Java Comparator用法 Java中实现Comparator接口和用法实例（简明易懂）

package com.ljq.entity;


/**
 * 运号单流程
 * 
 * @author Administrator
 * 
 */
public class Step{
  /** 处理时间 */
  private String acceptTime = "";
  /** 快件所在地点 */
  private String acceptAddress = "";

  public Step() {
    super();
  }

  public Step(String acceptTime, String acceptAddress) {
    super();
    this.acceptTime = acceptTime;
    this.acceptAddress = acceptAddress;
  }

  public String getAcceptTime() {
    return acceptTime;
  }

  public void setAcceptTime(String acceptTime) {
    this.acceptTime = acceptTime;
  }

  public String getAcceptAddress() {
    return acceptAddress;
  }

  public void setAcceptAddress(String acceptAddress) {
    this.acceptAddress = acceptAddress;
  }

}

package com.ljq.entity;

import java.util.Comparator;
import java.util.Date;

import com.ljq.util.UtilTool;

/**
 * 对Step类进行排序
 * 
 * @author Administrator
 *
 */
public class StepComparator implements Comparator<Step>{

  /**
   * 如果o1小于o2,返回一个负数;如果o1大于o2，返回一个正数;如果他们相等，则返回0;
   */
  @Override
  public int compare(Step o1, Step o2) {
    Date acceptTime1=UtilTool.strToDate(o1.getAcceptTime(), null);
    Date acceptTime2=UtilTool.strToDate(o2.getAcceptTime(), null);
    
    //对日期字段进行升序，如果欲降序可采用before方法
    if(acceptTime1.after(acceptTime2)) return 1;
    return -1;
  }

}

package junit;

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

import org.junit.Test;


public class StepComparatorTest {

  @Test
  public void sort() throws Exception{
    List<Step> steps=new ArrayList<Step>;
    //对集合对象进行排序
     StepComparator comparator=new StepComparator();
    Collections.sort(steps, comparator);
    if(steps!=null&&steps.size()>0){
      for(Step step:steps){
        System.out.println(step.getAcceptAddress());
        System.out.println(step.getAcceptTime());
      }
    }

  }
}