【ThinkingInJava】46、把数组反序排列

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//: net/mindview/util/Generated.javapackage net.mindview.util;import java.util.*;public class Generated {  // Fill an existing array:  public static <T> T[] array(T[] a, Generator<T> gen)   {    return new CollectionData<T>(gen, a.length).toArray(a);  }  // Create a new array:  @SuppressWarnings("unchecked")  public static <T> T[] array(Class<T> type,      Generator<T> gen, int size)   {    T[] a =      (T[])java.lang.reflect.Array.newInstance(type, size);    return new CollectionData<T>(gen, size).toArray(a);  }} ///:~

package Lesson16Arrays;//: arrays/CompType.java// Implementing Comparable in a class.import java.util.*;import net.mindview.util.*;import static net.mindview.util.Print.*;public class CompType implements Comparable<CompType> {  int i;  int j;  private static int count = 1;//静态的    public CompType(int n1, int n2) //构造函数，给两个私有成员赋值  {    i = n1;    j = n2;  }    public String toString()   {    String result = "[i = " + i + ", j = " + j + "]";        if(count++ % 3 == 0)//当个数恰好是3的倍数时候换行，并++，每输出一次就++      result += "\n";    return result;  }    public int compareTo(CompType rv) //sort函数会调用这个  {    return (i < rv.i ? -1 : (i == rv.i ? 0 : 1));//要比较的对象的i比这个大的话，就返回-1  }    private static Random r = new Random(47);//私有静态的，产生    public static Generator<CompType> generator()   {    return new Generator<CompType>() {      public CompType next()       {        return new CompType(r.nextInt(100),r.nextInt(100));//在 0（包括）和指定值（不包括）之间均匀分布的 int 值      }    };  }    public static void main(String[] args)   {    CompType[] a =      Generated.array(new CompType[12], generator());//后面那个参数每次调用的时候随机产生数据，用来初始化前面那个对象    print("before sorting:");    print(Arrays.toString(a));    Arrays.sort(a);    print("after sorting:");    print(Arrays.toString(a));  }}

输出：

before sorting: obj1
[[i = 58, j = 55], [i = 93, j = 61], [i = 61, j = 29]
, [i = 68, j = 0], [i = 22, j = 7], [i = 88, j = 28]
, [i = 51, j = 89], [i = 9, j = 78], [i = 98, j = 61]
, [i = 20, j = 58], [i = 16, j = 40], [i = 11, j = 22]
] obj1
after sorting: obj1
[[i = 98, j = 61], [i = 93, j = 61], [i = 88, j = 28]
, [i = 68, j = 0], [i = 61, j = 29], [i = 58, j = 55]
, [i = 51, j = 89], [i = 22, j = 7], [i = 20, j = 58]
, [i = 16, j = 40], [i = 11, j = 22], [i = 9, j = 78]
] obj1

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