Android startActivityForResult

main1Activity:

public class MainActivity extends AppCompatActivity {public int REQUEST_CODE=0;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        Intent intent = new Intent(MainActivity.this,Main2Activity.class);        intent.putExtra("main","main");        startActivityForResult(intent,0);    }    @Override    protected void onActivityResult(int requestCode, int resultCode, Intent data) {        super.onActivityResult(requestCode, resultCode, data);        switch (resultCode){            case 0:                if (requestCode == REQUEST_CODE){                    String text= data.getStringExtra("hello");                    Toast.makeText(this, text, Toast.LENGTH_SHORT).show();                }                break;        }    }}

main2Activity:

public void go(View view) {    Intent intent = new Intent();    intent.putExtra("hello","hello");    setResult(REST,intent);    finish();}