Java遍历ListMap的集中方法

Posted 2020-11-23

使用JDK8新特性，for循环增强，Iterator，while做遍历List集合

    public static void main(String[] args) {

        List<String> list = new ArrayList<>();
        list.add("test1x");
        list.add("test2x");
        list.add("test3x");
        System.out.println(list);

        System.out.println("===========");
        list.forEach((v)->{
            System.out.println(v);
        });

        System.out.println("===========");
        for(String str : list) {
            System.out.println(str);
        }

        System.out.println("=====================");
        for(int i = 0; i < list.size();i++) {
            System.out.println(list.get(i));
        }

        System.out.println("====================");
        Iterator<String> it = list.iterator();
        while(it.hasNext()) {
            System.out.println(it.next());
        }

        System.out.println("===================");
        int i = 0;
        while(i < list.size()){
            System.out.println(list.get(i));
            i++;
        }

    }

 

使用JDK8新特性，for循环增强，Iterator，Map.Entry<K,V>做遍历Map集合

public static void main(String[] args) {

        Map<Integer,String> map = new HashMap<>();
        map.put(1,"test1x");
        map.put(2,"test2x");
        map.put(3,"test3x");
        System.out.println(map);

        System.out.println("==========================");
        map.forEach((k ,v) -> {
                System.out.println(k + " , " + v);
        });

        System.out.println("========================");
        for(Map.Entry<Integer,String> entry : map.entrySet()) {
            System.out.println(entry.getKey() + " , " + entry.getValue());
        }

        System.out.println("====================");
        for(int key : map.keySet()) {
            System.out.println(key + " , " + map.get(key));
        }

        System.out.println("===================");
        Iterator<Map.Entry<Integer,String>> it 
          = map.entrySet().iterator();
        while(it.hasNext()){
            Map.Entry<Integer, String> entry = it.next();
            System.out.println(entry.getKey() + " , " + entry.getValue());
        }

        System.out.println("=====================");
        for(String v : map.values()) {
            System.out.println(v);
        }
    }