Methods for looping map and obtaining map values in java

Cyclic traversal of map

The code is as follows:

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Package com. sec. map;     Import java. util. HashMap; Import java. util. Iterator; Import java. util. Map;     Public class TestMap {     Public static void main (String [] args ){         Map <String, String> map = new HashMap <String, String> ();   Map. put ("1", "value1 ");   Map. put ("2", "value2 ");   Map. put ("3", "value3 ");                 // The first type is commonly used. The second value is used.   System. out. println ("traverse key and value through Map. keySet :");   For (String key: map. keySet ()){   System. out. println ("key =" + key + "and value =" + map. get (key ));             }   System. out. println ("www.111cn.net ");   // Type 2   System. out. println ("traverse key and value through Map. entrySet using iterator :");   Iterator <Map. Entry <String, String> it = map. entrySet (). iterator ();   While (it. hasNext ()){   Map. Entry <String, String> entry = it. next ();   System. out. println ("key =" + entry. getKey () + "and value =" + entry. getValue ());             }   System. out. println ("www.111cn.net ");   // Method 3: recommended, especially when the capacity is large   System. out. println ("traversing key and value through Map. entrySet ");   For (Map. Entry <String, String> entry: map. entrySet ()){   System. out. println ("key =" + entry. getKey () + "and value =" + entry. getValue ());             }   System. out. println ("www.111cn.net ");   // Category 4   System. out. println ("traverse all values through Map. values (), but not key ");   For (String v: map. values ()){   System. out. println ("value =" + v );             }   System. out. println ("www.111cn.net ");          }   }

Supplement:

First, use the for loop
Java code

The code is as follows:	Copy code
For (Map. Entry <String, String> entry: map. entrySet ()){ System. out. println (entry. getKey () + "--->" + entry. getValue ()); }   For (Map. Entry <String, String> entry: map. entrySet ()){ System. out. println (entry. getKey () + "--->" + entry. getValue ()); }

Second, iteration
Java code

The code is as follows:

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Set set = map. entrySet (); Iterator I = set. iterator (); While (I. hasNext ()){ Map. Entry <String, String> entry1 = (Map. Entry <String, String>) I. next (); System. out. println (entry1.getKey () + "=" + entry1.getValue ()); }   Set set = map. entrySet (); Iterator I = set. iterator (); While (I. hasNext ()){ Map. Entry <String, String> entry1 = (Map. Entry <String, String>) I. next (); System. out. println (entry1.getKey () + "=" + entry1.getValue ()); }

Use keySet () for iteration
Java code

The code is as follows:	Copy code
Iterator it = map. keySet (). iterator (); While (it. hasNext ()){ String key; String value; Key = it. next (). toString (); Value = map. get (key ); System. out. println (key + "--" + value ); }   Iterator it = map. keySet (). iterator (); While (it. hasNext ()){ String key; String value; Key = it. next (). toString (); Value = map. get (key ); System. out. println (key + "--" + value ); }

Use entrySet () for iteration
Java code

The code is as follows:	Copy code
Iterator it = map. entrySet (). iterator (); System. out. println (map. entrySet (). size ()); String key; String value; While (it. hasNext ()){ Map. Entry entry = (Map. Entry) it. next (); Key = entry. getKey (). toString (); Value = entry. getValue (). toString (); System. out. println (key + "=" + value ); }