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());      }    }  }}