package
com.example.framelayout;
import
android.os.Bundle;
import
android.support.v7.app.ActionBarActivity;
import
android.view.Menu;
import
android.view.MenuItem;
import
android.view.View;
import
android.view.View.OnClickListener;
import
android.widget.Button;
import
android.widget.ImageView;
public
class
MainActivity
extends
ActionBarActivity {
boolean
selected =
true
;
ImageView iv1 = (ImageView)findViewById(R.id.img1);
ImageView iv2 = (ImageView)findViewById(R.id.img2);
@Override
public
void
onCreate(Bundle savedInstanceState) {
super
.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button button1 = (Button)findViewById(R.id.button1);
button1.setOnClickListener(
new
OnClickListener(){
public
void
onClick(View v){
changed();
}
});
}
private
void
changed(){
if
(selected){
iv1.setVisibility(View.INVISIBLE);
iv2.setVisibility(View.VISIBLE);
}
else
{
iv1.setVisibility(View.VISIBLE);
iv2.setVisibility(View.INVISIBLE);
}
selected=!selected;
}
@Override
public
boolean
onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.main, menu);
return
true
;
}
@Override
public
boolean
onOptionsItemSelected(MenuItem item) {
int
id = item.getItemId();
if
(id == R.id.action_settings) {
return
true
;
}
return
super
.onOptionsItemSelected(item);
}
}
logcat
01
-
23
07
:
42
:
54.508
: D/szipinf(
5856
): Initializing inflate state
01
-
23
07
:
42
:
54.518
: D/AndroidRuntime(
5856
): Shutting down VM
01
-
23
07
:
42
:
54.518
: W/dalvikvm(
5856
): threadid=
1
: thread exiting with uncaught exception (group=
0x40015560
)
01
-
23
07
:
42
:
54.528
: E/AndroidRuntime(
5856
): FATAL EXCEPTION: main
01
-
23
07
:
42
:
54.528
: E/AndroidRuntime(
5856
): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.framelayout/com.example.framelayout.MainActivity}: java.lang.NullPointerException
01
-
23
07
:
42
:
54.528
: E/AndroidRuntime(
5856
): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:
1680
)
01
-
23
07
:
42
:
54.528
: E/AndroidRuntime(
5856
): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:
1784
)
01
-
23
07
:
42
:
54.528
: E/AndroidRuntime(
5856
): at android.app.ActivityThread.access$
1500
(ActivityThread.java:
123
)
01
-
23
07
:
42
:
54.528
: E/AndroidRuntime(
5856
): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:
939
)
01
-
23
07
:
42
:
54.528
: E/AndroidRuntime(
5856
): at android.os.Handler.dispatchMessage(Handler.java:
99
)
01
-
23
07
:
42
:
54.528
: E/AndroidRuntime(
5856
): at android.os.Looper.loop(Looper.java:
130
)
01
-
23
07
:
42
:
54.528
: E/AndroidRuntime(
5856
): at android.app.ActivityThread.main(ActivityThread.java:
3835
)
01
-
23
07
:
42
:
54.528
: E/AndroidRuntime(
5856
): at java.lang.reflect.Method.invokeNative(Native Method)
01
-
23
07
:
42
:
54.528
: E/AndroidRuntime(
5856
): at java.lang.reflect.Method.invoke(Method.java:
507
)
01
-
23
07
:
42
:
54.528
: E/AndroidRuntime(
5856
): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:
864
)
01
-
23
07
:
42
:
54.528
: E/AndroidRuntime(
5856
): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:
622
)
01
-
23
07
:
42
:
54.528
: E/AndroidRuntime(
5856
): at dalvik.system.NativeStart.main(Native Method)
01
-
23
07
:
42
:
54.528
: E/AndroidRuntime(
5856
): Caused by: java.lang.NullPointerException
01
-
23
07
:
42
:
54.528
: E/AndroidRuntime(
5856
): at android.app.Activity.findViewById(Activity.java:
1647
)
01
-
23
07
:
42
:
54.528
: E/AndroidRuntime(
5856
): at com.example.framelayout.MainActivity.<init>(MainActivity.java:
14
)
01
-
23
07
:
42
:
54.528
: E/AndroidRuntime(
5856
): at java.lang.Class.newInstanceImpl(Native Method)
01
-
23
07
:
42
:
54.528
: E/AndroidRuntime(
5856
): at java.lang.Class.newInstance(Class.java:
1409
)
01
-
23
07
:
42
:
54.528
: E/AndroidRuntime(
5856
): at android.app.Instrumentation.newActivity(Instrumentation.java:
1021
)
01
-
23
07
:
42
:
54.528
: E/AndroidRuntime(
5856
): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:
1672
)
01
-
23
07
:
42
:
54.528
: E/AndroidRuntime(
5856
): ...
11
more