java 自定义类比较器 java 自定义类比较器代码

package com.myfile;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;

/**
 * Created by tengfei on 2017/10/27
 */
public class CompareTest {
  /**
   * 内部比较器：Comparable, 重写conpareTo方法
   */
  @SuppressWarnings("rawtypes")
  class Student1 implements Comparable {
    private String name;
    private int age;

    public Student1(int age, String name) {
      this.age = age;
      this.name = name;
    }

    @Override
    public String toString() {
      return "\tStudent1 age: " + age + ", name: " + name + "\r";
    }

    @Override
    public int compareTo(Object o) {
      Student1 tmp = (Student1) o;
      int result = tmp.age < age ? 1 : (tmp.age == age ? 0 : -1);
      return result = result == 0 ? (tmp.name.trim().compareTo(name.trim()) < 0 ? 1 : -1) : result;
    }
  }

  // -------------------------------------------------------------------------------------

  /**
   * 外部比较器：Comparator, 定义comparator比较类
   */
  class Student2 {
    private String name;
    private int age;

    public Student2(int age, String name) {
      this.age = age;
      this.name = name;
    }

    @Override
    public String toString() {
      return "\tStudent2 age: " + age + ", name: " + name + "\r";
    }
  }

  @SuppressWarnings("rawtypes")
  public static class Student2Comparator implements Comparator {
    public int compare(Object o1, Object o2) {
      Student2 t1 = (Student2) o1;
      Student2 t2 = (Student2) o2;
      int result = t1.age > t2.age ? 1 : (t1.age == t2.age ? 0 : -1);
      return result = result == 0 ? (t1.name.trim().compareTo(t2.name.trim()) > 0 ? 1 : -1) : result;
    }

    @SuppressWarnings("unchecked")
    public static void main(String[] args) {
      CompareTest co = new CompareTest();
      List<Student1> list1 = new ArrayList<Student1>();
      list1.add(co.new Student1(1, "aa"));
      list1.add(co.new Student1(2, "abb"));
      list1.add(co.new Student1(2, "acc"));
      list1.add(co.new Student1(3, "dd"));
      Collections.sort(list1); // 内部比较器:要排序的对象实现Comparable接口,可以对自身进行比较
      System.out.println(list1);

      List<Student2> list2 = new ArrayList<Student2>();
      list2.add(co.new Student2(1, "aa"));
      list2.add(co.new Student2(2, "abb"));
      list2.add(co.new Student2(2, "acc"));
      list2.add(co.new Student2(3, "dd"));
      Collections.sort(list2, new Student2Comparator()); // 外部比较器:通过实现Comparator接口
      System.out.println(list2);
    }
  }
}

List<Map<String, Object>> list = new ArrayList<>();
Map<String, Object> yuan = new HashMap<>();
yuan.put("type", 7);
yuan.put("code", "c");
Map<String, Object> jia = new HashMap<>();
jia.put("type", 1);
jia.put("code", "b");
Map<String, Object> min = new HashMap<>();
min.put("type", 6);
min.put("code", "a");
Map<String, Object> min2 = new HashMap<>();
min2.put("type", 5);
min2.put("code", "d");
Map<String, Object> min3 = new HashMap<>();
min3.put("type", 8);
min3.put("code", "e");
Map<String, Object> min4 = new HashMap<>();
min4.put("type", 7);
min4.put("code", "h");
Map<String, Object> min5 = new HashMap<>();
min5.put("type", 7);
min5.put("code", "f");

System.out.println("tttttttttttttttt"+min5.get("type"));

list.add(min);//6 a
list.add(min2);//5 d
list.add(min3);//8 e
list.add(min4);//7 h
list.add(min5);//7 f
list.add(jia);//1 b
list.add(yuan);//7 c

System.out.println(list);
 Collections.sort(list, new Comparator<Map<String, Object>>() {
 
  @Override
  public int compare(Map<String, Object> o1, Map<String, Object> o2) {
  System.out.println("o1="+o1);
  System.out.println("o2="+o2);//== null ? "" : o1.get("name").toString()
  String a = (o1.get("Tsype") == null ? "" : o1.get("TYspe").toString()).indexOf("7")+"";
  System.out.println("TYpe="+o1.get("type")+"   a="+a);
  String b = (o2.get("TYpe") == null ? "" : o2.get("TYpe").toString()).indexOf("7")+"";
  
  System.out.println("type="+o2.get("type")+"   b="+b);
  System.out.println();
  if (a.equals(b)) {
   System.out.println("o1.code="+o1.get("code"));
   System.out.println("o2.code="+o2.get("code"));
   System.out.println((o2.get("code")+"").compareTo(o1.get("code")+ ""));
   System.out.println("===============================================");
   return (o2.get("code")+"").compareTo(o1.get("code")+ "");
  }
  System.out.println( b.compareTo(a));
  System.out.println("---------------------------------------------------");
  return b.compareTo(a);
  }
 });
 System.out.println("最后显示的list="+list);
 }