/**   * Java对象排序的3种实现方式   * @author zhangwenzhang   *   */  public class TestObjectSort {      /**       * @param args       */      public static void main(String[] args) {          // TODO Auto-generated method stub          /**方法1           * 使用Collections.sort(List, Comparator)实现，必须实现Comparator的一个比较器并复写compare()方法           */          Person1[] ps = new Person1[]{new Person1("p0",0),                                       new Person1("p1",3),                                       new Person1("p2",5),                                       new Person1("p3",4),                                       new Person1("p4",8),                                       new Person1("p5",6),                                       new Person1("p6",7),                                       new Person1("p7",1),                                       new Person1("p8",2),                                       new Person1("p9",9)};          List<Person1> pl = new ArrayList<Person1>();          for(int i = 0; i < 10; i++){              System.out.print(ps[i].getAge());              pl.add(ps[i]);          }          System.out.println("\n使用Collections.sort(List, Comparator)类来比较：");          long l1 = System.currentTimeMillis();          Collections.sort(pl, new MyComparator());          System.out.println("time: " + (System.currentTimeMillis() - l1));          for(Iterator it = pl.iterator(); it.hasNext();){              Person1 p = (Person1) it.next();              System.out.print(p.getAge());          }          /**方法2           * 使用Arrays.sort(Object[])实现,对象必须实现Comparable接口并复写compareTo()方法           */          Person2[] ps2 = new Person2[]{new Person2("p0",0),                                       new Person2("p1",3),                                       new Person2("p2",5),                                       new Person2("p3",4),                                       new Person2("p4",8),                                       new Person2("p5",6),                                       new Person2("p6",7),                                       new Person2("p7",1),                                       new Person2("p8",2),                                       new Person2("p9",9)};          System.out.println("\n使用Arrays.sort(Object[])类来比较：");          long l2 = System.currentTimeMillis();          Arrays.sort(ps2);          System.out.println("time: " + (System.currentTimeMillis() - l2));          for(int i = 0; i < 10; i++){              System.out.print(ps2[i].getAge());          }          /**方法3           * 使用Collections.sort(List)实现，对象必须实现Comparable接口并复写compareTo()方法           */          Person2[] ps3 = new Person2[]{new Person2("p0",0),                                       new Person2("p1",3),                                       new Person2("p2",5),                                       new Person2("p3",4),                                       new Person2("p4",8),                                       new Person2("p5",6),                                       new Person2("p6",7),                                       new Person2("p7",1),                                       new Person2("p8",2),                                       new Person2("p9",9)};          List<Person2> pl3 = new ArrayList<Person2>();          for(int i = 0; i < 10; i++){              pl3.add(ps3[i]);          }          System.out.println("\n使用Collections.sort(List)类来比较：");          Collections.sort(pl3);          for(Iterator it = pl3.iterator(); it.hasNext();){              Person2 p = (Person2) it.next();              System.out.print(p.getAge());          }      }  }  /**   * 方法1需要   * @author zhangwenzhang   *   */  class MyComparator implements Comparator{      public int compare(Object o1, Object o2){          Person1 p1 = (Person1)o1;          Person1 p2 = (Person1)o2;          if(p1.getAge() < p2.getAge()){              return -1;          }else if(p1.getAge() == p2.getAge()){              return 0;          }else{              return 1;          }      }  }  /**   * 方法1需要   * @author zhangwenzhang   *   */  class Person1{      private String name;      private int age;      public Person1(){}      public Person1(String name, int age) {          super();          this.name = name;          this.age = age;      }      public String getName() {          return name;      }      public void setName(String name) {          this.name = name;      }      public int getAge() {          return age;      }      public void setAge(int age) {          this.age = age;      }  }  /**   * 方法2,3需要   * @author zhangwenzhang   *   */  class Person2 implements Comparable{      private String name;      private int age;      public Person2(){}      public Person2(String name, int age) {          super();          this.name = name;          this.age = age;      }      public String getName() {          return name;      }      public void setName(String name) {          this.name = name;      }      public int getAge() {          return age;      }      public void setAge(int age) {          this.age = age;      }      public int compareTo(Object o){          Person2 p = (Person2)o;          if(this.age < p.age){              return -1;          }else if(this.age == p.age){              return 0;          }else{              return 1;          }      }  }