Android Java List 排序 – Android移動開發技術文章_手機開發 Android移動開發教學課程

原文章轉自網上blog,但是其中代碼運行後原來的list排序根本沒有改變。

於是打開Comparator文檔看瞭,發現原代碼的compare函數實現的返回值有問題!

修正後運行結果正確瞭,代碼如下:

 

@SuppressWarnings("unchecked") 
void test() { 
    ArrayList list = new ArrayList(); 
    list.add(new Person("lcl 28", 28)); 
    list.add(new Person("fx 23", 23)); 
    list.add(new Person("wqx 29", 29)); 
    list.add(new Person("qd 20", 20)); 
    list.add(new Person("xgw 69", 69)); 
    Comparator comp = new Comparator() { 
        public int compare(Object o1, Object o2) { 
            Person p1 = (Person) o1; 
            Person p2 = (Person) o2; 
            if (p1.age < p2.age) 
                return -1; 
            else if (p1.age == p2.age) 
                return 0; 
            else if (p1.age > p2.age) 
                return 1; 
            return 0; 
        } 
    }; 
    Collections.sort(list, comp); 
 
    for (int i = 0; i < list.size(); i++) { 
        Person p = (Person) list.get(i); 
        System.out.println(p.getName()); 
    } 

 
public static class Person { 
 
    private int age; 
    private String name; 
 
    public Person(String name, int age) { 
        this.age = age; 
        this.name = name; 
    } 
 
    public int getAge() { 
        return age; 
    } 
 
    public void setAge(int age) { 
        this.age = age; 
    } 
 
    public String getName() { 
        return name; 
    } 
 
    public void setName(String name) { 
        this.name = name; 
    } 
}  www.aiwalls.com
 @SuppressWarnings("unchecked")
 void test() {
  ArrayList list = new ArrayList();
  list.add(new Person("lcl 28", 28));
  list.add(new Person("fx 23", 23));
  list.add(new Person("wqx 29", 29));
  list.add(new Person("qd 20", 20));
  list.add(new Person("xgw 69", 69));
  Comparator comp = new Comparator() {
   public int compare(Object o1, Object o2) {
    Person p1 = (Person) o1;
    Person p2 = (Person) o2;
    if (p1.age < p2.age)
     return -1;
    else if (p1.age == p2.age)
     return 0;
    else if (p1.age > p2.age)
     return 1;
    return 0;
   }
  };
  Collections.sort(list, comp);

  for (int i = 0; i < list.size(); i++) {
   Person p = (Person) list.get(i);
   System.out.println(p.getName());
  }
 }

 public static class Person {

  private int age;
  private String name;

  public Person(String name, int age) {
   this.age = age;
   this.name = name;
  }

  public int getAge() {
   return age;
  }

  public void setAge(int age) {
   this.age = age;
  }

  public String getName() {
   return name;
  }

  public void setName(String name) {
   this.name = name;
  }
 }

 

摘自 michaelpp的專欄

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