Hi,
Iam new to android and I really need help with accessing the xml
layout "objects" from .java. I have this code:
package cz.aurem.ot;
import android.app.Activity;
import android.os.Bundle;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.view.GestureDetector.OnGestureListener;
import android.widget.TextView;
import android.widget.ToggleButton;
import cz.aurem.ot.R;
public class ovladacOT extends Activity implements OnGestureListener {
/** Called when the activity is first created. */
private TextView viewA;
public ToggleButton vypinac;
private GestureDetector gestureScanner;
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
gestureScanner = new GestureDetector(this);
this.vypinac = (ToggleButton)this.findViewById
(R.id.toggle_button);
viewA = (TextView)this.findViewById(R.id.label);
try {
vypinac.setTextOn("LOL");
} catch (Exception ex) {
System.out.print("Exception" + ex.toString());
}
setContentView(R.layout.main);
}
@Override
public boolean onTouchEvent(MotionEvent me)
{
return gestureScanner.onTouchEvent(me);
}
@Override
public boolean onDown(MotionEvent e)
{
viewA.setText("-" + "DOWN" + "-");
return true;
}
@Override
public boolean onFling(MotionEvent e1, MotionEvent e2, float
velocityX, float velocityY)
{
viewA.setText("-" + "FLING" + "-");
return true;
}
@Override
public void onLongPress(MotionEvent e)
{
viewA.setText("-" + "LONG PRESS" + "-");
}
@Override
public boolean onScroll(MotionEvent e1, MotionEvent e2, float
distanceX, float distanceY)
{
viewA.setText("-" + "SCROLL" + "-");
return true;
}
@Override
public void onShowPress(MotionEvent e)
{
viewA.setText("-" + "SHOW PRESS" + "-");
}
@Override
public boolean onSingleTapUp(MotionEvent e)
{
viewA.setText("-" + "SINGLE TAP UP" + "-" + e.getX());
return true;
}
}
AND the main.xml:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/
android"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<ToggleButton android:id="@+id/toggle_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:gravity="center"
android:layout_centerVertical="true"
android:layout_centerHorizontal="true"
android:textOn="Zastavit"
android:textOff="Vpřed"/>
<TextView
android:id="@+id/label"
android:layout_width="200sp"
android:layout_height="200sp"
android:background="#9CEB00"/>
</RelativeLayout>
Everytime I make action (touch the display or so (call the viewA.* or
vypinac.set*)) it crashes due to java.lang.NullPointerException. So it
looks like the
this.vypinac = (ToggleButton)this.findViewById(R.id.toggle_button);
is not works. I dont know what I do bad, please let me know the way or
so.
Thanks in advance :-)
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