[转]java List 排序 Collections.sort

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java List 排序 Collections.sort

用Collections.sort方法对list排序有两种方法
第一种是list中的对象实现Comparable接口，如下：

代码:

Java代码

/**
* 根据order对User排序
*/
public class User implements Comparable<User>{
private String name;
private Integer order;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Integer getOrder() {
return order;
}
public void setOrder(Integer order) {
this.order = order;
}
public int compareTo(User arg0) {
return this.getOrder().compareTo(arg0.getOrder());
}
}
public class Test{
public static void main(String[] args) {
User user1 = new User();
user1.setName("a"); user1.setOrder(1);
User user2 = new User(); user2.setName("b");
user2.setOrder(2);
List<User> list = new ArrayList<User>();
//此处add user2再add user1
list.add(user2); list.add(user1);
Collections.sort(list);
for(User u : list){
System.out.println(u.getName());
}
}
}

/**
* 根据order对User排序
*/
public class User implements Comparable<User>{
    private String name;
    private Integer order;
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public Integer getOrder() {
        return order;
    }
    public void setOrder(Integer order) {
        this.order = order;
    }
    public int compareTo(User arg0) {
        return this.getOrder().compareTo(arg0.getOrder());
    }
}

public class Test{
    public static void main(String[] args) {
         User user1 = new User();
         user1.setName("a"); user1.setOrder(1); 
         User user2 = new User(); user2.setName("b");
         user2.setOrder(2); 
         List<User> list = new ArrayList<User>(); 
        //此处add user2再add user1 
        list.add(user2); list.add(user1); 
        Collections.sort(list); 
        for(User u : list){ 
            System.out.println(u.getName()); 
        } 
    } 
}

输出结果如下
a
b
第二种方法是根据Collections.sort重载方法来实现，例如：

代码:

Java代码