Summary of several looping ways of Java Map

According to the JDK's new features, a For loop Map, such as a loop Map Key, is used

Java code

for(String dataKey : paraMap.keySet())    
{    
    System.out.println(dataKey );               
} 

Notice how paraMap is defined, if it's a simple Map paraMap = new HashMap(); Then the String in front of it can only be changed to Object.

The key and value of the entire Map are looped as follows:

Java code

for(Map.Entry<String, Object> entry : paraMap.entrySet())    
{    
    System.out.println(entry.getKey()+": "+entry.getValue());    
} 

In the old days, it would have been like this:

Java code

Iterator it = paraMap.entrySet().iterator();    
while (it.hasNext())     
{    
        Map.Entry pairs = (Map.Entry)it.next();    
        System.out.println(pairs.getKey() + " = " + pairs.getValue());    
 }