集合的遍历

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遍历数组

public static void main(String[] args) {// 遍历数组：String[] arr = new String[] { "xx", "yy", "zz" };// 1，增强的for循环for (String elt : arr) {System.out.println(elt);}// 2，下标的方式for (int i = 0; i < arr.length; i++) {System.out.println(arr[i]);}}

遍历list

public static void main(String[] args) {// 遍历List：List<String> list = new ArrayList<String>();list.add("aa");list.add("bb");list.add("cc");// 1，增强的for循环for (String elt : list) {System.out.println(elt);}// 2，下标for (int i = 0; i < list.size(); i++) {System.out.println(list.get(i));}// 3，迭代器for (Iterator<String> iter = list.iterator(); iter.hasNext();) {String elt = iter.next();System.out.println(elt);}}

遍历set

public static void main(String[] args) {// 遍历Set：Set<String> set = new HashSet<String>();set.add("dd");set.add("ee");set.add("ff");// 1，增强的for循环for (String elt : set) {System.out.println(elt);}// 2，迭代器for(Iterator<String> iter = set.iterator(); iter.hasNext() ; ){String elt = iter.next();System.out.println(elt);}}

遍历map

public static void main(String[] args) {// 遍历Map：Map<String, String> map = new HashMap<String, String>();map.put("aa", "xx");map.put("bb", "yy");map.put("cc", "zz");// 1，增强的for循环（Entry集合）for (Entry<String, String> entry : map.entrySet()) {System.out.println(entry);}// 2，增强的for循环（Key集合）for(String key : map.keySet()){System.out.println(key + " = " + map.get(key));}// 3，遍历值的集合for(String value : map.values()){System.out.println(value);}}

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