AutoCompleteTextView - 如何从顶部和底部删除边距？

Question

I'm creating a dropdown menu using AutoCompleteTextView . How do I remove the default margins at the top and bottom of the list?

To recreate:

<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

Try removing dropDownHeight attribute from the AutoCompleteTextView

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

And also set your AutoCompleteTextView height as wrap_content .

Answer 2

Meanwhile I don't think there is a direct API that allows you to do that; but you can achieve it with reflections as a last resort. Hopefully there would be an API, as reflections is anti-pattern.

The drop down popup of the AutoCompleteTextView can be accessed internally by mPopup field . To get it with reflections:

// 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
}

Then remove the padding by setting it to the parent view of the internal 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)
}

This is done in OnClickListener because the nullability checks won't match as the list is formed when the user hits it.

Answer 3

It won't let me edit the answer but another solution by https://stackoverflow.com/users/2850651/mike-m to remove padding:

Calling .showDropDown() in autoCompleteTextView 's .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());