如何设置android:layout_marginBottom程序？

要在屏幕上拖动图像，我创建了自己的类：

private class CustomImageView extends AppCompatImageView

在构造函数中，我要设置参数：

public CustomImageView(Context context) {
    super(context);
    params = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.MATCH_PARENT, RelativeLayout.LayoutParams.MATCH_PARENT);
    params.bottomMargin = 50;
    this.setScaleType(ImageView.ScaleType.CENTER_CROP);
    this.setLayoutParams(params);
    this.setWillNotDraw(false);
}

my activity_main.xml：

<RelativeLayout 
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.eleizo.firstapplication.MainActivity">   
</RelativeLayout>

我想要的实际上是：

<RelativeLayout 
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.eleizo.firstapplication.MainActivity">

    <ImageView
        android:id="@+id/map"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:scaleType="centerCrop"
        android:layout_marginBottom="50dp"
        />
</RelativeLayout>

为什么字符串“params.bottomMargin=50”不起作用？我试图设置

params=newrelativelayout.LayoutParams（val1，val2）

，但没关系。

---

如何设置android:layout_marginBottom在RelativeLayout by code中的设置？

尝试使用

MarginLayoutParams

而不是

LayoutParams

if( params instanceof MarginLayoutParams )
{
    ((MarginLayoutParams) params).bottomMargin = 50;
    ((MarginLayoutParams) params).leftMargin = 10;

}

所以你的代码看起来像

public CustomImageView(Context context) {
    super(context);
    params = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.MATCH_PARENT, RelativeLayout.LayoutParams.MATCH_PARENT);

    if( params instanceof MarginLayoutParams )
    {
    ((MarginLayoutParams) params).bottomMargin = 50;
    }
    this.setScaleType(ImageView.ScaleType.CENTER_CROP);
    this.setLayoutParams(params);
    this.setWillNotDraw(false);

---

}

尝试使用

marginlayoutparms

而不是

layoutparms

if( params instanceof MarginLayoutParams )
{
    ((MarginLayoutParams) params).bottomMargin = 50;
    ((MarginLayoutParams) params).leftMargin = 10;

}

所以你的代码看起来像

public CustomImageView(Context context) {
    super(context);
    params = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.MATCH_PARENT, RelativeLayout.LayoutParams.MATCH_PARENT);

    if( params instanceof MarginLayoutParams )
    {
    ((MarginLayoutParams) params).bottomMargin = 50;
    }
    this.setScaleType(ImageView.ScaleType.CENTER_CROP);
    this.setLayoutParams(params);
    this.setWillNotDraw(false);

---

}

在相对布局中添加视图时，请尝试使用LayoutParams

像这样的

RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.MATCH_PARENT, RelativeLayout.LayoutParams.MATCH_PARENT);
params.bottomMargin = 50;

relativeLayout.addView(new CutomImageView(context), params);

---

在相对布局中添加视图时，请尝试使用LayoutParams

像这样的

RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.MATCH_PARENT, RelativeLayout.LayoutParams.MATCH_PARENT);
params.bottomMargin = 50;

relativeLayout.addView(new CutomImageView(context), params);