how to get values from hashmap using loop

Question

How can i print all the values from the following hashmap

ServletContext appScope = request.getServletContext();
        Map<String, List<String>> onLine = (HashMap<String, List<String>>)appScope.getAttribute("User");
        if(onLine != null) {
            out.print(onLine.get("1"));
        }

score 2 · Accepted Answer · answered Feb 18 '14 at 14:12

2

if (onLine != null) {
    for (String k : onLine.keySet()) {
        for (String v : onLine.get(k)) {
            out.print(v);
        }
    }
}

answered Feb 18 '14 at 14:12

Marco Bolis

1,222
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score 2 · Answer 2 · answered Feb 18 '14 at 14:21

2

java.util.Map has a values() method just for this:

for(List<String> nextArray : onLine.values()) {
    for(String nextString : nextArray) {
        out.print(nextString);
    }
}

answered Feb 18 '14 at 14:21

Peter Bratton

6,302
6
39
61

score 1 · Answer 3 · answered Feb 18 '14 at 14:17

1

Try this:

if (onLine != null) {
    for (String key : onLine.keySet()) {
        for (List<String> val : onLine.get(key)) {
            for(String str : val){
                System.out.print(str);
            }
        }
    }
}

This will print all the strings in your map.

answered Feb 18 '14 at 14:17

davioooh

23,742
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250

this answer is actually wrong – Marco Bolis Feb 18 '14 at 14:35

score 1 · Answer 4 · answered Feb 18 '14 at 14:24

1

if you need both key and values:

for( Map.Entry<String, List<String>> e : yourMap.entrySet() )
  System.out.println( "key=" + e.key() + ", value=" + e.value() );

answered Feb 18 '14 at 14:24

injecteer

20,038
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89

score 1 · Answer 5 · edited Feb 18 '14 at 15:24

I wrote a demo, you can try it

public static void main(String[] args) {

         Map<String, Integer> map = new HashMap<String, Integer>();
         map.put("k1", 1);
         map.put("k2", 2);
         map.put("k3", 3);
         map.put("k4", 4);
         map.put("k5", 5);

         Set<String> keys = map.keySet();
         for(String key:keys) {
            System.out.println("key:" + key);
            System.out.println("value:" + map.get(key));
         }
}

how to get values from hashmap using loop

5 Answers5