I created button in activity programmaticaly, not in xml file. Then I wanted to set it LayoutParams like in this link: How to programmatically set the layout_align_parent_right attribute of a Button in Relative Layout?
But when I tried to launch, I had an exception.
Here is my code:
RelativeLayout ll2 = new RelativeLayout(this);
//ll2.setOrientation(LinearLayout.HORIZONTAL);
ImageButton go = new ImageButton(this);
go.setId(cursor.getInt(cursor.getColumnIndex("_id")));
go.setClickable(true);
go.setBackgroundResource(R.drawable.go);
RelativeLayout.LayoutParams params1 = (RelativeLayout.LayoutParams)go.getLayoutParams();
params1.addRule(RelativeLayout.ALIGN_PARENT_RIGHT); // LogCat said I have Null Pointer Exception in this line
go.setLayoutParams(params1);
go.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
Intent i3 = new Intent(RecipesActivity.this, MedicineActivity.class);
i3.putExtra(ShowRecipe, v.getId());
i3.putExtra("Activity", "RecipesActivity");
RecipesActivity.this.startActivity(i3);
}
});
ll2.addView(go);
Why my app throws an exception? Thanks.
Change this:
RelativeLayout.LayoutParams params1 = (RelativeLayout.LayoutParams)go.getLayoutParams();
params1.addRule(RelativeLayout.ALIGN_PARENT_RIGHT);
go.setLayoutParams(params1);
for:
RelativeLayout.LayoutParams params1 = new RelativeLayout.LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT);
params1.addRule(RelativeLayout.ALIGN_PARENT_RIGHT);
go.setLayoutParams(params1);
When you create a View programatically it doesn't have any LayoutParams, that's why you are getting NullPointerException. If you inflate the view from XML, the view is coming now with LayoutParams.