Java对象排序的3种实现方式详解编程语言

/** 
 * 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; 
        } 
    } 
}