如何在 android studio 中的按钮上方放置标签？

Question

我想设计一个消息按钮，该按钮附加到显示消息数量的标签上。喜欢下图

我用 android studio 设计的，但是标签没有正确对齐。我怎样才能把它放在按钮的顶部？

这是我的代码

<?xml version="1.0" encoding="utf-8"?>
    <androidx.constraintlayout.widget.ConstraintLayout    
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".HomeActivity">


    <Button
        android:id="@+id/msg"
        android:layout_width="157dp"
        android:layout_height="42dp"
        android:background="@color/lightgrey"
        android:backgroundTint="#@color/lightgrey"
        android:text="Messages"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.206" />

    <TextView
        android:id="@+id/mark"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:background="@drawable/rounded_textview"
        android:gravity="center"
        android:text="2"
        android:textColor="@color/lightgrey"
        android:textSize="20sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.662"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.17" />



</androidx.constraintlayout.widget.ConstraintLayout>

Answer 1

您可以使用 BadgeDrawable.

val badge = BadgeDrawable.create(this)
BadgeUtils.attachBadgeDrawable(badge, yourButton)
// usage
badge.number = 5

Answer 2

您需要删除附加到父项的 TextView 的任何约束，并使 TextView 仅约束到 Button

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".HomeActivity">

    <Button
        android:id="@+id/msg"
        android:layout_width="157dp"
        android:layout_height="42dp"
        android:background="@color/lightgrey"
        android:backgroundTint="#@color/lightgrey"
        android:text="Messages"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintVertical_bias="0.206"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/mark"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:background="@drawable/rounded_textview"
        android:gravity="center"
        android:text="2"
        android:textColor="@color/lightgrey"
        android:textSize="20sp"
        android:elevation="10dp"
        app:layout_constraintBottom_toTopOf="@+id/msg"
        app:layout_constraintEnd_toEndOf="@id/msg"
        app:layout_constraintStart_toEndOf="@id/msg"
        app:layout_constraintTop_toTopOf="@id/msg" />


</androidx.constraintlayout.widget.ConstraintLayout>

预览

如何在 android studio 中的按钮上方放置标签？

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label

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android-layout

android-constraintlayout