Java對象排序的3種實現方式

/**


Java對象排序的3種實現方式
@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)實現，必須實現Comparator的一個比較器并復寫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)類來比較：");
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[])實現,對象必須實現Comparable接口并復寫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[])類來比較：");
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)實現，對象必須實現Comparable接口并復寫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)類來比較：");
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;
 }

 }
}</pre>