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default void forEach(BiConsumer<? super K, ? super V> action) {
Objects.requireNonNull(action);
for (Map.Entry<K, V> entry : entrySet()) {
K k;
V v;
try {
k = entry.getKey();
v = entry.getValue();
} catch(IllegalStateException ise) {
// this usually means the entry is no longer in the map.
throw new ConcurrentModificationException(ise);
}
action.accept(k, v);
}
}

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/**
* Performs the given action for each entry in this map until all entries
* have been processed or the action throws an exception.
Unless
* otherwise specified by the implementing class, actions are performed in
* the order of entry set iteration (if an iteration order is specified.)
* Exceptions thrown by the action are relayed to the caller.
*
* @implSpec
* The default implementation is equivalent to, for this {@code map}:
* <pre> {@code
* for (Map.Entry<K, V> entry : map.entrySet())
*
action.accept(entry.getKey(), entry.getValue());
* }</pre>
*
* The default implementation makes no guarantees about synchronization
* or atomicity properties of this method. Any implementation providing
* atomicity guarantees must override this method and document its
* concurrency properties.
*
* @param action The action to be performed for each entry
* @throws NullPointerException if the specified action is null
* @throws ConcurrentModificationException if an entry is found to be
* removed during iteration
* @since 1.8
*/

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对该映射中的每个条目执行给定的操作，直到处理完所有条目或该操作引发异常为止。除非实现类另有指定，否则操作将按条目集迭代的顺序执行（如果指定了迭代顺序）。操作引发的异常将转发给调用方。
*
*@implSpec公司
*对于这个{@code map}，默认实现相当于：
*<pre>{@代码
*for（Map.Entry<K，V>Entry:Map.entrySet（））
*action.accept（entry.getKey（），entry.getValue（））；
*}</pre>
*
*默认实现不保证此方法的同步性或原子性属性。任何提供原子性保证的实现都必须重写此方法并记录其并发属性。
*
*@param action为每个条目执行的操作
*如果指定的操作为null，@throws NullPointerException
*如果在迭代过程中发现某个条目被删除，@抛出ConcurrentModificationException
*@自1.8

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package test_0;
import java.util.HashMap;
import java.util.Map;
/**
* @className: Map_1_8.java
* @description: TODO map在JDK1.8之后与之前的不同应用
* @author: LiXiangyu
* @date: 2021年7月23日
**/
public class Map_1_8 {
public static void main(String[] args) {
// TODO Auto-generated method stub
Map<Object, Object> map = new HashMap<>();
map.put("name", "sun");
map.put("phone", "18888888888");
map.put(null, null);
// 通用的Map迭代方式
System.out.println("==============Map的通用迭代======================");
for (Map.Entry<Object, Object> entry : map.entrySet()) {
System.out.println(entry.getKey() + "：" + entry.getValue());
}
System.out.println("==============Map的1.8迭代=====================");
Map<Object, Object> map8 = new HashMap<>();
map8.put(null, null);
map8.put("phone", "16666688888");
map8.put("sex", "男");
map8.put("name", "li");
// JDK8的迭代方式
map8.forEach((key, value) -> {
System.out.println(key + "：" + value);
});
}
}