【遍历集合】Java遍历List,Map,Vector，Set的几种方法

Z时代
2024-01-10
分类：综合

java

关于list,map,set的区别参考http://www.cnblogs.com/qlqwjy/p/7406573.html

1.遍历list

    @Test
    public void testList() {
        List<Integer> list = new ArrayList<Integer>();
        list.add(1);
        list.add(2);
        System.out.println("-------------------list------------------");
        System.out.println("-------增强for循环list----");
        for (int i : list) {
            System.out.println(i);
        }
        System.out.println("-------for循环list----");
        for (int i = 0; i < list.size(); i++) {
            System.out.println(list.get(i));
        }
        System.out.println("-------迭代器遍历list----");
        Iterator<Integer> iterator = list.iterator();
        while (iterator.hasNext()) {
            System.out.println(iterator.next());
        }
    }

结果:

-------------------list------------------

-------增强for循环list----

-------for循环list----

-------迭代器遍历list----

2.遍历Map

    @Test
    public void testMap() {
        Map<Integer, String> m = new HashMap<Integer, String>();
        m.put(1, "s");
        m.put(2, "s");
        m.put(3, "s");
        m.put(4, "s");
        System.out.println("-------------------map------------------");
        System.out.println("--------循环遍历键取值---------");
        for (Map.Entry<Integer, String> entry : m.entrySet()) {
            System.out.println(entry.getKey() + "   " + entry.getValue());
        }
        System.out.println("--------根据键取值(键正好为整数)---------");
        for (int i = 0; i < m.size(); i++) {
            System.out.println(m.get(i + 1));
        }
    }

-------------------map------------------

--------循环遍历键取值---------

1 s

2 s

3 s

4 s

--------根据键取值(键正好为整数)---------

map.entrySet方法:(将键值对存到set集合中)

Map.EntrySet接口:

3.遍历Set

    @Test
    public void testSet() {
        Set<Integer> set = new HashSet();
        set.add(1);
        set.add(2);
        System.out.println("-------------------set------------------");
        System.out.println("-------增强for循环----");
        for (int i : set) {
            System.out.println(i);
        }
        System.out.println("-------迭代器遍历----");
        Iterator<Integer> iterator = set.iterator();
        while (iterator.hasNext()) {
            System.out.println(iterator.next());
        }
    }

-------------------set------------------

-------增强for循环----

-------迭代器遍历----

4.遍历vector

    @Test
    public void testVector() {
        System.out.println("-------------------vector------------------");
        Vector<String> v = new Vector<String>();
        v.add("sss");
        v.add("sssss");
        System.out.println("-------普通for循环----");
        for (int i = 0; i < v.size(); i++) {
            System.out.println(v.get(i));
        }
        System.out.println("-------增强for循环----");
        for (String x : v) {
            System.out.println(x);
        }
        System.out.println("-------迭代器遍历----");
        Iterator<String> iterator = v.iterator();
        while (iterator.hasNext()) {
            System.out.println(iterator.next());
        }
    }