...

public class DetailActivity extends AppCompatActivity {
    TextView tvNama, tvNPM, tvAlamat, tvProdi;
    RadioGroup rgDomisili;
    RadioButton rbDK, rbLK;
    CheckBox cbxTeknologi, cbxKuliner;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_detail);

        //definisi widget
        tvNama = (TextView) findViewById(R.id.tv_nama);
        tvNPM = (TextView) findViewById(R.id.tv_npm);
        tvAlamat = (TextView) findViewById(R.id.tv_alamat);
        tvProdi = (TextView) findViewById(R.id.tv_prodi);
        cbxTeknologi = (CheckBox) findViewById(R.id.cb_teknologi);
        cbxKuliner = (CheckBox) findViewById(R.id.cb_kuliner);
        rgDomisili = (RadioGroup) findViewById(R.id.rg_domisili);
        rbDK = (RadioButton) findViewById(R.id.rb_DK);
        rbLK = (RadioButton) findViewById(R.id.rb_LK);

        //tangkap extra yang dikirim dari main activity
        Intent i = getIntent();
        tvNama.setText(i.getStringExtra("x_nama"));
        tvNPM.setText(i.getStringExtra("x_npm"));
        tvAlamat.setText(i.getStringExtra("x_alamat"));
        tvProdi.setText(i.getStringExtra("x_prodi"));
        cbxTeknologi.setChecked(i.getBooleanExtra("x_teknologi", false));
        cbxKuliner.setChecked(i.getBooleanExtra("x_kuliner", false));

        String kelas = i.getStringExtra("x_domisili");
        if (kelas.equals("Luar Kota")){
            rbDK.setChecked(true);
        }else{
            rbLK.setChecked(true);
        }

        /*
        menampilkan tombol back ada 2 tahap
        1. pada manifest harap ditentukan dahulu parent-nya
        android:parentActivityName=".MainActivity"
        2. agar memiliki fungsi yang sama dengan back button kode perlu di override
        onOptionsItemSelected(MenuItem item)
        */

        getSupportActionBar().setTitle("Detail Activity");
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()){
            case android.R.id.home:
                finish();
                return true;
            default:
                return super.onOptionsItemSelected(item);
        }
    }
}