Android findViewById从searchView返回null

我试图从searchView中删除Underline，但findViewById方法始终返回null

@Override
protected void onResume() {
    super.onResume();
    View view = mSearchView.findViewById(android.support.v7.appcompat.R.id.search_plate);
    view.setBackgroundColor(Color.TRANSPARENT);
}

---

在

onCreate中初始化SearchView

    @Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);


    searchView = findViewById(R.id.search);
    View v = searchView.findViewById(android.support.v7.appcompat.R.id.search_plate);
    v.setBackgroundColor(Color.TRANSPARENT);

}

布局
R.layout.activity\u main

   <android.support.v7.widget.SearchView
    android:id="@+id/search"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_marginStart="8dp"
    android:layout_marginTop="8dp"
    android:layout_marginEnd="8dp"
    android:layout_marginBottom="8dp"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent" />

在您的
onCreate中初始化SearchView

    @Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);


    searchView = findViewById(R.id.search);
    View v = searchView.findViewById(android.support.v7.appcompat.R.id.search_plate);
    v.setBackgroundColor(Color.TRANSPARENT);

}

布局
R.layout.activity\u main

   <android.support.v7.widget.SearchView
    android:id="@+id/search"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_marginStart="8dp"
    android:layout_marginTop="8dp"
    android:layout_marginEnd="8dp"
    android:layout_marginBottom="8dp"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent" />


你能分享你的xml文件吗？你能分享你的xml文件吗？我想知道为什么现在，我改进了android.widget.SearchView，但试图将它用作android.support.v7.widget.SearchView，但无论如何我想知道为什么现在，我改进了android.widget.SearchView，但试图将它用作android.support.v7.widget.SearchView，但无论如何