Android点击按钮拨打电话

public void callPhone(String str) {
    Intent intent=new Intent();
    intent.setAction(Intent.ACTION_DIAL);
    intent.setData(Uri.parse("tel:" + str));
    startActivity(intent);
}

setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    callPhone("18888888888");
}