问禁用set按钮后，Android my App崩溃

EN

<android.support.v7.widget.AppCompatButton
    android:id="@+id/btn_print_trans"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_marginTop="40dp"
    android:onClick="OnClickPrintSimpleApiTest"
    android:text="PRINT"
    android:textColor="#FFFFFF" />

public void OnClickPrintSimpleApiTest(View view) {
    final Button BTN_print = (Button) findViewById(R.id.btn_print_trans);
    BTN_print.setBackgroundColor(Color.GREEN);
    BTN_print.setEnabled(false);
}