How to make Model View Presenter on Android

Posted on by

We 4 parts in our android app:

– Model
– View
– Presenter
– Activity

More explanation about this design pattern here.

you can see the complete code here.

In model is the same, nothing new:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
public class SignInRequest implements Serializable {
private String username,name, lastname,password,email;
 
public String getUsername() {
return username;
}
 
public void setUsername(String username) {
this.username = username;
}
 
public String getName() {
return name;
}
 
public void setName(String name) {
this.name = name;
}
 
public String getLastname() {
return lastname;
}
 
public void setLastname(String lastname) {
this.lastname = lastname;
}
 
public String getPassword() {
return password;
}
 
public void setPassword(String password) {
this.password = password;
}
 
public String getEmail() {
return email;
}
 
public void setEmail(String email) {
this.email = email;
}
}

Our view is a interface, and it connects presenter with activity:

1
2
3
4
5
6
7
8
public interface LoginView {
void showLoading(boolean state);
void onRequestSuccess(Object object);
void onRequestError(Object object);
 
Context getContext();
 
}

In presenter We make call, you can use retrofit or any other way, in this case We choose volley:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
public class LoginPresenter {
private static final String TAG ="LoginPresenter" ;
private LoginView loginView;
private RequestQueue queue;
private LoginResponse loginResponse;
 
public LoginPresenter(LoginView loginView) {
this.loginView = loginView;
}
 
public void login(String username, String password)
{
queue = Volley.newRequestQueue(loginView.getContext());
 
final String url = loginView.getContext().getString(R.string.url_login)+"?username="+username+"&password="+password;
final String appID= loginView.getContext().getString(R.string.app_id);
final String key= loginView.getContext().getString(R.string.rest_key);
 
Log.i(TAG, "url " + url);
 
JsonObjectRequest jsonObjReq = new JsonObjectRequest(Request.Method.GET,
url, null,
new Response.Listener()
{
 
@Override
public void onResponse(JSONObject response)
{
Log.i(TAG, "response "+response.toString());
GsonBuilder gsonb = new GsonBuilder();
Gson gson = gsonb.create();
 
loginResponse=null;
try
{
loginResponse= gson.fromJson(response.toString(),LoginResponse.class);
if(loginResponse!=null)
{
Log.i(TAG, "loginResponse "+loginResponse.toString());
loginView.onRequestSuccess(response);
}
 
}catch (Exception e)
{
loginView.onRequestError(e);
}
 
}
}, new Response.ErrorListener() {
 
@Override
public void onErrorResponse(VolleyError error)
{
Log.i(TAG, "Error: " + error);
loginView.onRequestError(error);
}
})
{
@Override
public Map<String, String> getHeaders() throws AuthFailureError {
Map<String, String> params = new HashMap<String, String>();
params.put("X-Parse-Application-Id", appID);
params.put("X-Parse-REST-API-Key", key);
 
return params;
}
};
queue.add(jsonObjReq);
}
 
public void login(Object object)
{
 
}
}

Finally our activity is few lineas and clear code:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
public class LoginActivity extends AppCompatActivity implements LoginView {
 
private static final String TAG = "HomeActivity";
private EditText eteUsername,etePassword;
private View btnLogin,vLoading,tviSignIn;
 
private String username, password;
private LoginPresenter loginPresenter;
 
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
loginPresenter= new LoginPresenter(this);
initiateUI();
}
 
private void initiateUI() {
eteUsername = (EditText)findViewById(R.id.eteUsername);
etePassword = (EditText)findViewById(R.id.etePassword);
btnLogin = findViewById(R.id.btnLogin);
vLoading = findViewById(R.id.vLoading);
tviSignIn = findViewById(R.id.tviSignIn);
vLoading.setVisibility(View.GONE);
events();
}
 
private void events() {
btnLogin.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
 
if (validate()) {
login();
}
}
});
tviSignIn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
gotoSignIn();
}
});
}
 
private boolean validate() {
 
username = eteUsername.getText().toString().trim();
password = etePassword.getText().toString().trim();
 
eteUsername.setError(null);
etePassword.setError(null);
if(username.isEmpty())
{
eteUsername.setError(getString(R.string.msg_ingresar));
return false;
}
if(password.isEmpty())
{
etePassword.setError(getString(R.string.msg_ingresar));
return false;
}
return true;
}
 
private void gotoSignIn() {
 
}
 
private void login()
{
showLoading(true);
loginPresenter.login(username,password);
}
 
@Override
public void showLoading(boolean state) {
int visibility= (state)?(View.VISIBLE):(View.GONE);
vLoading.setVisibility(visibility);
}
 
@Override
public void onRequestSuccess(Object object) {
showLoading(false);
gotoHome();
}
 
@Override
public void onRequestError(Object object) {
showLoading(false);
}
 
private void gotoHome() {
startActivity(new Intent(this,MainActivity.class));
finish();
}
 
@Override
public Context getContext() {
return this;
}
 
@Override
public boolean onCreateOptionsMenu(Menu menu) {
return false;
}
 
@Override
public boolean onOptionsItemSelected(MenuItem item)
{
return false;
}
 
}

You can see the complete code here.

Also more explanation about this design pattern here.

One thought on “How to make Model View Presenter on Android”

  1. Pingback: Model View Presenter on Android • The Developer World Is Yours

Leave a Reply

Your email address will not be published. Required fields are marked *