Java遍历集合

场景：Java遍历集合

记录：NO.248

Java遍历集合，简洁且常用，记录一下。

1.遍历List

public static void traversalList(){
        //造数据
        List<GirlInfo> list = new ArrayList<>();
        GirlInfo girl1 = new GirlInfo("2021062101","张小姐","B");
        GirlInfo girl2 = new GirlInfo("2021062102","李小姐","C");
        GirlInfo girl3 = new GirlInfo("2021062103","刘小姐","D");
        list.add(girl1);
        list.add(girl2);
        list.add(girl3);
        //遍历方式一
        System.out.println("遍历方式一:");
        for(int i=0;i<list.size();i++){
            GirlInfo girl = list.get(i);
            System.out.println("ID号: " +girl.getId() + " ,称呼: " +girl.getName() +" , CUP: " + girl.getCup());
        }
        //遍历方式二
        System.out.println("遍历方式二:");
        for(GirlInfo girl : list){
            System.out.println("ID号: " +girl.getId() + " ,称呼: " +girl.getName() +" , CUP: " + girl.getCup());
        }
        //遍历方式三
        System.out.println("遍历方式三:");
        for(Iterator it= list.iterator();it.hasNext();){
            GirlInfo girl = (GirlInfo) it.next();
            System.out.println("ID号: " +girl.getId() + " ,称呼: " +girl.getName() +" , CUP: " + girl.getCup());
        }
        //遍历方式四
        System.out.println("遍历方式四:");
        Iterator it = list.iterator();
        while(it.hasNext()){
            GirlInfo girl = (GirlInfo) it.next();
            System.out.println("ID号: " +girl.getId() + " ,称呼: " +girl.getName() +" , CUP: " + girl.getCup());
        }
    }

2.遍历Map

public static void traversalMap(){
        //造数据
        Map<String,GirlInfo> girlInfoMap = new HashMap<String,GirlInfo>();
        GirlInfo girl1 = new GirlInfo("2021062101","张小姐","B");
        GirlInfo girl2 = new GirlInfo("2021062102","李小姐","C");
        GirlInfo girl3 = new GirlInfo("2021062103","刘小姐","D");
        girlInfoMap.put(girl1.getId(),girl1);
        girlInfoMap.put(girl2.getId(),girl2);
        girlInfoMap.put(girl3.getId(),girl3);
        //遍历方式一
        System.out.println("遍历方式一:");
        for(Map.Entry<String,GirlInfo> entry : girlInfoMap.entrySet()){
            String key = entry.getKey();
            GirlInfo girl = entry.getValue();
            System.out.println("ID号: " +girl.getId() + " ,称呼: " +girl.getName() +" , CUP: " + girl.getCup());
        }
        //遍历方式二
        System.out.println("遍历方式二:");
        for(String key : girlInfoMap.keySet()){
            System.out.println("ID号: " + key);
        }
        for(GirlInfo value : girlInfoMap.values()){
            System.out.println("ID号: " +value.getId() + " ,称呼: " +value.getName() +" , CUP: " + value.getCup());
        }
        //遍历方式三
        System.out.println("遍历方式三:");
        Iterator<Map.Entry<String,GirlInfo>> iterator =  girlInfoMap.entrySet().iterator();
        while(iterator.hasNext()){
            Map.Entry<String,GirlInfo> entry = iterator.next();
            String key = entry.getKey();
            GirlInfo girl = entry.getValue();
            System.out.println("ID号: " +girl.getId() + " ,称呼: " +girl.getName() +" , CUP: " + girl.getCup());
        }
        //遍历方式四
        System.out.println("遍历方式四:");
        for(String key : girlInfoMap.keySet()){
            GirlInfo girl = girlInfoMap.get(key);
            System.out.println("ID号: " +girl.getId() + " ,称呼: " +girl.getName() +" , CUP: " + girl.getCup());
        }
    }

3.遍历Set

public static void traversalSet(){
        Set<GirlInfo> setInfo = new HashSet<GirlInfo>();
        GirlInfo girl1 = new GirlInfo("2021062101","张小姐","B");
        GirlInfo girl2 = new GirlInfo("2021062102","李小姐","C");
        GirlInfo girl3 = new GirlInfo("2021062103","刘小姐","D");
        setInfo.add(girl1);
        setInfo.add(girl2);
        setInfo.add(girl3);
        //遍历方式一
        System.out.println("遍历方式一:");
        Iterator<GirlInfo> iterator = setInfo.iterator();
        while (iterator.hasNext()){
            GirlInfo girl = iterator.next();
            System.out.println("ID号: " +girl.getId() + " ,称呼: " +girl.getName() +" , CUP: " + girl.getCup());
        }
        //遍历方式二
        System.out.println("遍历方式二:");
        for(GirlInfo girlInfo : setInfo){
            System.out.println("ID号: " +girlInfo.getId() + " ,称呼: " +girlInfo.getName() +" , CUP: " + girlInfo.getCup());
        }
    }

4.实体对象

static class GirlInfo{

        public GirlInfo(String Id, String name, String cup) {
            this.Id = Id;
            this.name = name;
            this.cup = cup;
        }
        private String Id;
        private String name;
        private String cup;
        public String getId() {
            return Id;
        }
        public void setId(String id) {
            Id = id;
        }
        public String getName() {
            return name;
        }
        public void setName(String name) {
            this.name = name;
        }
        public String getCup() {
            return cup;
        }
        public void setCup(String cup) {
            this.cup = cup;
        }
    }

以上，感谢。