[android] How to set layout_weight attribute dynamically from code?

How can I set the value for the attribute layout_weight for button in android dynamically from java code ?

Use LinearLayout.LayoutParams:

LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(
    LayoutParams.WRAP_CONTENT, LayoutParams.MATCH_PARENT);
params.weight = 1.0f;
Button button = new Button(this);
button.setLayoutParams(params);

EDIT: Ah, Erich's answer is easier!

If you already define your view in your layout(xml) file, only want to change the weight programmatically, this way is better

LinearLayout.LayoutParams params = (LinearLayout.LayoutParams)   
mButton.getLayoutParams();
params.weight = 1.0f;
mButton.setLayoutParams(params);

new a LayoutParams overwrites other params defined in you xml file like margins, or you need to specify all of them in LayoutParams.

If I someone looking for answer, use this:

LinearLayout.LayoutParams lay = (LinearLayout.LayoutParams) myLayout.getLayoutParams();
lay.weight = 0.5;

If you are initializing your layout from xml file, this will be much more convenient than providing new layout parameters for Linear Layout.

Any of LinearLayout.LayoutParams and TableLayout.LayoutParams worked for me, for buttons the right one is TableRow.LayoutParams. That is:

            TableRow.LayoutParams buttonParams = new TableRow.LayoutParams(
                    TableRow.LayoutParams.MATCH_PARENT,
                    TableRow.LayoutParams.WRAP_CONTENT, 1f);

About using MATCH_PARENT or WRAP_CONTENT be the same.

Using Kotlin you can do something like:

import android.content.Context
import android.support.v4.content.ContextCompat
import android.support.v7.widget.CardView
import android.widget.*

import android.widget.LinearLayout

class RespondTo : CardView {
    constructor(context: Context) : super(context) {
        init(context)
    }

    private fun init(context: Context) {


        val parent = LinearLayout(context)

        parent.apply {
            layoutParams = LinearLayout.LayoutParams(FrameLayout.LayoutParams.MATCH_PARENT,
                    FrameLayout.LayoutParams.WRAP_CONTENT, 1.0f).apply {
                orientation = LinearLayout.HORIZONTAL

                addView(EditText(context).apply {
                    id = generateViewId()
                    layoutParams = LinearLayout.LayoutParams(0,
                            LinearLayout.LayoutParams.WRAP_CONTENT, 0.9f).apply {
                    }
                })
                addView(ImageButton(context).apply({
                    layoutParams = LinearLayout.LayoutParams(0,
                            LinearLayout.LayoutParams.WRAP_CONTENT, 0.1f)
                    background = null
                    setImageDrawable(ContextCompat.getDrawable(context, R.drawable.ic_save_black_24px))
                    id = generateViewId()
                    layoutParams = RelativeLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT,
                            LinearLayout.LayoutParams.WRAP_CONTENT).apply {
                        addRule(RelativeLayout.ALIGN_PARENT_RIGHT)
                        // addRule(RelativeLayout.LEFT_OF, myImageButton.id)
                    }
                }))
            }
        }
        this.addView(parent)
    }
}

If you have already defined your view in layout(xml) file and only want to change the weight pro grammatically, then then creating new LayoutParams overwrites other params defined in you xml file.

So first you should use "getLayoutParams" and then setLayoutParams

LinearLayout.LayoutParams params = (LinearLayout.LayoutParams) mButton.getLayoutParams(); params.weight = 4f; mButton.setLayoutParams(params);

If layoutparams is already defined (in XML or dynamically), Here's a one liner:

((LinearLayout.LayoutParams) mView.getLayoutParams()).weight = 1;

If the constructor with width, height and weight is not working, try using the constructor with width and height. And then manually set the weight.

And if you want the width to be set according to the weight, set width as 0 in the constructor. Same applies for height. Below code works for me.

LinearLayout.LayoutParams childParam1 = new LinearLayout.LayoutParams(0,LinearLayout.LayoutParams.MATCH_PARENT);
childParam1.weight = 0.3f;
child1.setLayoutParams(childParam1);

LinearLayout.LayoutParams childParam2 = new LinearLayout.LayoutParams(0,LinearLayout.LayoutParams.MATCH_PARENT);
childParam2.weight = 0.7f;
child2.setLayoutParams(childParam2);

parent.setWeightSum(1f);
parent.addView(child1);
parent.addView(child2);