结合的观点

Question

当在我布局我改变一个TextView的边缘有一个TextView像RelativeLayout下面的内部：

<?xml version="1.0" encoding="utf-8"?> 
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    xmlns:app="http://schemas.android.com/apk/res-auto" 
    android:layout_width="match_parent" 
    android:layout_height="80dp" 
    android:orientation="horizontal"> 

    <TextView 
     android:id="@+id/textView17" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:layout_alignParentLeft="true" 
     android:layout_alignParentStart="true" 
     android:layout_alignParentTop="true" 
     android:layout_marginLeft="70dp" 
     android:layout_marginStart="70dp" 
     android:layout_marginTop="12dp" 
     android:layout_toLeftOf="@+id/imageButton2" 
     android:layout_toStartOf="@+id/imageButton2" 
     android:text="TextView" 
     android:textColor="@android:color/black" 
     android:textSize="24sp" 
     android:textStyle="bold" /> 

的left margins在这种情况下，明确设置为70dp。但是，我想有条件地将left margin减少到30dp左右。我这样做的尝试是这样的：

@Override 
public void onBindItemViewHolder(RecyclerView.ViewHolder holder, int position) { 
    final Material m = ... 
    ViewHolder h = (ViewHolder) holder; 

    h.checkedImageview.setVisibility(View.GONE); 

    RelativeLayout.LayoutParams layoutParams = (RelativeLayout.LayoutParams) h.titleTextview.getLayoutParams(); 
    layoutParams.setMargins(
      20, 
      layoutParams.topMargin, 
      layoutParams.rightMargin, 
      layoutParams.bottomMargin 
    ); 
    h.titleTextview.setLayoutParams(layoutParams); 

^^但是，那根本没有任何效果。如果我修改XML布局中的值，它是否可以正常工作？我究竟做错了什么？我使用SectionedRecyclerViewAdapterRecyclerView库，如果这很重要的话。

Answer 1

例如：

public static class PersonViewHolder extends RecyclerView.ViewHolder { 

CardView cv; 
TextView personName; 
TextView personAge; 
ImageView personPhoto; 

PersonViewHolder(View itemView) { 
    super(itemView); 
    cv = (CardView)itemView.findViewById(R.id.cv); 
    personName = (TextView)itemView.findViewById(R.id.person_name); 
    personAge = (TextView)itemView.findViewById(R.id.person_age); 
    personPhoto = (ImageView)itemView.findViewById(R.id.person_photo); 
} 

}

，所以我读git的枢纽页面胡斯托做到这一点：

@Override 
public void onBindItemViewHolder(PersonViewHolder holder, int position) { 

    //here --->>> 
    PersonViewHolder itemHolder = (PersonViewHolder) holder; // important ! 

    holder.checkedImageview.setVisibility(View.GONE); 

    RelativeLayout.LayoutParams layoutParams = (RelativeLayout.LayoutParams) holder.titleTextview.getLayoutParams(); 
    layoutParams.setMargins(
      20, 
      layoutParams.topMargin, 
      layoutParams.rightMargin, 
      layoutParams.bottomMargin 
    ); 
    holder.titleTextview.setLayoutParams(layoutParams); 

Answer 2

的问题是，你打算重用从现有LayoutParams文本视图。不要重复使用，请创建一个新的对象，设置其边距，然后适当设置TextView的参数。代码：

RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams 
    (ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT); 

params.setMargins(0, 0, 0, 0); // or any other values 

textView.setLayoutParams(params);