How to print all key and values from HashMap in Android?

Question

I am trying to use HashMap in Android sample project. Now, am doing sample project for learn android. I just store keys and values in HashMap, i want to show the keys and their values in EditView. I followed below code in my sample project. But, first key and value only printing in EditView.

   Map<String, String> map = new HashMap<String,String>();
   map.put("iOS", "100");
   map.put("Android", "101");
   map.put("Java", "102");
   map.put(".Net", "103");
   
   Set keys = map.keySet();

   for (Iterator i = keys.iterator(); i.hasNext(); ) {
       String key = (String) i.next();
       String value = (String) map.get(key);
       textview.setText(key + " = " + value);
   }

In EditView iOS = 100 is only printing. I want to print all keys and their value in EditText. What am I doing wrong?

See this question and many others: http://stackoverflow.com/questions/1066589/java-iterate-through-hashmap — Anton, Jan 18 '12 at 12:09
hello Gopinath !! Your code to fetch and set the Hash map key value is correct but you are setting these value to only one textView . — deepak Sharma, Jan 18 '12 at 12:10
Thanks to all. I got the answer. Once again i thank you all. — Gopinath, Jan 18 '12 at 12:22

score 191 · Answer 1 · answered Jan 18 '12 at 12:10

191

for (Map.Entry<String,String> entry : map.entrySet()) {
  String key = entry.getKey();
  String value = entry.getValue();
  // do stuff
}

answered Jan 18 '12 at 12:10

Shadow

6,161
3
20
14

score 13 · Answer 2 · answered May 08 '17 at 08:50

13

You can do it easier with Gson:

Log.i(TAG, "SomeText: " + new Gson().toJson(yourMap));

The result will look like:

I/YOURTAG: SomeText: {"key1":"value1","key2":"value2"}

answered May 08 '17 at 08:50

Anh Vu

219
3
10

Helpful. Thanks a lot. – Pooja Aug 19 '20 at 18:49

score 12 · Answer 3 · answered Jan 18 '12 at 12:16

It's because your TextView recieve new text on every iteration and previuos value thrown away. Concatenate strings by StringBuilder and set TextView value after loop. Also you can use this type of loop:

for (Map.Entry<String, String> e : map.entrySet()) {
    //to get key
    e.getKey();
    //and to get value
    e.getValue();
}

Abhi · Answer 4 · 2014-05-29T11:16:24.790

11

HashMap <Integer,Integer> hm = new HashMap<Integer,Integer>();

Set<Integer> keys = hm.keySet();  //get all keys
for(Integer i: keys)
{
    System.out.println(hm.get(i));
}

edited May 29 '14 at 11:16

answered May 28 '14 at 20:34

Abhi

119
1
3

Doesn't address the actual problem with the OP's code, which is almost identical. – user207421 Mar 31 '20 at 04:07

score 11 · Accepted Answer · edited Jul 20 '17 at 20:28

11

First, there are errors in your code, ie. you are missing a semicolon and a closing parenthesis in the for loop.

Then, if you are trying to append values to the view, you should use textview.appendText(), instead of .setText().

There's a similar question here: how to change text in Android TextView

edited Jul 20 '17 at 20:28

Gary

13,303
18
49
71

answered Jan 18 '12 at 12:09

Savino Sguera

3,522
21
20

2

This is the best answer, but see also @Shadow for how to use Java 5 for and Map.Entry properly. – Dean Povey Jan 18 '12 at 12:12

mdev · Answer 6 · 2020-03-31T03:35:15.070

5

With Java 8:

map.keySet().forEach(key -> System.out.println(key + "->" + map.get(key)));

edited Mar 31 '20 at 03:35

answered Nov 02 '16 at 22:51

mdev

1,366
17
23

1

Could you please [edit] in an explanation of why this code answers the question? Code-only answers are [discouraged](http://meta.stackexchange.com/q/148272/274165), because they don't teach the solution. – Nathan Tuggy Nov 02 '16 at 23:25
OP wants to print all keys and value pairs. I dont think any explanation is needed here. It is an very old thread, already answered, and also no brain thing. I have already written if someone is looking for a solution in Java8, he/she can do something like that. – mdev Nov 04 '16 at 01:37
1

mdev - There are many newbies here who would benefit from an explanation, even if it is obvious to an expert like you. If you would have provided an explanation, you might have discovered that your solution is incorrect; (teh "result" variable is unspecified). It should be: map.keySet().forEach(key -> System.out.println(key + "->" + map.get(key))); Where the -> separates the parameters (left-side) from the implementation (right side). See https://howtodoinjava.com/java8/foreach-method-example/ and https://docs.oracle.com/javase/tutorial/java/javaOO/lambdaexpressions.html – Tihamer Mar 30 '20 at 18:36
Tihamer Thanks for pointing the typo. I have edited the answer. – mdev Mar 31 '20 at 03:36
The OP wants to *display* all the keys and values in a text field, and his only problem is in that part of it. – user207421 Mar 31 '20 at 04:08

