Android Live Data Tutorial | Live Data | Data Binding | Architecture Components

Hello Friends,
              Today I am going to share me small tutorial of LiveData with Data Binding.

-What is LiveData?
     LiveData is an observable data holder class that can be observed within
     a given lifecycle. It lets the components in your app, usually the UI,
     observe LiveData objects for changes.

-The advantages of using LiveData

•      Ensures your UI matches your data state
•      No memory leaks
•      No crashes due to stopped activities
•      No more manual lifecycle handling
•      Always up to date data
•      Proper configuration changes
•      Sharing resources

-How to use it in our app

   a. Add below dependency in app/build.gradle

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1. implementation "android.arch.lifecycle:extensions:1.1.1"   

implementation "android.arch.lifecycle:extensions:1.1.1" 

   
   b. UserViewModel.java : Creating a ViewModel class

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1. package com.android.developer.livedatademo.model;  
2.   
3. import android.arch.lifecycle.MutableLiveData;  
4. import android.arch.lifecycle.ViewModel;  
5.   
6. /** 
7.  * Created by mukesh on 13/6/18. 
8.  */  
9. public class UserViewModel extends ViewModel {  
10.   
11.     // Create a LiveData with a String  
12.     private MutableLiveData<user> mUser;  
13.   
14.     public MutableLiveData<user> getUser() {  
15.         if (mUser == null) {  
16.             mUser = new MutableLiveData<user>();  
17.         }  
18.         return mUser;  
19.     }  
20. }   
21. </user></user></user>  

package com.android.developer.livedatademo.model;

import android.arch.lifecycle.MutableLiveData;
import android.arch.lifecycle.ViewModel;

/**
 * Created by mukesh on 13/6/18.
 */
public class UserViewModel extends ViewModel {

    // Create a LiveData with a String
    private MutableLiveData mUser;

    public MutableLiveData getUser() {
        if (mUser == null) {
            mUser = new MutableLiveData();
        }
        return mUser;
    }
} 

In Activity class we creates an observer which updates the ui.

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1. final Observer<user> nameObserver = new Observer<user>() {  
2.       @Override  
3.       public void onChanged(@Nullable final User user) {  
4.       // Update the UI, in this case, a TextView.  
5.       binding.tvUserName.setText(user.getName());  
6.     }  
7. };  
8. </user></user>  

final Observer nameObserver = new Observer() {
      @Override
      public void onChanged(@Nullable final User user) {
      // Update the UI, in this case, a TextView.
      binding.tvUserName.setText(user.getName());
    }
};

Next step is observe the livedata, passing in the activity as a LifecycleOwner and the Observer.

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1. userViewModel.getUser().observe(this, nameObserver);  
2. binding.btnClick.setOnClickListener(this);   

userViewModel.getUser().observe(this, nameObserver);
binding.btnClick.setOnClickListener(this); 

The complete code,

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1. package com.android.developer.livedatademo;  
2.   
3. import android.arch.lifecycle.Observer;  
4. import android.arch.lifecycle.ViewModelProviders;  
5. import android.databinding.DataBindingUtil;  
6. import android.support.annotation.Nullable;  
7. import android.support.v7.app.AppCompatActivity;  
8. import android.os.Bundle;  
9. import android.view.View;  
10.   
11. import com.android.developer.livedatademo.databinding.ActivityMainBinding;  
12. import com.android.developer.livedatademo.model.User;  
13. import com.android.developer.livedatademo.model.UserViewModel;  
14.   
15. public class MainActivity extends AppCompatActivity implements View.OnClickListener {  
16.   
17.     UserViewModel userViewModel;  
18.     ActivityMainBinding binding;  
19.     @Override  
20.     protected void onCreate(Bundle savedInstanceState) {  
21.         super.onCreate(savedInstanceState);  
22.         binding = DataBindingUtil.setContentView(this, R.layout.activity_main);  
23.         // Get the ViewModel.  
24.         userViewModel = ViewModelProviders.of(this).get(UserViewModel.class);  
25.         // Create the observer which updates the UI.  
26.         final Observer<user> nameObserver = new Observer<user>() {  
27.             @Override  
28.             public void onChanged(@Nullable final User user) {  
29.                 // Update the UI, in this case, a TextView.  
30.                 binding.tvUserName.setText(user.getName());  
31.             }  
32.         };  
33.   
34.         // Observe the LiveData, passing in this activity as the LifecycleOwner and the observer.  
35.         userViewModel.getUser().observe(this, nameObserver);  
36.         binding.btnClick.setOnClickListener(this);  
37.     }  
38.   
39.     @Override  
40.     public void onClick(View v) {  
41.         User user = new User();  
42.         user.setName("Mukesh Yadav");  
43.         user.setAge("25");  
44.         userViewModel.getUser().setValue(user);  
45.     }  
46. }   
47. </user></user>  

package com.android.developer.livedatademo;

import android.arch.lifecycle.Observer;
import android.arch.lifecycle.ViewModelProviders;
import android.databinding.DataBindingUtil;
import android.support.annotation.Nullable;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;

import com.android.developer.livedatademo.databinding.ActivityMainBinding;
import com.android.developer.livedatademo.model.User;
import com.android.developer.livedatademo.model.UserViewModel;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

    UserViewModel userViewModel;
    ActivityMainBinding binding;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        binding = DataBindingUtil.setContentView(this, R.layout.activity_main);
        // Get the ViewModel.
        userViewModel = ViewModelProviders.of(this).get(UserViewModel.class);
        // Create the observer which updates the UI.
        final Observer nameObserver = new Observer() {
            @Override
            public void onChanged(@Nullable final User user) {
                // Update the UI, in this case, a TextView.
                binding.tvUserName.setText(user.getName());
            }
        };

        // Observe the LiveData, passing in this activity as the LifecycleOwner and the observer.
        userViewModel.getUser().observe(this, nameObserver);
        binding.btnClick.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        User user = new User();
        user.setName("Mukesh Yadav");
        user.setAge("25");
        userViewModel.getUser().setValue(user);
    }
} 

Download the complete code here

Hope this will helps someone.
Enjoy Coding... :)