CODEWITHSUNDEEP
javafor-loophashmap
Tim R
Tim R

Reputation: 524

Alternate for loop with hasmap in java

I have a for each loop running as:

for (System system : val.keySet()) 
{
   do something
}

Is there an alternate method to write this?

Upvotes: 0

Views: 213

Answers (1)

Mohammed Aouf Zouag
Mohammed Aouf Zouag

Reputation: 17142

Here are some ways how you can loop through a map:

1- Using for-Each loop:

Map<Integer, Integer> map = new HashMap<Integer, Integer>();
for (Map.Entry<Integer, Integer> entry : map.entrySet()) {
    System.out.println("Key = " + entry.getKey() + ", Value = " + entry.getValue());
}

2- Iterating over keys or values

Map<Integer, Integer> map = new HashMap<Integer, Integer>();

//iterating over keys only
for (Integer key : map.keySet()) {
    System.out.println("Key = " + key);
}

//iterating over values only
for (Integer value : map.values()) {
    System.out.println("Value = " + value);
}

3- Using iterator:

Map<Integer, Integer> map = new HashMap<Integer, Integer>(); 
Iterator<Map.Entry<Integer, Integer>> entries = map.entrySet().iterator(); 

while (entries.hasNext()) {
    Map.Entry<Integer, Integer> entry = entries.next();
    System.out.println("Key = " + entry.getKey() + ", Value = " + entry.getValue()); 
}

Upvotes: 2

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