how to give button rounded edge android studio code example

Example 1: how to add cardview in android studio

dependencies {
    implementation 'com.android.support:cardview-v7:28.0.0'
}

Example 2: android studio change image on button click

ImageButton btn = (ImageButton)findViewById(R.id.imageButton1);       
 btn.setImageResource(R.drawable.actions_record);