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java接口用法与代码 java接口通俗理解
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Java中Comparator接口的用法
在java编程中java接口用法与代码，如果要对集合对象或数组对象进行排序java接口用法与代码，需要实现Comparator接口以达到目标，用法如下（模拟下在集合对象中对日期属性进行排序）java接口用法与代码：
一、实体类Step
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;
}
}
二、实现Comparator接口
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 ComparatorStep{
/**
* 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java接口用法与代码他们相等，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;
}
}
三、代码测试
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{
ListStep steps=new ArrayListStep;
//对集合对象进行排序
StepComparator comparator=new StepComparator();
Collections.sort(steps, comparator);
if(steps!=nullsteps.size()0){
for(Step step:steps){
System.out.println(step.getAcceptAddress());
System.out.println(step.getAcceptTime());
}
}
}
}
相关问答
Q1: Java接口的定义与实现
方法的实现是指可以在{}中写具体的Java代码，接口只能是以（）结尾，
public void tree();//方法的定义
//方法的具体实现
public void tree(){
system.out.println("这是一颗松树");
}
Q2: Java程序面向对象编程的基本架构 接口的定义和使用 求完整代码……谢谢
public class Admins implements Userinterface{
private String name;
private String password;
private static int userNum;
public Admins() {
userNum ++;
}
public Admins(String name, String password) {
this.name = name;
this.password = password;
userNum ++;
}
public void setPassword(String password) {
this.password = password;
}
public String getPassword() {
return this.password;
}
public String toString() {
return "Total: " + Admins.userNum + "\nName: " + this.name + "\nPassword: " + this.password;
}
public static void main(String [] args) {
Userinterface [] users = new Userinterface[]{new Admins("jeryy", "11111"), new Admins("green", "123123")};
for(Userinterface u: users) {
System.out.println(u);
}
}
}
interface Userinterface{
public void setPassword(String password);
public String getPassword();
public String toString();
}
public class Bins{
public static void main(String [] args) {
int len = 10;
int [] dist = new int [len];
for(int i = 0; i dist.length; i ++) {
dist[i] = (int)(Math.random() * 100);
}
java.util.Arrays.sort(dist);
System.out.println("生成数组如下: ");
for(int i: dist) {
System.out.print(i + "\t");
}
java.util.Scanner san = new java.util.Scanner(System.in);
System.out.print("输入要查找的数: ");
int key = san.nextInt();
int res = Bins.binSearch(dist, key);
//System.out.println(res);
String info = (res =0 ) ? (key + ":" + res) : "查找失败";
System.out.println(info);
}
public static int binSearch(int [] dist, int key) {
java.util.Arrays.sort(dist);
return java.util.Arrays.binarySearch(dist, key);
}
}
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