Got it, I’ve dealt with this exact frustration before—nothing’s more annoying than setting a button to be semi-transparent only to watch the text fade out too! The key here is to apply transparency only to the button’s background, not the entire button view itself. Here are a few straightforward ways to pull this off:

1. Use a Custom Drawable Background (Most Universal Approach) #

This works for all button types, whether you’re using the basic Button or a Material Design component.

First, create a new drawable file in res/drawable (name it something like btn_semi_transparent_bg.xml):

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">
    <!-- Use a color with alpha value (first two hex digits = transparency) -->
    <!-- Example: #80FF0000 = 50% transparent red -->
    <solid android:color="#80FF0000" />
    <!-- Optional: Add rounded corners if you want -->
    <corners android:radius="8dp" />
</shape>

Then apply this drawable as your button’s background in your layout XML:

<Button
    android:id="@+id/my_button"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Opaque Text Here"
    android:textColor="#FF000000" <!-- Fully opaque text color -->
    android:background="@drawable/btn_semi_transparent_bg" />

2. Use MaterialButton’s Built-in Tinting (If Using Material Design) #

If you’re using MaterialButton from the Material Components library, you can skip the custom drawable and directly set a semi-transparent background tint:

<com.google.android.material.button.MaterialButton
    android:id="@+id/material_button"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Opaque Text"
    android:textColor="#FF000000"
    app:backgroundTint="#804CAF50" <!-- 50% transparent green -->
    app:cornerRadius="8dp" />

3. Set Transparency Dynamically in Code #

If you need to adjust the button’s transparency at runtime, use ColorUtils to modify the background color’s alpha without touching the text:

// Kotlin example
val button = findViewById<Button>(R.id.my_button)
val originalColor = ContextCompat.getColor(this, R.color.your_button_color)
// Set alpha (0 = fully transparent, 255 = fully opaque)
val semiTransparentColor = ColorUtils.setAlphaComponent(originalColor, 128)
button.setBackgroundColor(semiTransparentColor)

// Java example
Button button = findViewById(R.id.my_button);
int originalColor = ContextCompat.getColor(this, R.color.your_button_color);
int semiTransparentColor = ColorUtils.setAlphaComponent(originalColor, 128);
button.setBackgroundColor(semiTransparentColor);

Important Note #

Avoid using button.setAlpha()—this method applies transparency to the entire button view, including its text, which is exactly what you’re trying to avoid. Always target the background instead!

内容的提问来源于stack exchange，提问作者camjames