HashMap的几种遍历方式案列

假设有一个HashMap<Integer, String> map，以下是几种遍历方式的示例代码：

1. 使用for-each循环遍历key

for(Integer key : map.keySet()) {
    System.out.println("Key: " + key);
}

2. 使用for-each循环遍历value

for(String value : map.values()) {
    System.out.println("Value: " + value);
}

3. 使用for-each循环遍历entry

for(Map.Entry<Integer, String> entry : map.entrySet()) {
    Integer key = entry.getKey();
    String value = entry.getValue();
    System.out.println("Key: " + key + ", Value: " + value);
}

4. 使用Iterator遍历key

Iterator<Integer> iterator = map.keySet().iterator();
while(iterator.hasNext()) {
    Integer key = iterator.next();
    System.out.println("Key: " + key);
}

5. 使用Iterator遍历value

Iterator<String> iterator = map.values().iterator();
while(iterator.hasNext()) {
    String value = iterator.next();
    System.out.println("Value: " + value);
}

6. 使用Iterator遍历entry

Iterator<Map.Entry<Integer, String>> iterator = map.entrySet().iterator();
while(iterator.hasNext()) {
    Map.Entry<Integer, String> entry = iterator.next();
    Integer key = entry.getKey();
    String value = entry.getValue();
    System.out.println("Key: " + key + ", Value: " + value);
}