Question

I have four imageviews which are set to invisible at activity start (or rather at row inflation). I would like to press a button and have them ALL become visible (and subsequently be operational as onclicks…). I have the following summary code, but I keep getting errors whenever I try to access any other imageview other than the last one.

public class xx {

    private ImageView up;
        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            // Log.i(TAG, "excersizeAdapter getView");
            View v = convertView;
            if (v == null) {
                LayoutInflater vi = (LayoutInflater)getSystemService(Context.LAYOUT_INFLATER_SERVICE);
                v = vi.inflate(R.layout.row, null);
            }

            Excersize e = items.get(position);
            if (e != null) {
                TextView exTitle      = (TextView) v.findViewById(R.id.ex_type_title);
                TextView exOn         = (TextView) v.findViewById(R.id.ex_on_title);
                TextView exRestAmount = (TextView) v.findViewById(R.id.ex_rest_amount);
                TextView exSequence   = (TextView) v.findViewById(R.id.ex_sequence);

                up                    = (ImageView) v.findViewById(R.id.moveup);
                down                  = (ImageView) v.findViewById(R.id.movedown);

                if (exTitle !=null) {
                    exTitle.setText(e.getTypeTitle());
                }

                if (exOn !=null) {
                    exOn.setText("On: "+e.getTypeOn());
                }

                if (exRestAmount !=null) {
                    exRestAmount.setText(e.getRestAmount().toString());
                }

                if (exSequence !=null) {
                    exSequence.setText(e.getSequence().toString());
                    up.setTag(8881);
                    down.setTag(8882);

                    up.setId(((Integer)e.getSequence()));
                    down.setId(((Integer)e.getSequence()));

                    Log.i(TAG, "up,down values=" +e.getSequence());
                }
            }
            return v;
        }
    }

    public void toggleReorderButtons() {
        up.findViewById(2).setVisibility(View.VISIBLE);
        up.setVisibility(View.VISIBLE);
        up.setOnClickListener(this);
    }
}

OK, this is cut down code, but in the makevisinvis method up.findview... it causes a crash and up.setvis, etc. will turn on only the last one that was added to my activity.

I also tried the following with no success.

ImageView upper = (ImageView) up.findViewById(2);
upper.setVisibility(View.VISIBLE);

A lovely error dump:

04-21 09:10:55.650: W/dalvikvm(22392): threadid=1: thread exiting with uncaught exception (group=0x4001e578)
04-21 09:10:55.675: E/AndroidRuntime(22392): FATAL EXCEPTION: main
04-21 09:10:55.675: E/AndroidRuntime(22392): java.lang.NullPointerException
04-21 09:10:55.675: E/AndroidRuntime(22392):     at com.mediabarltd.digittrainer.ProgramDisplay.toggleReorderButtons(ProgramDisplay.java:437)
04-21 09:10:55.675: E/AndroidRuntime(22392):     at com.mediabarltd.digittrainer.ProgramDisplay.onClick(ProgramDisplay.java:391)
04-21 09:10:55.675: E/AndroidRuntime(22392):     at android.view.View.performClick(View.java:2538)
04-21 09:10:55.675: E/AndroidRuntime(22392):     at android.view.View$PerformClick.run(View.java:9152)
04-21 09:10:55.675: E/AndroidRuntime(22392):     at android.os.Handler.handleCallback(Handler.java:587)
04-21 09:10:55.675: E/AndroidRuntime(22392):     at android.os.Handler.dispatchMessage(Handler.java:92)
04-21 09:10:55.675: E/AndroidRuntime(22392):     at android.os.Looper.loop(Looper.java:130)
04-21 09:10:55.675: E/AndroidRuntime(22392):     at android.app.ActivityThread.main(ActivityThread.java:3691)
04-21 09:10:55.675: E/AndroidRuntime(22392):     at java.lang.reflect.Method.invokeNative(Native Method)
04-21 09:10:55.675: E/AndroidRuntime(22392):     at java.lang.reflect.Method.invoke(Method.java:507)
04-21 09:10:55.675: E/AndroidRuntime(22392):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:907)
04-21 09:10:55.675: E/AndroidRuntime(22392):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:665)
04-21 09:10:55.675: E/AndroidRuntime(22392):     at dalvik.system.NativeStart.main(Native Method)

It took some serious looking and a total rework of what I was doing. but…

Basically I followed the tutorial Android ListView and ListActivity and then implemented the neat ‘trick’ described in Android ListView Adapter OnClickListener issue.

(I’m really having a hard time with this.)

Answer 1

You define up as a class member and re-init it every time getView gets called – therefore it always points to the last image view created. Also, I am not sure it is correct to call findViewById of up: instead set its OnClickListener inside getView and whenever clicked look for the required views inside a layout it belongs to.