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

尝试从 AutoCompleteTextView

中删除 dropDownHeight 属性

android:dropDownHeight="200dp" --> remove this line

并将您的 AutoCompleteTextView 高度设置为 wrap_content。

Answer 2

---

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. The value of the vertical padding is 8dp which taken from this resource dimen.

解决方案 1：

将此资源维度覆盖为 0dp:

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

解决方案 2：

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));

---

带反射（不推荐，因为它是反模式）

mPopup field 可以在内部访问 AutoCompleteTextView 的下拉弹出窗口。要通过反射获得它：

// 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的父视图来删除填充 ListView:

// 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。

Answer 3

它不会让我编辑答案，而是 https://whosebug.com/users/2850651/mike-m 的另一个解决方案 删除填充：

在 autoCompleteTextView 中调用 .showDropDown() .setOnClickListener()

<com.google.android.material.textfield.MaterialAutoCompleteTextView
        android:id="@+id/autoCompleteTextView"
        android:layout_width="250dp"
        android:layout_height="50dp"
        android:drawableEnd="@drawable/ic_arrow_drop_down"
        android:dropDownHeight="200dp"
        android:inputType="none"
        android:text="Select age" 
        ...../>

List<String> dropdownItems = new ArrayList<>();
for (int i = 1; i <= 10; i++) {
     dropdownItems.add(String.valueOf(i));
}

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


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

//.showDropDown() removes the padding
autoCompleteTextView.setOnClickListener(v -> autoCompleteTextView.showDropDown());