ArrayList
ArrayList 实现增删改查
package test;
import java.util.ArrayList;
import java.util.Iterator;
/**
* @Author: Mo
* @Date: 2020/12/6 11:11
*/
public class list {
ArrayList<String > list1=new ArrayList<String>();
public ArrayList<String> addMethod(){
list1.add("早饭");
list1.add("午饭");
list1.add("晚饭");
return list1;
}
public ArrayList<String> deleteMethod(){
list1.remove("早饭");
return list1;
}
public ArrayList<String> updateMethod(){
list1.set(0,"午饭多吃");
return list1;
}
public void selectMethod1(){
Iterator<String> it=list1.iterator();
while(it.hasNext())
{
String string=it.next();
System.out.print(string+"\t");
}
}
public void selectMethod2(){
for(String s:list1){
System.out.print(s+"\t");
}
}
public void selectMethod3(){
for (int i = 0; i < list1.size(); i++) {
System.out.print(list1.get(i)+"\t");
}
}
public static void main(String[] args) {
list list1=new list();
System.out.println("赖床的三餐变化:");
list1.addMethod();
list1.selectMethod1();
System.out.println();
list1.deleteMethod();
list1.selectMethod2();
System.out.println();
list1.updateMethod();
list1.selectMethod3();
}
}
HashSet
HashSet 实现增删改查
package test;
import java.util.HashSet;
import java.util.Iterator;
/**
* @Author: Mo
* @Date: 2020/12/6 11:11
*/
public class set {
HashSet<String > set1=new HashSet<String>();
public HashSet<String> addMethod(){
set1.add("早饭");
set1.add("午饭");
set1.add("晚饭");
return set1;
}
public HashSet<String> deleteMethod(){
set1.remove("早饭");
return set1;
}
public HashSet<String> updateMethod(){
set1.remove("午饭");
set1.add("午饭多吃");
return set1;
}
//迭代器遍历
public void selectMethod(){
Iterator<String> it=set1.iterator();
while(it.hasNext())
{
String string=it.next();
System.out.print(string+"\t");
}
}
/*
foreach方法 遍历
public void selectMethod(){
for(String s:set1){
System.out.print(s+"\t");
}
}
*/
public static void main(String[] args) {
set set1=new set();
System.out.println("赖床的三餐变化:");
set1.addMethod();
set1.selectMethod();
System.out.println();
set1.deleteMethod();
set1.selectMethod();
System.out.println();
set1.updateMethod();
set1.selectMethod();
}
}
HashMap
HashMap 实现增删改查
package test;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
/**
* @Author: hyy
* @Date: 2020/12/6 15:02
*/
public class map {
Map<String,String> map=new HashMap<String,String>();
public Map<String,String> addMethod(){
map.put("001","早饭");
map.put("002","午饭");
map.put("003","晚饭");
return map;
}
public Map<String,String> deleteMethod(){
map.remove("001");
return map;
}
public Map<String,String> updateMethod(){
map.remove("002");
map.put("001","多吃午饭");
return map;
}
/** 迭代器 遍历 */
public void selectMethod(){
Iterator <String> it=map.keySet().iterator();
while(it.hasNext())
{
String s1=it.next();
String name=map.get(s1);
System.out.println(s1+"\t"+name);
}
}
public void selectMethod1(){
/** foreach()方法 遍历
* Map类提供了一个称为entrySet()的方法,
* 这个方法返回一个Map.Entry实例化后的对象集
*/
for (Map.Entry<String, String> entry : map.entrySet()){
System.out.println(entry.getKey() + "\t" + entry.getValue());
}
}
public static void main(String[] args) {
map map1=new map();
map1.addMethod();
System.out.println();
map1.selectMethod();
System.out.println();
map1.deleteMethod();
System.out.println();
map1.selectMethod();
System.out.println();
map1.updateMethod();
System.out.println();
map1.selectMethod1();
}
}