三种接口实现增删改查

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();
    }
}

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();
    }
}

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();
    }
}