Question

Hi I wish to change my image height and width depending upon the screen resolution so i am using below code but i am getting error in logcat:

1st my source code :

 public class ImageviewAppActivity extends Activity {

    private ImageView img; 
    private LayoutParams params;
    private int width, height;
    /** Called when the activity is first created. */
    @Override
   public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        height=160; //getWindowManager().getDefaultDisplay().getHeight();
        width = 160; //getWindowManager().getDefaultDisplay().getWidth();

        params = new LayoutParams(width, height);
        img.setLayoutParams(params);

        img =(ImageView) findViewById(R.id.imagetest);
        img.setImageResource(R.drawable.last);
   }}

logcat error:

emulator error:

05-19 20:02:08.689: D/AndroidRuntime(1933): Shutting down VM
05-19 20:02:08.689: W/dalvikvm(1933): threadid=1: thread exiting with uncaught exception (group=0x40015560)
05-19 20:02:08.749: E/AndroidRuntime(1933): FATAL EXCEPTION: main
05-19 20:02:08.749: E/AndroidRuntime(1933): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.test/com.test.ImageviewAppActivity}: java.lang.NullPointerException
05-19 20:02:08.749: E/AndroidRuntime(1933):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647)
05-19 20:02:08.749: E/AndroidRuntime(1933):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
05-19 20:02:08.749: E/AndroidRuntime(1933):     at android.app.ActivityThread.access$1500(ActivityThread.java:117)
05-19 20:02:08.749: E/AndroidRuntime(1933):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
05-19 20:02:08.749: E/AndroidRuntime(1933):     at android.os.Handler.dispatchMessage(Handler.java:99)
05-19 20:02:08.749: E/AndroidRuntime(1933):     at android.os.Looper.loop(Looper.java:123)
05-19 20:02:08.749: E/AndroidRuntime(1933):     at android.app.ActivityThread.main(ActivityThread.java:3683)
05-19 20:02:08.749: E/AndroidRuntime(1933):     at java.lang.reflect.Method.invokeNative(Native Method)
05-19 20:02:08.749: E/AndroidRuntime(1933):     at java.lang.reflect.Method.invoke(Method.java:507)
05-19 20:02:08.749: E/AndroidRuntime(1933):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
05-19 20:02:08.749: E/AndroidRuntime(1933):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
05-19 20:02:08.749: E/AndroidRuntime(1933):     at dalvik.system.NativeStart.main(Native Method)
05-19 20:02:08.749: E/AndroidRuntime(1933): Caused by: java.lang.NullPointerException
05-19 20:02:08.749: E/AndroidRuntime(1933):     at com.test.ImageviewAppActivity.onCreate(ImageviewAppActivity.java:46)
05-19 20:02:08.749: E/AndroidRuntime(1933):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
05-19 20:02:08.749: E/AndroidRuntime(1933):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
05-19 20:02:08.749: E/AndroidRuntime(1933):     ... 11 more
05-19 20:02:08.779: W/ActivityManager(75):   Force finishing activity com.test/.ImageviewAppActivity
05-19 20:02:09.329: W/ActivityManager(75): Activity pause timeout for HistoryRecord{40970fc8 com.test/.ImageviewAppActivity}
05-19 20:02:17.199: D/dalvikvm(378): GC_EXPLICIT freed 7K, 54% free 2537K/5511K, external 1625K/2137K, paused 171ms
05-19 20:02:21.880: W/ActivityManager(75): Activity destroy timeout for HistoryRecord{40970fc8 com.test/.ImageviewAppActivity}

The application ImageviewApp(process com.test.app)has stopped unexpectedly . please try again.

Answer 1

img.setLayoutParams(params);

put above line after this line

img =(ImageView) findViewById(R.id.imagetest);

AND

it your LayoutParams problem, change it check imported package for layourparams and change it…and i dont know which viewgroup you have …but check belows package use one…

import android.widget.RelativeLayout.LayoutParams;

or

import android.view.ViewGroup.LayoutParams;