score 5 · Answer 7 · answered Apr 24 '17 at 13:52

5

Java 8

map.entrySet().forEach(System.out::println);

answered Apr 24 '17 at 13:52

bluehallu

10,205
9
44
61

score 4 · Answer 8 · answered May 18 '18 at 04:35

4

    for (String entry : map.keySet()) {
      String value = map.get(entry);
      System.out.print(entry + "" + value + " ");
      // do stuff
    }

answered May 18 '18 at 04:35

Sundresh

185
5

score 2 · Answer 9 · answered Jan 18 '12 at 12:10

2

String text="";

    for (Iterator i = keys.iterator(); i.hasNext() 
       {
           String key = (String) i.next();
           String value = (String) map.get(key);
           text+=key + " = " + value;
       }

        textview.setText(text);

answered Jan 18 '12 at 12:10

jeet

29,001
6
52
53

score 1 · Answer 10 · answered Jun 14 '12 at 21:16

This code is tested and working.

public void dumpMe(Map m) { dumpMe(m, ""); }
private void dumpMe(Map m, String padding) {
  Set s = m.keySet();
  java.util.Iterator ir = s.iterator();
  while (ir.hasNext()) {
    String key = (String) ir.next();
    Object value = m.get(key);
    if (value == null) continue;
    if (value instanceof Map) {
      System.out.println (padding + key + " = {");
      dumpMe((Map)value, padding + "  ");
      System.out.println(padding + "}");          
    }
    else if (value instanceof String  ||
             value instanceof Integer ||
             value instanceof Double  ||
             value instanceof Float   ||
             value instanceof Long ) {

      System.out.println(padding + key + " = " + value.toString());
    }
    else { 
      System.out.println(padding + key + " = UNKNOWN OBJECT: " + value.toString());
      // You could also throw an exception here
    }      
  } // while

} // dumpme

Charles.

Thank you, added this to my utils – moberme Apr 11 '14 at 23:20 — moberme, Apr 11 '14 at 23:20

score 1 · Answer 11 · answered Jul 23 '21 at 19:16

1

To print all keys:

myMap.keys().toList().joinToString()

To print all entries:

myMap.map { "${it.key} :: ${it.value}" }.toList().joinToString()

answered Jul 23 '21 at 19:16

Alécio Carvalho

13,481
5
68
74

score 0 · Answer 12 · answered May 11 '14 at 04:55

you can use this code:

for (Object variableName: mapName.keySet()){
    variableKey += variableName + "\n";
    variableValue += mapName.get(variableName) + "\n";
}
System.out.println(variableKey + variableValue);

this code will make sure that all the keys are stored in a variable and then printed!

Deepak Daniel · Answer 13 · 2016-09-03T05:36:28.517

public void dumpMe(Map m) { dumpMe(m, ""); }

private void dumpMe(Map m, String padding) 
{
    Set s = m.keySet();
    java.util.Iterator ir = s.iterator();
    while (ir.hasNext()) 
    {
        String key = (String) ir.next();
        AttributeValue value = (AttributeValue)m.get(key);
        if (value == null) 
            continue;
        if (value.getM() != null)
        {
            System.out.println (padding + key + " = {");
            dumpMe((Map)value, padding + "  ");
            System.out.println(padding + "}");          
        }
        else if (value.getS() != null  ||
                 value.getN() != null ) 
        {
            System.out.println(padding + key + " = " + value.toString());
        }
        else 
        { 
            System.out.println(padding + key + " = UNKNOWN OBJECT: " + value.toString());
            // You could also throw an exception here
        }      
    } // while
}

//This code worked for me.

1

Please look at [answer] – JimHawkins Sep 03 '16 at 05:34

score -1 · Answer 14 · answered Mar 07 '18 at 04:41

For everyone who clicked on this to find out what the content of your HashMap is, the toString method (docs) actually works with most objects. (note: a java array is not an object!)

So this woks perfectly fine for debugging purposes:

System.out.println(myMap.toString());

>>> {key1=value1, key2=value2}

score -1 · Answer 15 · answered Jan 13 '20 at 19:25

Kotlin Answer

for ((key, value) in map.entries) {
    // do something with `key`
    // so something with `value`
}

You may find other solutions that include filterValues. Just keep in mind that retrieving a Key value using filterValues will include braces [].

val key = map.filterValues {it = position}.keys

How to print all key and values from HashMap in Android?

15 Answers15

Linked