import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
/**
 * @Author: Re
 * @Date: 2020/12/6 15:39
 */
public class CurdTest01 {
    List<String> stringList=new ArrayList<>();
    public void addFunction(){
        for (int i = 0; i < 9; i++) {
            stringList.add(""+i);
        }
    }
    public void deleteFunction(){
        stringList.remove(5);
    }
    public List<String> alterFunction(){
        stringList.set(1,"5");
        return stringList;
    }
    public void getStringList(){
        System.out.println(stringList.get(6));
    }
    public void getStringList1() {
        System.out.println("使用迭代器遍历：");
        Iterator<String> it=stringList.iterator();
        while (it.hasNext()){
            String string=it.next();
            System.out.print(string+"\t");
        }
        System.out.println();
    }
    public void getStringList2(){
        System.out.println("使用for遍历：");
        for (int i = 0; i < stringList.size(); i++) {
            System.out.print(stringList.get(i)+"\t");
        }
        System.out.println();
    }
    public void getStringList3(){
        System.out.println("使用foreach遍历：");
        for(String list:stringList){
            System.out.print(list+"\t");
        }
        System.out.println();
    }
    public static void main(String[] args) {
        CurdTest01 curdTest01=new CurdTest01();
        curdTest01.addFunction();
        curdTest01.getStringList1();
        curdTest01.deleteFunction();
        curdTest01.getStringList2();
        curdTest01.alterFunction();
        curdTest01.getStringList3();
        curdTest01.getStringList();
    }
}

import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;
/**
 * @Author: Re
 * @Date: 2020/12/6 16:46
 */
public class CurdTest02 {
    Set<String> stringSet=new HashSet<>();
    public void addFunction(){
        for (int i = 0; i < 9; i++) {
            stringSet.add(""+i);
        }
    }
    public void deleteFunction(){
        stringSet.remove(5);
    }
    public void alterFunction(String oldDate,String newDate){
        stringSet.remove(oldDate);
        stringSet.add(newDate);
    }
    public void getFunction1(){
        System.out.println("使用迭代器遍历:");
        Iterator<String> it=stringSet.iterator();
        while(it.hasNext()){
            System.out.print(it.next()+"\t");
        }
        System.out.println();
    }
    public void getFunction2(){
        System.out.println("使用foreach遍历:");
        for (String list:stringSet) {
            System.out.print(list+"\t");
        }
        System.out.println();
    }
    public static void main(String[] args) {
        CurdTest02 curdTest02=new CurdTest02();
        curdTest02.addFunction();
        curdTest02.getFunction1();
        curdTest02.alterFunction("5","4");
        curdTest02.getFunction2();
        curdTest02.deleteFunction();
        curdTest02.getFunction1();
    }
}

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
/**
 * @Author: Re
 * @Date: 2020/12/6 17:03
 */
public class CurdTest03 {
    Map<Integer,String> integerStringMap=new HashMap<>();
    public void addFunction(){
        integerStringMap.put(1,"张三");
        integerStringMap.put(2,"李四");
        integerStringMap.put(3,"王五");
        }
    public void deleteFunction(){
        integerStringMap.remove(3);
    }
    public void alterFunction(){
        integerStringMap.put(1,"小二");
    }
    public void getFunction1(){
        System.out.println("用foreach遍历：");
        for (Integer key:integerStringMap.keySet()) {
            System.out.println(key+"="+integerStringMap.get(key));
        }
        System.out.println();
    }
    public void getFunction2(){
        System.out.println("利用迭代器遍历：");
        Set<Map.Entry<Integer,String>> entrySet=integerStringMap.entrySet();
        Iterator it=entrySet.iterator();
        while(it.hasNext()){
            System.out.println(it.next());
        }
        System.out.println();
    }
    public static void main(String[] args) {
        CurdTest03 curdTest03=new CurdTest03();
        curdTest03.addFunction();
        curdTest03.getFunction1();
        curdTest03.alterFunction();
        curdTest03.getFunction2();
        curdTest03.deleteFunction();
        curdTest03.getFunction2();
    }
}