使用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);

编辑:啊，埃里克的答案更简单!

如果你已经在你的layout(xml)文件中定义了你的视图，只想通过编程改变权重，这种方法更好

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

new a LayoutParams会覆盖xml文件中定义的其他参数，比如页边距，或者你需要在LayoutParams中指定所有的参数。

如果带有width、height和weight的构造函数不起作用，请尝试使用带有width和height的构造函数。然后手动设置权重。

如果您希望根据权重设置宽度，则在构造函数中将width设置为0。身高也是一样。 下面的代码为我工作。

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);

使用Kotlin你可以做以下事情:

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)
    }
}

如果你想设置权重为线性布局，然后使用下面提到的代码或设置权重为相对布局，然后将其替换为相对布局

LinearLayout.LayoutParams param = new LinearLayout.LayoutParams(
LayoutParams.MATCH_PARENT,
LayoutParams.MATCH_PARENT,
1.0f

); YOUR_VIEW.setLayoutParams (param);

如果我有人在寻找答案，用这个:

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

如果你从xml文件初始化布局，这将比为线性布局提供新的布局参数方便得多。