集合 数组 遍历 总结

String[] arr = { "包青天", "白乾涛", "baiqiantao", "bqt", "0909082401", };
for (int i = 0; i < arr.length; i++) {//普通for            System.out.println("第" + (i + 1) + "个元素为：" + arr[i]);        }        for (String i : arr) {//增强for            System.out.println("元素为：" + i);        }

List<String> mList = new ArrayList<String>();        mList.add("包青天a");        mList.add("包青天c");        mList.add("包青天b");        System.out.println(mList); //[包青天a, 包青天c, 包青天b]        for (String string : mList) {//增强for            System.out.println("---" + string);        }        Iterator<String> it = mList.iterator();        while (it.hasNext()) {//迭代器            System.out.println(it.next());        }        //list特有的ListIterator，可以双向遍历        ListIterator<String> it2 = mList.listIterator();        while (it2.hasNext()) {//List迭代器            System.out.println("*******" + it2.next());//执行完后指针移到了最后，这有这样才能使用hasPrevious遍历        }        while (it2.hasPrevious()) {//List迭代器            System.out.println(it2.previous() + "*****");        }

Map<Integer, String> map = new HashMap<Integer, String>();        map.put(30, "zhagsan");        map.put(17, "李四");        map.put(2016, "包青天");        System.out.println(map);//{17=李四, 2016=包青天, 30=zhagsan}        for (Integer key : map.keySet()) {//增强for遍历key            String value = map.get(key);            System.out.println(key + "---" + value);        }        for (Map.Entry<Integer, String> k_v : map.entrySet()) {//增强for遍历键值对            System.out.println(k_v);//17=李四        }        Iterator<Integer> iterator = map.keySet().iterator();        while (iterator.hasNext()) {//健的Set集合的迭代器            Integer key = iterator.next();            String value = map.get(key);            System.out.println(key + ":" + value);        }        Iterator<Map.Entry<Integer, String>> iterator2 = map.entrySet().iterator();        while (iterator2.hasNext()) {//键值对的迭代器            System.out.println(iterator2.next());//17=李四        }

ArrayList<HashMap<String, String>> array = new ArrayList<HashMap<String, String>>();        HashMap<String, String> hm1 = new HashMap<String, String>();        hm1.put("周瑜", "小乔");        hm1.put("吕布", "貂蝉");        // 把元素添加到array里面        array.add(hm1);        HashMap<String, String> hm2 = new HashMap<String, String>();        hm2.put("郭靖", "黄蓉");        hm2.put("杨过", "小龙女");        // 把元素添加到array里面        array.add(hm2);        // 遍历        for (HashMap<String, String> hm : array) {            Set<String> set = hm.keySet();            for (String key : set) {                String value = hm.get(key);                System.out.println(key + "-" + value);            }            System.out.println("//**************************");        }    }

HashMap<String, HashMap<String, Integer>> mMap = new HashMap<String, HashMap<String, Integer>>();        HashMap<String, Integer> jcMap = new HashMap<String, Integer>();        jcMap.put("陈玉楼", 20);        jcMap.put("高跃", 22);        mMap.put("基础班", jcMap);        HashMap<String, Integer> jyMap = new HashMap<String, Integer>();        jyMap.put("李杰", 21);        jyMap.put("曹石磊", 23);        mMap.put("就业班", jyMap);        //遍历集合        Set<String> mKeySet = mMap.keySet();        for (String mKey : mKeySet) {            System.out.println(mKey);            HashMap<String, Integer> mValue = mMap.get(mKey);            Set<String> mValueKeySet = mValue.keySet();            for (String mValueKey : mValueKeySet) {                Integer mValueValue = mValue.get(mValueKey);                System.out.println("\t" + mValueKey + "-" + mValueValue);            }        }

HashMap<String, ArrayList<String>> hashMap = new HashMap<String, ArrayList<String>>();        ArrayList<String> array1 = new ArrayList<String>();        array1.add("吕布");        array1.add("周瑜");        array1.add("包青天");        hashMap.put("三国演义人物", array1);        ArrayList<String> array2 = new ArrayList<String>();        array2.add("令狐冲");        array2.add("林平之");        array2.add("包青天");        hashMap.put("笑傲江湖人物", array2);        //遍历集合        Set<String> keySet = hashMap.keySet();        for (String key : keySet) {            System.out.println(key);            ArrayList<String> valueList = hashMap.get(key);            for (String string : valueList) {                System.out.println("\t" + string);            }        }

HashMap<String, HashMap<String, ArrayList<Student>>> mMap = new HashMap<String, HashMap<String, ArrayList<Student>>>();        // 北京校区数据        HashMap<String, ArrayList<Student>> bjmMap = new HashMap<String, ArrayList<Student>>();        ArrayList<Student> array1 = new ArrayList<Student>();        Student s1 = new Student("林青霞", 27);        Student s2 = new Student("风清扬", 30);        array1.add(s1);        array1.add(s2);        ArrayList<Student> array2 = new ArrayList<Student>();        Student s3 = new Student("赵雅芝", 28);        Student s4 = new Student("武鑫", 29);        array2.add(s3);        array2.add(s4);        bjmMap.put("基础班", array1);        bjmMap.put("就业班", array2);        mMap.put("北京校区", bjmMap);        // 广州校区数据        HashMap<String, ArrayList<Student>> xamMap = new HashMap<String, ArrayList<Student>>();        ArrayList<Student> array3 = new ArrayList<Student>();        Student s5 = new Student("范冰冰", 27);        Student s6 = new Student("刘意", 30);        array3.add(s5);        array3.add(s6);        ArrayList<Student> array4 = new ArrayList<Student>();        Student s7 = new Student("李冰冰", 28);        Student s8 = new Student("张志豪", 29);        array4.add(s7);        array4.add(s8);        xamMap.put("基础班", array3);        xamMap.put("就业班", array4);        mMap.put("广州校区", xamMap);        // 遍历集合        Set<String> mMapSet = mMap.keySet();        for (String mMapKey : mMapSet) {            System.out.println(mMapKey);            HashMap<String, ArrayList<Student>> mMapValue = mMap.get(mMapKey);            Set<String> mMapValueSet = mMapValue.keySet();            for (String mMapValueKey : mMapValueSet) {                System.out.println("\t" + mMapValueKey);                ArrayList<Student> mMapValueValue = mMapValue.get(mMapValueKey);                for (Student s : mMapValueValue) {                    System.out.println("\t\t" + s.getName() + "-" + s.getAge());                }            }        }