以编程方式创建的ImageButtons中定义的putExtra数据仅看到最后一个值？

Question

I have programatically defined a set of imagebuttons in a for loop. For each button, I defined its setOnClickListener function which will put some data in the intent and then switch activity. However, it seems like no matter which button I clicked on, the extra data retrieved is set the the last value int he for loop. See code here:

public void onCreate(Bundle savedInstanceState) {
   <...>

        RelativeLayout rl = (RelativeLayout) findViewById(R.id.rlayout);

        for (int i=1; i<=maxMapLoc; i++ ) {
            mapLocation = i;
            ImageButton btnMapLoc = new ImageButton(FirstActivity.this);
            RelativeLayout.LayoutParams vp = new RelativeLayout.LayoutParams(
                    LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
            btnMapLoc.setLayoutParams(vp);
            btnMapLoc.setBackgroundColor(Color.TRANSPARENT);
            btnMapLoc.requestLayout();
            String imgName = "map_loc_" + mapLocation;                
            int id = getResources().getIdentifier(imgName,"drawable",getPackageName());
            btnMapLoc.setImageResource(id);
            int imgMapLoc = 2000 + mapLocation;
            btnMapLoc.setId(imgMapLoc);
            rl.addView(btnMapLoc, vp);

            btnMapLoc.setOnClickListener(new View.OnClickListener() {
                public void onClick(View v) {
                    Intent intent = new Intent(FirstActivity.this, SecondActivity.class);
                    intent.putExtra("MapLocation", mapLocation);

                    startActivity(intent);

                }
            });

Any idea what I did wrong?

Thanks.

Answer 1

You could add a tag to your button with the current mapLocation value.

btnMapLoc.setTag(i);
...

// In onClick
    intent.putExtra("MapLocation", v.getTag());
    ...

The reason why you only get the last value of mapLocation is that the code inside your onClick() is run when the user pushes a button. In other words your are querying mapLocation long after the loop built your buttons. You need to create a reference to the current mapLocation in each loop iteration, like with the tag feature.