[android] How to set layout_gravity programmatically?

My question is simple,

How to set my buttons layout_gravity programmatically?

I found this on internet, but it simply throws me a Nullpointer exception:

 Button MyButton = new Button(this);

    LinearLayout.LayoutParams  lllp=(LinearLayout.LayoutParams)MyButton.getLayoutParams();
    lllp.gravity=Gravity.RIGHT;
    MyButton.setLayoutParams(lllp); 


    MyLinearLayout.addView(MyButton);

Any solution?

FloatingActionButton sendFab = new FloatingActionButton(this);
    FrameLayout.LayoutParams layoutParams = new FrameLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT);
    layoutParams.setMargins(32, 32, 32, 32);
    layoutParams.gravity = Gravity.END|Gravity.BOTTOM;
    sendFab.setLayoutParams(layoutParams);
    sendFab.setImageResource(android.R.drawable.ic_menu_send);

The rest of the answers are right, I want to add more explaination. The layout_gravity is about how to position the view in parent view.

You must set gravity **after method parentView.addView() ** was called. We can see the code:

public void setLayoutParams(ViewGroup.LayoutParams params) {
    if (params == null) {
        throw new NullPointerException("Layout parameters cannot be null");
    }
    mLayoutParams = params;
    resolveLayoutParams();
    if (mParent instanceof ViewGroup) {
        ((ViewGroup) mParent).onSetLayoutParams(this, params);
    }
    requestLayout();
}

And the problem of null pointer is because it's not calling addView before getLayoutParams().

The annotation was already said "This method may return null if this View is not attached to a parent ViewGroup or {@link#setLayoutParams(android.view.ViewGroup.LayoutParams)} was not invoked successfully. When a View is attached to a parent ViewGroup, this method must not return null."

In case you need to set Gravity for a View use the following

Button b=new Button(Context);
b.setGravity(Gravity.CENTER);

For setting layout_gravity for the Button use gravity field for the layoutparams as

LayoutParams lp=new LayoutParams(LayoutParams.WRAP_CONTENT,LayoutParams.WRAP_CONTENT);
lp.gravity=Gravity.CENTER;

try this hope this clears thanks

This question is old but I just had the same problem and solved it like this

LayoutParams lay = new LayoutParams(LayoutParams.FILL_PARENT,LayoutParams.FILL_PARENT)
lay.gravity = Gravity.CENTER;

I use someting like that: (Xamarin and C# code)

  LinearLayout linLayout= new LinearLayout(this); 
    linLayout.SetGravity(GravityFlags.Center);

    TextView txtView= new TextView(this);  
     linLayout.AddView(txtView); 

the SetGravity puts my textView in the center of the layout. So SetGravity layout property refer to layout content

If you want to change the layou_gravity of an existing view do this:

((FrameLayout.LayoutParams) view.getLayoutParams()).gravity = Gravity.BOTTOM;

Remember to use the right LayoutParams based on the Layout type your view is in. Ex:

LinearLayout.LayoutParams

I'd hate to be resurrecting old threads but this is a problem that is not answered correctly and moreover I've ran into this problem myself.

Here's the long bit, if you're only interested in the answer please scroll all the way down to the code:

android:gravity and android:layout_gravity works differently. Here's an article I've read that helped me.

GIST of article: gravity affects view after height/width is assigned. So gravity centre will not affect a view that is done FILL_PARENT (think of it as auto margin). layout_gravity centre WILL affect view that is FILL_PARENT (think of it as auto pad).

Basically, android:layout_gravity CANNOT be access programmatically, only android:gravity. In the OP's case and my case, the accepted answer does not place the button vertically centre.

To improve on Karthi's answer:

LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(
LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
params.gravity = Gravity.CENTER;
button.setLayoutParams(params);

Link to LinearLayout.LayoutParams.

android:layout_gravity shows "No related methods" meaning cannot be access programatically. Whereas gravity is a field in the class.

