Android how to make button text bold when pressed or focussed

Attention! See update below

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You could create your own style.xml in which you define the text style. In your selector you can reference to the style. style.xml

<style name="myStyle">  
    <item name="android:textSize">9px</item>
    <item name="android:gravity">center_horizontal</item>
    <item name="android:textColor">#fff</item>
    <item name="android:textStyle">bold</item>
</style>

And in your selector

<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item android:state_focused="true"
      android:state_pressed="false" 
      style="@style/myStyle" /> </selector>

Update 2020: My answer is more than 10 years old. It doesn´t work anymore!

You could try putting the bold code inside the click event for the button:

final Button button = (Button) findViewById(R.id.button_id);
         button.setOnClickListener(new View.OnClickListener() {
             public void onClick(View v) {
                 // Set bold on click
                 button.setTypeface(null, Typeface.BOLD);
             }
         });