I'm New to android app development.I have developed a basic app and found null point error at a particular line and added if(instance!=null){do something} .But the part inside if i.e, do something part is never executed.How can I fix this? So that my app works property
public class MainActivity extends ActionBarActivity {
private Button btn1;
private ImageView imagetoshow;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
btn1=(Button)findViewById(R.id.button1);
imagetoshow=(ImageView)findViewById(R.id.imageView1);
if(btn1!=null){
btn1.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
imagetoshow.setImageResource(R.drawable.image1);
}
});
}
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment())
.commit();
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
public PlaceholderFragment() {
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container, false);
return rootView;
}
}
}
