Map, how to print both the "key string" and "value string" together

Question

I'm new to Java and is trying to learn the concept of Maps.

I have came up with the code below. However, I want to print out the "key String" and "value String" at the same time.

ProcessBuilder pb1 = new ProcessBuilder();
Map<String, String> mss1 = pb1.environment();
System.out.println(mss1.size());

for (String key: mss1.keySet()){
    System.out.println(key);
}

I could only find method that print only the "key String".

One liner with apache.commons.lang.StringUtils: `String message = StringUtils.join(yourMap.entrySet().toArray(), "\n");` — Noam Manos, Nov 06 '17 at 07:55

score 36 · Accepted Answer · answered Feb 26 '16 at 03:02

There are various ways to achieve this. Here are three.

    Map<String, String> map = new HashMap<String, String>();
    map.put("key1", "value1");
    map.put("key2", "value2");
    map.put("key3", "value3");

    System.out.println("using entrySet and toString");
    for (Entry<String, String> entry : map.entrySet()) {
        System.out.println(entry);
    }
    System.out.println();

    System.out.println("using entrySet and manual string creation");
    for (Entry<String, String> entry : map.entrySet()) {
        System.out.println(entry.getKey() + "=" + entry.getValue());
    }
    System.out.println();

    System.out.println("using keySet");
    for (String key : map.keySet()) {
        System.out.println(key + "=" + map.get(key));
    }
    System.out.println();

Output

using entrySet and toString
key1=value1
key2=value2
key3=value3

using entrySet and manual string creation
key1=value1
key2=value2
key3=value3

using keySet
key1=value1
key2=value2
key3=value3

Use Map.Entry instead of Entry – shyam Aug 05 '19 at 16:12 — shyam, Aug 05 '19 at 16:12

score 5 · Answer 2 · answered Feb 26 '16 at 02:52

5

Inside of your loop, you have the key, which you can use to retrieve the value from the Map:

for (String key: mss1.keySet()) {
    System.out.println(key + ": " + mss1.get(key));
}

answered Feb 26 '16 at 02:52

blacktide

8,986
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score 5 · Answer 3 · answered Feb 26 '16 at 03:01

final Map<String, String> mss1 = new ProcessBuilder().environment();
mss1.entrySet()
        .stream()
        //depending on how you want to join K and V use different delimiter
        .map(entry -> 
        String.join(":", entry.getKey(),entry.getValue()))
        .forEach(System.out::println);

Map, how to print both the "key string" and "value string" together

3 Answers3

Output

Linked