Object集合LIst根據某一個字段排序，

1.創建一個比較器類實現 java.util.Comparator 並重新compare方法，以下是根據學生和老師實體類進行創建時間排序舉例。

package com.jiliang

import java.util.Collections;
import java.util.List;

public class ComparatorList implements java.util.Comparator {
    /**
     * 根據生成時間進行排序
     * @param arg0
     * @param arg1
     * @return
     */
    @Override
    public int compare(Object arg0, Object arg1) {
        Student cb ;
        Teacher rd ;
        Student cb1 ;
        Teacher rd1 ;
        if(arg0 instanceof Student){
            cb=(Student)arg0;
            if(arg1 instanceof Teacher){
                rd=(Teacher)arg1;
                return cb.getCreateTime().compareTo(rd.getCreateTime());
            }else{
                cb1=(Student)arg1;
                return cb.getCreateTime().compareTo(cb1.getCreateTime());
            }
        }else{
            rd1=(Teacher)arg0;
            if(arg1 instanceof Teacher){
                rd=(Teacher)arg1;
                return rd1.getCreateTime().compareTo(rd.getCreateTime());
            }else{
                cb=(Student)arg1;
                return rd1.getCreateTime().compareTo(cb.getCreateTime());
            }
        }
    }

}

 

public static void main(String [] args){
    //其中Object對象是student和teacher   即：array 是List<Student>和List<Teacher>集合
    List<Object> array = new ArrayList<>();
    ComparatorList comparator=new ComparatorList();
    //正排序
    Collections.sort(array, comparator);
    //逆排序
    Collections.reverse(array);
}