Android - Get value from HashMap
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?
Solution 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();
}
Solution 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
.
- If you want to modify the map while iterating, you'd need to use its
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?