publisher have been advised of the // possibility of such damages. Should the software // prove defective, you assume the cost of all // necessary servicing, repair, or correction. If you // think you've found an error, please email all // modified files with clearly commented changes to: // Bruce@EckelObjects.com. (Please use the same // address for non-code errors found in the book.) ///////////////////////////////////////////////// // 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.println("a.length=" + a.length); 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); } } ///:~