How can i retrieve this query data ? only retrieve "nama"

dataku.java

package com.example.w8.datasiswa;
public class dataku {
    private String nama;
    private String telp;
    public dataku() {
    }
    public dataku(String nama, String telp){
            this.nama=nama;
            this.telp=telp;
    }

    public String getNama() {return nama;}
    public String getTelp() {return telp;}
}

MainActivity.Java

public class MainActivity extends AppCompatActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Firebase.setAndroidContext(this);

        }

@Override
protected void onStart() {
    super.onStart();
    final Firebase ref = new Firebase("https://datasiswa.firebaseio.com/");
    Button mulai = (Button) findViewById(R.id.BT_Mulai);
    final EditText nama = (EditText) findViewById(R.id.ET_nama);
    final EditText telp = (EditText) findViewById(R.id.ET_telp);

    mulai.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {

            Map<String, String> post1 = new HashMap<String, String>();
            post1.put("Nama", nama.getText().toString());
            post1.put("Telp", telp.getText().toString());
            ref.push().setValue(post1);
        }
    });
    ref.addChildEventListener(new ChildEventListener() {

        @Override
        public void onChildAdded(DataSnapshot dataSnapshot, String s) {
                dataku user = dataSnapshot.getValue(dataku.class);
                System.out.println(user.getNama().toString());
        }
    });
}
}

https://datasiswa.firebaseio.com/ this is my firebase link (structure) how can i retrieve only "nama" every i add child by button ? hehehehehehehe hehehehehehehe hehehehehehehe hehehehehehehe hehehehehehehe hehehehehehehe hehehehehehehe hehehehehehehe hehehehehehehe hehehehehehehe hehehehehehehe