Perfectly Working!!! None of the above answer works for me. In Xml file setting gravity and setting layout_gravity is different. Check out the below code

// here messageLL is the linear layout in the xml file
// Before adding any view just remove all views
   messageLL.removeAllViews();
// FrameLayout is the parent for LinearLayout
FrameLayout.LayoutParams params = new 
   FrameLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT);
   params.gravity = Gravity.CENTER|Gravity.CENTER_VERTICAL;
   messageLL.setLayoutParams(params);
   messageText.setVisibility(View.GONE);
   messageNoText.setVisibility(View.VISIBLE);
   messageLL.addView(messageNoText);

Also check This,where you can find clear explanation about gravity and layout_gravity .

 int width=getResources().getDisplayMetrics().widthPixels; 
 LinearLayout.LayoutParams params = new LinearLayout.LayoutParams
                    (width, width);

            params.gravity = Gravity.CENTER;

           iv_main_text = new HTextView(getContext());
            iv_main_text.setLayoutParams(params);
            iv_main_text.setBackgroundColor(Color.BLUE);
            iv_main_text.setTextSize(60);
            iv_main_text.setGravity(Gravity.CENTER);
            iv_main_text.setTextColor(Color.BLACK);

KOTLIN setting more than one gravity on FrameLayout without changing size:

     // assign more than one gravity,Using the operator "or"
    var gravity = Gravity.RIGHT or Gravity.CENTER_VERTICAL
     // update gravity
    (pagerContainer.layoutParams as FrameLayout.LayoutParams).gravity = gravity
     // refresh layout
     pagerContainer.requestLayout()

I switched from LinearLayout.LayoutParams to RelativeLayout.LayoutParams to finally get the result I was desiring on a custom circleview I created.

But instead of gravity you use addRule

RelativeLayout.LayoutParams mCircleParams = new RelativeLayout.LayoutParams(circleheight,circleheight);

    mCircleParams.addRule(RelativeLayout.CENTER_IN_PARENT);

Modify the existing layout params and set layout params again

//Get the current layout params and update the Gravity
(iv.layoutParams as FrameLayout.LayoutParams).gravity = Gravity.START
//Set layout params again (this updates the view)
iv.layoutParams = layoutParams

MyButton.setGravity(Gravity.RIGHT);

For layout_gravity use the answer stated by "karthi". This method sets gravity to place the children inside the view.

to RelativeLayout, try this code , it works for me: yourLayoutParams.addRule(RelativeLayout.ALIGN_PARENT_RIGHT);

If you want to put a view in the center of parent, you can do with following code..

public class myLayout extends LinearLayout {

    public myLayout(Context context) {
      super(context);

      RelativeLayout vi = (RelativeLayout) ((LayoutInflater) context
            .getSystemService(Context.LAYOUT_INFLATER_SERVICE)).inflate(
            R.layout.activity_main, null);
      LinearLayout.LayoutParams cc = new LinearLayout.LayoutParams(
            LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
      cc.gravity = Gravity.CENTER;
      this.setGravity(Gravity.CENTER);
      this.addView(vi);
  }
}

these code section make LinearLayout put the first view elements in the center of parent. So, we system don't consider the initial width and high to arrange view in the center . I do the code section well.

layoutParams2.gravity = Gravity.RIGHT|Gravity.BOTTOM;

use this to add mor than one gravity

Try this code

    Button btn = new Button(YourActivity.this);
    btn.setGravity(Gravity.CENTER | Gravity.TOP);
    btn.setText("some text");

or

    btn.setGravity(Gravity.TOP);

I had a similar problem with programmatically setting layout_gravity on buttons in a GridLayout.

The trick was to set gravity on the button layoutParams AFTER the button was added to a parent (GridLayout), otherwise the gravity would be ignored.

grid.addView(button)
((GridLayout.LayoutParams)button.getLayoutParams()).setGravity(int)

Most of above answer are right, so written a helper methods, so you can use it directly in you project .

set layout_gravity programmtically

// gravity types : Gravity.BOTTOM, Gravity.START etc.
// view : can be any view example : button, textview, linearlayout, image etc.

// for single view
   public static void setLayoutGravity(int gravity, View view){
     ((LinearLayout.LayoutParams) view.getLayoutParams()).gravity = gravity;
    }


// for mulitple views
  public static void setLayoutGravity(int gravity, View ...view){
        for(View item : view)
            ((LinearLayout.LayoutParams) item.getLayoutParams()).gravity = gravity;
    }