You can use google's FloatingActionButton
XMl:
<android.support.design.widget.FloatingActionButton
android:id="@+id/fab"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="@android:drawable/ic_dialog_email" />
Java:
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
FloatingActionButton bold = (FloatingActionButton) findViewById(R.id.fab);
bold.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
// Do Stuff
}
});
}
Gradle:
compile 'com.android.support:design:23.4.0'