multidimarray.java

Java编程思想 第四课 全代码

//: c04:MultiDimArray.java
// From 'Thinking in Java, 2nd ed.' by Bruce Eckel
// www.BruceEckel.com. See copyright notice in CopyRight.txt.
// Creating multidimensional arrays.
import java.util.*;

public class MultiDimArray {
  static Random rand = new Random();
  static int pRand(int mod) {
    return Math.abs(rand.nextInt()) % mod + 1;
  }
  static void prt(String s) {
    System.out.println(s);
  }
  public static void main(String[] args) {
    int[][] a1 = {
      { 1, 2, 3, },
      { 4, 5, 6, },
    };
   prt("a1.length :"+a1.length);
   
    for(int i = 0; i < a1.length; i++)
      for(int j = 0; j < a1[i].length; j++)
        
        prt("a1[" + i + "][" + j + "] = " + a1[i][j]+ "\n   a1[i].length: " +a1[i].length);
    // 3-D array with fixed length:
    int[][][] a2 = new int[2][2][4];
    prt("a2.length :"+a2.length);
    for(int i = 0; i < a2.length; i++)
      for(int j = 0; j < a2[i].length; j++)
        for(int k = 0; k < a2[i][j].length;
            k++)
          prt("a2[" + i + "][" + j + "][" + k + "] = " + a2[i][j][k]+ "\n   a2[i].length: " +a2[i].length);
    // 3-D array with varied-length vectors:
    int[][][] a3 = new int[pRand(7)][][];
    prt("a3.length :"+a3.length);
    for(int i = 0; i < a3.length; i++) {
      a3[i] = new int[pRand(5)][];
      for(int j = 0; j < a3[i].length; j++)
        a3[i][j] = new int[pRand(5)];
    }
    for(int i = 0; i < a3.length; i++)
      for(int j = 0; j < a3[i].length; j++)
        for(int k = 0; k < a3[i][j].length;
            k++)
          prt("a3[" + i + "][" +
              j + "][" + k +
              "] = " + a3[i][j][k]+ "\n   a3[i].length: " +a3[i].length);
    // Array of nonprimitive objects:
    Integer[][] a4 = {
      { new Integer(1), new Integer(2)},
      { new Integer(3), new Integer(4)},
      { new Integer(5), new Integer(6)},
    };
    prt("a4.length :"+a4.length);
    for(int i = 0; i < a4.length; i++)
      for(int j = 0; j < a4[i].length; j++)
        prt("a4[" + i + "][" + j +
            "] = " + a4[i][j]+ "\n   a4[i].length: " +a4[i].length);
    Integer[][] a5;
    a5 = new Integer[3][];
    prt("a5.length :"+a5.length);
    for(int i = 0; i < a5.length; i++) {
      a5[i] = new Integer[3];
      for(int j = 0; j < a5[i].length; j++)
        a5[i][j] = new Integer(i*j);
    }
    for(int i = 0; i < a5.length; i++)
      for(int j = 0; j < a5[i].length; j++)
        prt("a5[" + i + "][" + j +
            "] = " + a5[i][j]+ "\n   a5[i].length: " +a5[i].length+
            "\n   a5[j].length: " +a5[j].length);
  }
} ///:~