Android - Get value from HashMap

Question

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

Consider this example:

HashMap meMap=new HashMap

        

Answer 1

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();
    }

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?

Answer 3

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();
}