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What's wrong on this little fragment of Android code

Posted on 2014-02-07
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Last Modified: 2014-02-10
Hi.

I have a little Android app which has a tab control on top to show a relative layout with a background image.

I would like that when user makes a click on the background image, this image change, so I added this code inside the onCreate event:

		findViewById(R.drawable.background1).setOnClickListener(new OnClickListener(){
			@Override
			public void onClick(View v) {
				nextImageEspera();
			}
		});

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With this code, when starting app, it crashes. If I comment this code then all works fine (except the image don't change).

I know the problem is not on nextImageEspera() function because app crashes even if I comment this call.

What is wrong?
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Question by:gplana
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19 Comments
 
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Expert Comment

by:käµfm³d 👽
ID: 39842979
Have you tried debugging it? What is the error message?
0
 
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Expert Comment

by:krakatoa
ID: 39843093
Doesn't this look odd to you :

findViewById(R.drawable.background1)

shouldn't it be more like :

findViewById(R.id.background1);

?
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Expert Comment

by:CEHJ
ID: 39843142
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LVL 15

Author Comment

by:gplana
ID: 39845453
Thank you all for your comments.

This is the logcat just after the app crashed. I have commented the line with the call, so my code is this:

		findViewById(R.drawable.background1).setOnClickListener(new OnClickListener(){
			@Override
			public void onClick(View v) {
				nextImageEspera();
			}
		});

Open in new window


Any help?

Thanks
logErrors.txt
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Expert Comment

by:CEHJ
ID: 39845562
logErrors.txt 0 bytes
The log file is empty
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Author Comment

by:gplana
ID: 39845613
Sorry, it was my fault. Now here are the logs.
logErrors.txt
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Expert Comment

by:CEHJ
ID: 39845887
Please post line 114 of FragmentTabs.java
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Author Comment

by:gplana
ID: 39845907
Is the first line inside function  nextImageEspera:

113      public void nextImageEspera(){
114            RelativeLayout v =(RelativeLayout)findViewById(R.id.root);
115            v.setBackgroundResource(R.drawable.detall_espera);
      }
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Expert Comment

by:krakatoa
ID: 39845918
Could be you are casting to the wrong type somewhere.
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Expert Comment

by:CEHJ
ID: 39845920
That's your problem: it's not a RelativeLayout, so cannot be cast to it
0
 
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Author Comment

by:gplana
ID: 39845936
I think it is:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:background="@drawable/background1"
    android:id="@+id/root"
    tools:context=".MainActivity" >

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Expert Comment

by:CEHJ
ID: 39845942
Nope. You can find out what it is by

System.out.println(findViewById(R.id.root).getClass());

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Author Comment

by:gplana
ID: 39845986
Thank you. You were right. It seems to be a LinearLayout.

After changing this the app doesn't crash anymore but the image still don't change. Why?

This is the code on the function now:

	public void nextImageEspera(){
		System.out.println(findViewById(R.id.root).getClass());
		LinearLayout v =(LinearLayout)findViewById(R.id.root);
		v.setBackgroundResource(R.drawable.detall_espera);
		v.invalidate();
	}

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And I attach logs
log4.txt
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Expert Comment

by:CEHJ
ID: 39846018
Well now i'm at a disadvantage - i don't do Android ;) Try calling repaint?
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Author Comment

by:gplana
ID: 39846525
I have read that invalidate() is the method to do a repaint. Is that not true?
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Expert Comment

by:krakatoa
ID: 39846783
Ha - I don't do Android either, but from sniffing around, one reason could be that your thread is asleep, similar to the effect of running a long-winded command - or calling sleep() - on the Event Dispatch Thread, EDT, in mainstream Java. Maybe check you haven't called sleep() like that.
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Accepted Solution

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CEHJ earned 500 total points
ID: 39846790
I would guess the main purpose of that is to layout the gui again. I know that sometimes with Swing at least, revalidate is insufficient to cause the display to update properly and repaint has to be called as well. So just guessing here
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Author Comment

by:gplana
ID: 39846887
You were right. After some investigation, I have found another way to refresh. This is my current code:

      public void nextImageEspera(){
            System.out.println(findViewById(R.id.root).getClass());
            LinearLayout v =(LinearLayout)findViewById(R.id.root);
            v.setBackgroundResource(R.drawable.detall_espera);
            v.invalidate();
           v.removeAllViews();
             v.refreshDrawableState();
     }

Thanks
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Expert Comment

by:CEHJ
ID: 39846929
Good :)
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