字符串处理,map使用 key value迭代器使用,switch使用

字符串处理,map使用 key value迭代器使用,switch使用

代码语言：javascript复制

package com.example.core.mydemo.java2;

import java.util.*;

public class SwitchTest {
    public static void main(String[] args) {
        //switch使用
        /**
         * output:
         * convertCouponType1=A
         * convertCouponType2=B
         * convertCouponType3=C
         * convertCouponType4=B
         */
        System.out.println("convertCouponType1="   convertCouponType("1"));
        System.out.println("convertCouponType2="   convertCouponType("2"));
        System.out.println("convertCouponType3="   convertCouponType("3"));
        System.out.println("convertCouponType4="   convertCouponType("4"));

        //字符串处理
        String s1 = "上海 aaa 1";
        String s2 = "北京 aaa 1";
        String s3 = "深圳 ccc 3";

        List<String>  list = new ArrayList<String>();
        list.add(s1);
        list.add(s2);
        list.add(s3);

        int idx0 = s1.indexOf(" ");
        /**
         * output:
         * idx0=2
         * idx1= aaa 1
         * idx2=上海
         */
        System.out.println("idx0="   idx0);
        System.out.println("idx1="   s1.substring(idx0));
        System.out.println("idx2="   s1.substring(0,idx0));

        /**
         * 解析的字符串，后面不变的是 key,前面城市的是value
         */
        Map<String,String> map = new HashMap<>();
        for (String ss : list) {
            int idx = ss.indexOf(" ");
            if(map.containsKey(ss.substring(idx))){
                map.put(ss.substring(idx), map.get(ss.substring(idx))   "/"   ss.substring(0, idx));
            }else{
                map.put(ss.substring(idx), ss.substring(0, idx));
            }
        }
        /**
         * output:
         * map={ ccc 3=深圳,  aaa 1=上海/北京}
         */
        System.out.println("map="   map);

        //map判断是否存在key
//        map.put("aaa","上海");
//        if(map.containsKey("aaa")) {
//            map.put("aaa", map.get("aaa") "/" "北京");
//        }

        /**
         * 数据还原
         */
        List<String> handleList = new ArrayList<>();
        Iterator iter = map.keySet().iterator();
        while(iter.hasNext()){
            String key = (String)iter.next();
            //还原：将value 城市   key 后面不变的字符
            /**
             * output:
             * test=深圳 ccc 3
             * test=上海/北京 aaa 1
             */
            System.out.println("test="   map.get(key)   key);
            handleList.add(map.get(key)   key);
        }
        /**
         * handleList=[深圳 ccc 3, 上海/北京 aaa 1]
         */
        System.out.println("handleList="   handleList);
    }

    private static String convertCouponType(String couponTypeParam) {
        switch (couponTypeParam){
            case "1":
                return "A";
            case "2":
                return "B";
            case "3":
                return "C";
        }
        return "B";
    }
}

代码语言：javascript复制

package com.example.core.mydemo.java;


import java.util.*;

/**
 * output:
 * map2={carPlatNum2=车B6991B2, CarPlatNum=车B6991B, carPlatNum=车B6991B}
 * entity1=车B6991B2
 * entity1=车B6991B
 * entity1=车B6991B
 * entity2=车B6991B2
 * entity2=车B6991B
 * entity2=车B6991B
 */
public class MapTest {
    public static void main(String[] args) {
        Map map = new HashMap();
        map.put("carPlatNum","车B6991B");
        map.put("CarPlatNum","车B6991B");
        Map map2 = new HashMap();
        map2.put("carPlatNum2","车B6991B2");
        map2.put("CarPlatNum","车B6991B2");

//        map.putAll(map2);
//        //output: map={CarPlatNum=车B6991B2, carPlatNum2=车B6991B2, carPlatNum=车B6991B}
//        System.out.println("map="   map);

        map2.putAll(map);
        //output:  map2={carPlatNum2=车B6991B2, CarPlatNum=车B6991B, carPlatNum=车B6991B}
        System.out.println("map2="   map2);

        Set set = map2.keySet();
        Iterator<String> iterator = set.iterator();
        while(iterator != null && iterator.hasNext()) {
            String key = iterator.next();
            System.out.println("entity1="   map2.get(key));
        }

        //根据值遍历
        Collection set2 = map2.values();
        Iterator<String> iterator2 = set2.iterator();
        while(iterator2 != null && iterator2.hasNext()) {
            String entity = iterator2.next();
            System.out.println("entity2="   entity);
        }
    }
}

map string system 字符串 key

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