如何为ConstraintLayout添加边框及标题，实现带锁定编辑的EditText样式

Hey there! The issue with your floating title is that Android doesn't allow negative padding values—those get ignored automatically. Instead, we can use negative margins and adjust the layout constraints properly to get that floating label effect you want, just like a Material Design EditText. Let's walk through the solution step by step.

Step 1: Keep Your Border Shape #

First, keep your existing shape drawable (save it as res/drawable/edittext_border.xml—it works perfectly for the border):

<shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="rectangle">
    <solid android:color="@android:color/transparent" />
    <stroke android:width="1dp" android:color="#6B000000" />
    <corners android:radius="4dp" />
</shape>

Step 2: Build the ConstraintLayout with Floating Title #

Instead of using negative padding on the TextView, we'll use negative marginTop (which is allowed) and add a background to the TextView to cover the border underneath it. Here's the full layout code:

<androidx.constraintlayout.widget.ConstraintLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:background="@drawable/edittext_border"
    android:padding="16dp"> <!-- Padding keeps inner content from overlapping the title -->

    <!-- Floating Title Label -->
    <TextView
        android:id="@+id/tv_section_title"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/title"
        android:textColor="@color/logoDark"
        android:textSize="12sp"
        android:background="#FFFFFF" <!-- Match your screen/parent background color -->
        android:paddingHorizontal="4dp" <!-- Adds space around text so it doesn't touch the border -->
        android:layout_marginStart="8dp"
        android:layout_marginTop="-8dp" <!-- Negative margin pulls the title up over the border -->
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <!-- Editable Value (use EditText for editable fields) -->
    <EditText
        android:id="@+id/editable_value"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="123"
        android:background="@null" <!-- Removes default EditText border -->
        android:inputType="number" <!-- Restrict to numeric input if needed -->
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@id/tv_section_title" />

    <!-- Locked Value (use TextView for non-editable fields) -->
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Locked: 456"
        android:textColor="@color/black"
        android:layout_marginStart="16dp"
        app:layout_constraintStart_toEndOf="@id/editable_value"
        app:layout_constraintTop_toBottomOf="@id/tv_section_title" />

</androidx.constraintlayout.widget.ConstraintLayout>

Key Details to Note: #

• Negative Margin Instead of Padding: Android ignores negative padding, but negative margins let you shift the TextView upward so it overlaps the top border of the ConstraintLayout.
• TextView Background: Setting a background color that matches your parent layout (e.g., white) covers the border underneath the title, making it look like the label is floating on top of the border.
• Inner Padding: The padding="16dp" on the ConstraintLayout ensures your editable/locked values don't overlap with the title or border.
• Controlling Editability: Use EditText for values you want users to modify, and TextView (or set EditText.setEnabled(false)) for locked values.

This setup will give you a ConstraintLayout with a clean floating title, border, and precise control over which values are editable.

内容的提问来源于stack exchange，提问作者user14016776