Android - Get value from HashMap

Question

I have tried to search on HashMap in Android, but getting problem:

Consider this example:

HashMap<String, String> meMap=new HashMap<String, String>();
meMap.put("Color1","Red");
meMap.put("Color2","Blue");
meMap.put("Color3","Green");
meMap.put("Color4","White");

now I want to iterate it and get the value of each color and want to display in "Toast". how do I display it?

Falcate

developer.android.com/reference/java/util/HashMap.html – Albuminuria

@Albuminuria ya i have already seen android-sdk – Falcate

Maybe you should also read the available methods like keySet(), not just the descriptions. – Superhuman

@Superhuman Dont know anything about HashMap....so by theory how can i come to know....btw thanx for help and support – Falcate

The SDK contains descriptions about the methods it has, you should check and see what kind of methods can be run on HashMap prior to asking. – Superhuman

Answer 1

Iterator myVeryOwnIterator = meMap.keySet().iterator();
while(myVeryOwnIterator.hasNext()) {
    String key=(String)myVeryOwnIterator.next();
    String value=(String)meMap.get(key);
    Toast.makeText(ctx, "Key: "+key+" Value: "+value, Toast.LENGTH_LONG).show();
}

Superhuman

Note that iteration order is undefined. If you want the same order as the sets were added use LinkedHashMap – Pocked

the above code is iterated over only on "key"..but not for "Value"..such as it displays only "color1", "color2"...etc. instead of "red", "blue", etc. – Falcate

Just make a request to hashmap for the key and you will have it, I updated my code. – Superhuman

how to add LinkedHashMap to return in same order, help please. – Pertinacious

Answer 2

Here's a simple example to demonstrate Map usage:

Map<String, String> map = new HashMap<String, String>();
map.put("Color1","Red");
map.put("Color2","Blue");
map.put("Color3","Green");
map.put("Color4","White");

System.out.println(map);
// {Color4=White, Color3=Green, Color1=Red, Color2=Blue}        

System.out.println(map.get("Color2")); // Blue

System.out.println(map.keySet());
// [Color4, Color3, Color1, Color2]

for (Map.Entry<String,String> entry : map.entrySet()) {
    System.out.printf("%s -> %s%n", entry.getKey(), entry.getValue());
}
// Color4 -> White
// Color3 -> Green
// Color1 -> Red
// Color2 -> Blue

Note that the entries are iterated in arbitrary order. If you need a specific order, then you may consider e.g. LinkedHashMap

See also

• Effective Java 2nd Edition, Item 52: Refer to objects by their interfaces
• Java Tutorials/Collections - The Map interface
• Java Language Guide/The for-each loop

Related questions

On iterating over entries:

• Iterate Over Map
• iterating over and removing from a map
  • If you want to modify the map while iterating, you'd need to use its Iterator.

On different Map characteristics:

• How to Maintain order of insertion using collections

---

On enum

You may want to consider using an enum and EnumMap instead of Map<String,String>.

See also

• Java Language Guide/Enums

Related questions

• Enumerations: Why? When?

Fortitude

import java.util.*; must be added – Bambi

If you only want the values, this answer is clearly more understandable – Olomouc

Answer 3

This with no warnings!

    HashMap<String, String> meMap=new HashMap<String, String>();
    meMap.put("Color1","Red");
    meMap.put("Color2","Blue");
    meMap.put("Color3","Green");
    meMap.put("Color4","White");

    for (Object o : meMap.keySet()) {
        Toast.makeText(getBaseContext(), meMap.get(o.toString()),
                Toast.LENGTH_SHORT).show();
    }

Capitalism

Answer 4

HashMap<String, String> meMap = new HashMap<String, String>();
meMap.put("Color1", "Red");
meMap.put("Color2", "Blue");
meMap.put("Color3", "Green");
meMap.put("Color4", "White");

Iterator myVeryOwnIterator = meMap.values().iterator();
while(myVeryOwnIterator.hasNext()) {
    Toast.makeText(getBaseContext(), myVeryOwnIterator.next(), Toast.LENGTH_SHORT).show();
}

Anselmi

Answer 5

for (Object key : meMap.keySet()) {
        String value=(String)meMap.get(key);
        Toast.makeText(ctx, "Key: "+key+" Value: "+value, Toast.LENGTH_LONG).show();
    }

Sorcery

Answer 6

HashMap<String, String> meMap=new HashMap<String, String>();
meMap.put("Color1","Red");
meMap.put("Color2","Blue");
meMap.put("Color3","Green");
meMap.put("Color4","White");
Iterator iterator = meMap.keySet().iterator();
while( iterator. hasNext() ){
    Toast.makeText(getBaseContext(), meMap.get(iterator.next().toString()), 
    Toast.LENGTH_SHORT).show();
}

Damien

Answer 7

this work for me:

HashMap<String, String> meMap=new HashMap<String, String>();
meMap.put("Color1","Red");
meMap.put("Color2","Blue");
meMap.put("Color3","Green");
meMap.put("Color4","White");

Iterator iterator = meMap.keySet().iterator();
while( iterator. hasNext() )
{
    Toast.makeText(getBaseContext(), meMap.get(iterator.next().toString()), 
    Toast.LENGTH_SHORT).show();
}

Araxes

Answer 8

Note: If you know Key, use this code

String value=meMap.get(key);

Hedonic

Answer 9

 Iterator iterator = meMap.keySet().iterator();
                while(iterator.hasNext() ){
                  //get key
                    String key=(String)iterator.next();
                    //toast value
                                           Toast.makeText(getBaseContext(),""+(String)meMap.get(key),Toast.LENGTH_SHORT).show();

                }

Subternatural

Answer 10

Below code will generate unique random numbers list.

int size = 10; // Change according to your need
List<Integer> Lucky = new ArrayList<>();
while(Lucky.size()<size)
{
int r = new Random().nextInt(1000); 
if(!Lucky.contains(r)) Lucky.add(r); 
}

Speedwell