Which collection should I use to store one key and three values in java?

Question

I am trying to store one name and corresponding left,right,top,bottom dimensions of particular view .I tried with hashmap its storing only (key, value). Please someone tell me which Collection should i use to fulfill my requirement.

for (int i = 0; i < numberOfFaceDetected; i++) {
    android.media.FaceDetector.Face face = myFace[i];
    Log.i("FACE","FACE TAGGING   : "+myFace[i].toString());
    String facename = myFace[i].toString();
    PointF myMidPoint = new PointF();
    face.getMidPoint(myMidPoint);
    myEyesDistance = face.eyesDistance();
    dx = (int) (myMidPoint.x - myEyesDistance);
    dy = (int) (myMidPoint.y - myEyesDistance);
    dz = (int) (myMidPoint.x + myEyesDistance);
    dt = (int) (myMidPoint.y + myEyesDistance);
    //here i want to store facename,dx,dy,dz,dt values in  same  collection
    canvas.drawRect((int) dx, dy, dz, dt, myPaint);
}

This link may help you too... http://stackoverflow.com/questions/4109167/how-can-i-create-a-multimap-in-java-on-android Apart from using a Bean class, Multimaps can also be used. — NamingException, Oct 08 '12 at 12:57
@Naveen: a Multimap is (conceptually) a `Map>`. That would not match the requirement, which is closer to `Map>` (but even that would be wrong; the answer by Anders demonstrates the correct approach). — Joachim Sauer, Oct 08 '12 at 13:07
@joachim sauer: i totally agree with you.... I shared it for giving related information... Thus, provided in comment... :) — NamingException, Oct 08 '12 at 13:40

score 5 · Answer 1 · answered Oct 08 '12 at 11:51

5

How about a Map<YourKeyClass, YourValuesClass>?

Eg.

class YourValuesClass
{
    int dx, dy, dz, dt;

    // getters and setters
    // ...
}

Map<String,YourValueClass> map = new HashMap<String,YourValueClass>();

Cheers,

answered Oct 08 '12 at 11:51

Anders R. Bystrup

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+1 - exactly. The OP is not thinking in terms of objects to a sufficient degree. – duffymo Oct 08 '12 at 11:54
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+1: another case of an OP in [object denial](http://stackoverflow.com/a/3725728/40342). – Joachim Sauer Oct 08 '12 at 12:01

schoeggii · Answer 2 · 2012-10-08T12:02:27.207

i prefer making an object representing the dimensions (three values) and use hashmap key=facename value=faceDimension (your object) in order to fullfill the concept of object oriented programming ;)

public class FaceDimension {
    private int dx;
    private int dy;
    private int dz;
    private int dt;

    public FaceDimension(int dx, int dy, int dz, int dt) {
        super();
        this.dx = dx;
        this.dy = dy;
        this.dz = dz;
        this.dt = dt;
    }
}

score 1 · Answer 3 · edited Oct 08 '12 at 16:28

1

I think using a HashMap would be your best bet.

edited Oct 08 '12 at 16:28

Baz

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answered Oct 08 '12 at 11:55

user1595515

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OP already tried using a HashMap. Telling him **how** to use it would be a good answer. – Baz Oct 08 '12 at 11:56

score 1 · Answer 4 · answered Oct 08 '12 at 12:06

I suggest you to use HashMap, but as you have 4 values corresponding to a key(faceName). Create a Data Transfer Object (DTO) with having four properties to carry the data and put them to the map such as hashMap.put("myface",myDto);

For example,

class Position
{
    private int left;
    private int right;
    private int top;
    private int bottom;
    public int getLeft() {
        return left;
    }
    public void setLeft(int left) {
        this.left = left;
    }
    public int getRight() {
        return right;
    }
    public void setRight(int right) {
        this.right = right;
    }
    public int getTop() {
        return top;
    }
    public void setTop(int top) {
        this.top = top;
    }
    public int getBottom() {
        return bottom;
    }
    public void setBottom(int bottom) {
        this.bottom = bottom;
    }


}

Map<String, Position> faceMap = new HashMap<String, Position>();

Inside your for loop,

Position facePosition = new Position();

facePosition.setLeft(((int) (myMidPoint.x - myEyesDistance)));

set all the properties then faceMap.put("myface",facePosition);

Making `Position` immutable (remove setters, make fields `final`, set values in constructor) would could the lines of code in half (roughly) *and* improve the readability (since you can be sure that a `Position` object never changes "right under you"). — Joachim Sauer, Oct 08 '12 at 12:17
But at the time of retrieving the data ,how we can get the key(face name) ,and value(corresponding left,right,top,bottom positions)? :( — user369932, Oct 09 '12 at 04:37
call the hashMap.get("faceKey"), it will return you the value which you putted. — subodh, Oct 10 '12 at 04:20

Rohit Jain · Answer 5 · 2012-10-08T12:24:17.777

I tried with hashmap its storing only (key, value)

Yeah, but that value can be of any type right?? So, use a List as a value in your HashMap.. So, you can store multiple values..

Map<Integer, List<String>> mapping = new HashMap<Integer, List<String>>();

I have assumed type of key to be Integer and type of values to String.. You can use appropriate type..

Or if you have 4-fixed values, that I just saw you have.. You can create your Custom Type.. just have a class containing all those values, and use HashMap<Integer, YourCustomClass>

public class MyDimension {
    private int top; 
    private int bottom;
    private int right;
    private int left;

    // Your Constructor

    // Use only getters, to make the object immutable..
}

Now, use a HashMap<Integer, MyDimension> with your MyDimension object storing all the 4 values..

Which collection should I use to store one key and three values in java?

5 Answers5