java hashmap key iteration
Solution 1
With for-each loop, use Map.keySet()
for iterating keys, Map.values()
for iterating values and Map.entrySet()
for iterating key/value pairs.
Note that all these are direct views to the map that was used to acquire them so any modification you make to any of the three or the map itself will reflect to all the others too.
Solution 2
Yes, you do this by getting the entrySet()
of the map. For example:
Map<String, Object> map = new HashMap<String, Object>();
// ...
for (Map.Entry<String, Object> entry : map.entrySet()) {
System.out.println("key=" + entry.getKey() + ", value=" + entry.getValue());
}
(Ofcourse, replace String
and Object
with the types that your particular Map
has - the code above is just an example).
Solution 3
public class abcd {
public static void main(String[] args)
{
Map<Integer, String> testMap = new HashMap<Integer, String>();
testMap.put(10, "a");
testMap.put(20, "b");
testMap.put(30, "c");
testMap.put(40, "d");
for (Entry<Integer, String> entry : testMap.entrySet()) {
Integer key=entry.getKey();
String value=entry.getValue();
}
}
}
Solution 4
for (Map.Entry<T,U> e : map.entrySet())
{
T key = e.getKey();
U value = e.getValue();
.
.
.
}
In addition, if you use a LinkedHashMap as the implementation, you'll iterate in the order the key/value pairs were inserted. If that's not important, use a HashMap.
Solution 5
hashmap.keySet().iterator()
use a for
loop to iterate it.
then use hashmap.get(item)
to get individual values,
Alternatively just use entrySet()
for getting an iterator for values.
ping
Im a java Developer, fresh out of college, still in the process of finding my feet
Updated on July 09, 2022Comments
-
ping almost 2 years
Is there any way to iterate through a java Hashmap and print out all the values for every key that is a part of the Hashmap?