Android应用程序中的奇怪地图行为

Question

I have some strange problem with Map used in my application.

I have a list of objects - Table . Each object has a field which a map of objects of another class:

public class Table {

    private Map<Integer, MyObject> objectsMap = new HashMap<Integer, MyObject>();

    public void addToMap(int i, MyObject mOrder)
    {
        objectsMap.put(i, mOrder);
    }

    public MyObject getObject(int poz)
    {
        return objectsMap.get(poz);
    }

}

public class MyObject {

    private int info1;
    private int info2;

    public void setInfo(int i1, int i2)
    {
        this.info1 = i1;
        this.info2 = i2;
    }

    public int[] getInfos()
    {
        return new int[]{this.info1, this.info2};
    }

}

Then in my main Activity I have some initialization:

private List<Table> tableList = new ArrayList<Table>();

//...

public void initTableObject(Table myTable)
{
    MyObject newObject = new MyObject();
    newObject.setInfo(1,2);
    myTable.addToMap(1, newObject);
    MyObject newObject = new MyObject();
    newObject.setInfo(3,4);
    myTable.addToMap(2, newObject);
    MyObject newObject = new MyObject();
    newObject.setInfo(5,6);
    myTable.addToMap(3, newObject);
    MyObject newObject = new MyObject();
    newObject.setInfo(7,8);
    myTable.addToMap(4, newObject);
}

The problem is when I want to check values:

for (Table table : tableList) {
    int[] info = table.getObject(4).getInfos();
    Log.d("TAG","4: {" + info[0] + ", " + info[1] + "}");
}

When I've got 1 Table object everything is ok. The problem begins when I have 2 or more objects. In case with 2 elements after some interactions (not important in this case) I have problem.

Each time, the last object from map of objects - that is newObject number 4 on the first Table object has the value equal to the 1st object value of 2 element. The second Table object and its MyObject objects are ok.

I was trying everything, and I don't see anything else so this is why I am asking here.

Can someone tell me what is going on here that I am getting this error?

Answer 1

I have been checking it, and it works perfectly for me. I would say that the problem is not with the way Table is defined (the code shown), but in the way you're using it. You're probably modifying the instance of MyObject after you add it to the first Table.

Answer 2

I found an error and solution thanks to your comments.

In fact I've been declaring myObject few times, but it was because if it wasn't like this values were wrong when added to the map in addToMap() method. However, it came out, that this declaration was wrong and I needed to do it directly when I am adding it to the map in mentioned method, so now it looks like this:

public void addToMap(int i, MyObject mOrder)
{
   objectsMap.put(i, new MyObject(mOrder));
}

Also I needed to add proper constructor in MyObject class. And now it is working great.