Java HashMap content to String [duplicate]

Question

Please read comments before You downmark!

I want convert content of HashMap to String as converting ArrayList to String using Arrays.toString(arrayList).

Is it possible ? There is easy way to do this?

Do I must have to iteration and appending it using Iterator ? As example:

HashMap<String, ArrayList<MyObject>> objectMap = new HashMap<String, ArrayList<>>();

//.... put many items to objectMap

Iterator it = objectMap.entrySet().iterator();

while(it.hasNext()){
  Map.Entry pairs = (Map.Entry) it.next();
  System.out.println(pairs.getKey() + " = " + pairs.getValue());
}

I think that it is different because of pair <String, ArrayList> not <String, Integer>

Bahramdun Adil · Accepted Answer · 2016-02-24 08:27:40Z

10

You can use toString() of the Map:

String content = objectMap.toString();

Map overrides the toString() method, so you can easily get the contents of map.

I should give an example:

public static void main(String[] args) throws Exception {
    HashMap<String, List<MyObject>> objectMap = new HashMap<>();
    List<MyObject> list = new ArrayList<>();
    list.add(new MyObject(12, 12));
    objectMap.put("aaaa", list);
    String content = objectMap.toString();
    System.out.println("content = " + content);
}

private static class MyObject {
    int min;
    int max;

    public MyObject(int max, int min) {
        this.max = max;
        this.min = min;
    }

    @Override
    public String toString() {
        return "MyObject{" +
                "max=" + max +
                ", min=" + min +
                '}';
    }
}

And it is the output:

content = {aaaa=[MyObject{max=12, min=12}]}

So it means it works well

edited Feb 24, 2016 at 8:27

answered Feb 24, 2016 at 8:13

Bahramdun Adil

6,0878 gold badges38 silver badges72 bronze badges

Sign up to request clarification or add additional context in comments.

19 Comments

CeZet Over a year ago

Nope, it don't work.

Bahramdun Adil Over a year ago

What is the reason of don't work?

CeZet Over a year ago

It return bad String, not content but strange String about package where it from.

Prashant Over a year ago

This is the reason: public final String toString() { return key + "=" + value; }. If value is an object, its toString() is not called

Bahramdun Adil Over a year ago

No, this problem is not belongs to Serializable

|

Collectives™ on Stack Overflow

Java HashMap content to String [duplicate]

1 Answer 1

19 Comments

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

19 Comments

Linked

Related