如何请求专注于开始活动

Question

所以当我的scanactivity启动我的cardnumberbox请求焦点时 从这里我扫描一些将被粘贴到cardnumberbox然后的条形码 我的shelfnumberbox请求焦点，然后我启动我的camactivity，我只是拍了一些照片，然后我回到我的扫描活动但是我的cardnumberbox再次聚焦而不是shelfnumberbox

那么当我从我的camactivity启动扫描活动时，如何让我的shelfnumberbox获得焦点

//Scan activity
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        cardnumberbox.requestFocus();}
        String k = getIntent().getStringExtra("cardid");
        cardnumberbox.setText(k);
}
 cardnumberbox.addTextChangedListener(new TextWatcher() {
            @Override
            public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {

            }

            @Override
            public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {
                String text1 = cardnumberbox.getText().toString().trim();
                if (text1.equals("R")) {
                    Toast.makeText(getApplicationContext(), getString(R.string.Skan_Udfyld_Kort_Nummer), Toast.LENGTH_SHORT).show();
                    cardnumberbox.setText("");
                    cardnumberbox.requestFocus();
                } else if (cardnumberbox.getText().toString().length() > 0) {
                    shelfnumberbox.requestFocus();
                }
                {
                }
            }

//cam activity
    public void btn_aprove2(View view) {
        Intent i = new Intent(CameraActivity.this, ScanActivity.class);
        String carde = cardnumberbox2.getText().toString().trim();
        i.putExtra("cardid", carde);
        startActivity(i);
    }