Null Pointer Exception when setting LayoutParams
android, imagebutton, layoutparams, nullpointerexception
Solution
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.
Problem
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.