Add Strings to Map

Question

I have two String arrays of the same size.

I need to make a Map with name and value. How do I add them to the Map?

String[] labelNames = request.getParameterValues("labelName");
String[] labelValues = request.getParameterValues("labelValues");
Map<String,String> labels = new HashMap<>();

What do you want to have happen if the `labelName` and `labelValues` arrays are not the same length? — Daniel Pryden, Jan 25 '18 at 12:56

score 2 · Answer 1 · answered Jan 25 '18 at 12:51

2

You have arrays of same size, so you can iterate over them with the same for-loop, you'll access same index on both and put them into the map :

for(int i=0; i<labelNames.length; i++){
    labels.put(labelNames[i], labelValues [i]);
}

answered Jan 25 '18 at 12:51

azro

53,056
7
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CodeMatrix · Answer 2 · 2018-01-25T12:57:33.873

2

If you got 2 arrays where the size is the same just make a for-loop which uses the labelName and the labelValue

for(int i = 0; i < labelNames.length; i++) {
    labels.put(labelNames[i], labelValues[i]);
}

if you're not sure if the size of the two arrays is the same add this check before the loop:

if(labelNames.length == labelValues.length) {...}

edited Jan 25 '18 at 12:57

answered Jan 25 '18 at 12:52

CodeMatrix

2,124
1
18
30

score 1 · Answer 3 · edited Jul 07 '20 at 17:02

A solution for Java 7 - you can use the for loop structure with a single index to advance into the 2 arrays at the same time.

As for the assumption labelNames.length == labelValues.length it is usually better to always check it to make sure you didn't introduce a bug and get unexpected results:

if(labelNames.length == labelValues.length) {
    int i;
    for(i = 0; i < labelNames.length; i++) {
        labels.put(labelNames[i], labelValues[i]);
    }
}

In Java 8 you could use Streams as an alternative:

Map<String, String> map =
        IntStream.range(0, names.length)
                .boxed()
                .collect(Collectors.toMap(i -> labelNames[i], i -> labelValues[i]));

score 1 · Answer 4 · answered Jan 25 '18 at 12:52

1

use this code :

Map<String,String> labels = new HashMap<>();
for(int i=0;i<labelNames.length;i++)
    labels.put(labelNames[i] , labelValues[i]);

answered Jan 25 '18 at 12:52

Ali Faris

17,754
10
45
70

score 1 · Answer 5 · answered Jan 25 '18 at 12:54

1

First of all:

 Map<String,String> labels = new HashMap<String, String>();

and then:

for (int i=0; i < labelNames.length; i++) 
{
  labels.put(labelNames[i], labelValues[i]);
}

answered Jan 25 '18 at 12:54

Flocke

764
6
14

1

There is already 5 times this answer, no need to spam – azro Jan 25 '18 at 12:54
It takes a minute or two to write an answer. In the meantime other users may publish solutions. – Flocke Jan 25 '18 at 13:50

Add Strings to Map

5 Answers5