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【Java基础】Map遍历的5种方式

news 2025/8/3 0:30:53

创建一个集合

    HashMap<Integer, String> map = new HashMap<>();map.put(1,"ljj");map.put(2,"zsy");map.put(3,"sxf");map.put(4,"wjx");}

方式一：Iterator 迭代器遍历

map.entrySet().iterator();

map.keySet().iterator();

//Iterator 迭代器遍历public static void iterator(Map<Integer, String> map){System.out.println("---使用entrySet()迭代器进行遍历map集合---");Iterator<Map.Entry<Integer, String>> entryIterator = map.entrySet().iterator();while (entryIterator.hasNext()){Map.Entry<Integer, String> entry = entryIterator.next();System.out.println(entry.getKey()+":"+entry.getValue());}System.out.println("---使用KeySet()迭代器进行遍历map集合---");Iterator<Integer> keySetIterator = map.keySet().iterator();while (keySetIterator.hasNext()){Integer key = keySetIterator.next();System.out.println(key+":"+map.get(key));}}

方式二：For Each方式遍历

map.forEach(BiConsumer action)

 //For Each方式遍历public static void forEach_map(Map<Integer,String> map){System.out.println("map.forEach(BiConsumer action)方法遍历map");map.forEach((key,value) -> System.out.println(key+" : "+value));}

方式三：获取Collection集合

map.values().forEach()

map中的values()方法，通过这个方法可以直接获取Map中存储所有值的Collection集合

 //values()方法public static void Collection_forEach(Map<Integer,String> map){System.out.println("获取map集合的values值集合对象，进行forEach遍历");//Map中的values()方法，通过这个方法可以直接获取Map中存储所有值的Collection集合Collection<String> values = map.values();values.forEach( v -> System.out.println(v));}

方式四：增强for遍历map

map.entrySet().for

map.keySet().for

    public static void for_plus(Map<Integer,String> map){System.out.println("增强for循环，Map.Entry<>");for (Map.Entry<Integer,String> entry : map.entrySet()){String value = entry.getValue();System.out.println(value);}System.out.println("增强for循环，map.keySet");for (Integer key : map.keySet()){String value = map.get(key);System.out.println(value);}}

方法五：Stream流遍历

map.entrySet().stream().forEach()

map.keySet().stream().forEach()

//Stream流遍历public static void stream_list(Map<Integer,String> map){System.out.println("map.entrySet().stream.forEach()遍历—Stream流遍历");map.entrySet().stream().forEach((Map.Entry<Integer,String> entry) -> {System.out.print(entry.getKey()+":");System.out.println(entry.getValue());});System.out.println("map.keySet().stream.forEach()遍历—Stream流遍历");map.keySet().stream().forEach(key -> {System.out.println(map.get(key));});}