android - AutoCompleteTextView - 如何删除顶部和底部的边距？

Question

我正在使用 AutoCompleteTextView 创建下拉菜单。如何删除列表顶部和底部的默认边距？

重新创建:

<com.google.android.material.textfield.TextInputLayout
        style="@style/Widget.MaterialComponents.TextInputLayout.OutlinedBox.ExposedDropdownMenu"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        app:layout_constraintStart_toStartOf="parent"
        app:boxBackgroundColor="@color/white"
        android:focusable="false"
        app:boxStrokeWidth="1.5dp"
        app:layout_constraintTop_toBottomOf="@+id/spinner_network">

        <AutoCompleteTextView
            android:id="@+id/autoCompleteTextView"
            android:layout_width="250dp"
            android:layout_height="match_parent"
            android:inputType="none"
            android:dropDownHeight="200dp"
            android:text="Select age" />

    </com.google.android.material.textfield.TextInputLayout>

        List<String> dropdownItems = new ArrayList<>();
        for(int i = 1; i <= 100; i++){
            dropdownItems.add(String.valueOf(i));
        }

        ArrayAdapter<String> spinnerAdapter = new ArrayAdapter<>(
                this, R.layout.dropdown_item, dropdownItems
        );

        AutoCompleteTextView autoCompleteTextView = findViewById(R.id.autoCompleteTextView);
        autoCompleteTextView.setAdapter(spinnerAdapter);

R.layout.dropdown_item

<TextView
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/textView"
    android:layout_width="match_parent"
    android:textColor="@color/black"
    android:padding="14dp"
    android:layout_height="wrap_content"
    android:text="TextView" />

Answer 1

---

更新

All the credits and efforts back to @MikeM. from the comments. Many thanks to his efforts.

原因填充来自 TextInputLayout 本身，它的 DropdownMenuEndIconDelegate sets some MaterialShapeDrawables as the dropdown's background .垂直填充的值为 8dp，取自 this resource dimen .

解决方案一:

将此资源维度覆盖为 0dp:

<dimen name="mtrl_exposed_dropdown_menu_popup_vertical_padding" tools:override="true">0dp</dimen>

方案二:

之前的解决方案将应用于所有 AutoCompleteTextView，但如果您想对某些特定的执行此操作:更改默认的 dropDown 背景可绘制对象，例如:

autoCompleteTextView.setDropDownBackgroundDrawable(new ColorDrawable(Color.WHITE));

<罢工>

---

带有反射(不推荐，因为它是反模式)

AutoCompleteTextView 的下拉弹出窗口可以通过 mPopup field 在内部访问.通过反射获得它:

// Java:

public static ListPopupWindow getPopup(AutoCompleteTextView autoCompleteTextView) {
    try {
        Field field = AutoCompleteTextView.class.getDeclaredField("mPopup");
        field.setAccessible(true);
        return (ListPopupWindow) field.get(autoCompleteTextView);
    } catch (NoSuchFieldException e) {
        e.printStackTrace();
    } catch (IllegalAccessException e) {
        e.printStackTrace();
    }
    return null;
}


//  Kotlin:

fun AutoCompleteTextView.getPopup(): ListPopupWindow? {
    try {
        val field = AutoCompleteTextView::class.java.getDeclaredField("mPopup")
        field.isAccessible = true
        return field.get(this) as ListPopupWindow
    } catch (e: NoSuchFieldException) {
        e.printStackTrace()
    } catch (e: IllegalAccessException) {
        e.printStackTrace()
    }
    return null
}

然后通过将其设置为内部 ListView 的父 View 来移除填充:

// Java:

autoCompleteTextView.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        ListPopupWindow popup = getPopup(autoCompleteTextView);
        if (popup != null) {
            ListView listView = popup.getListView();
            if (listView!= null)
                ((View) listView.getParent()).setPadding(0, 0, 0, 0);
        }
    }
});

// Kotlin

autoCompleteTextView.setOnClickListener {
    val popUp = autoCompleteTextView2.getPopup()?.listView?.parent
    if (popUp != null)
        (popUp as View).setPadding(0, 0, 0, 0)
}

这是在 OnClickListener 中完成的，因为当用户点击列表时，可空性检查将不匹配，因为列表已形成。