MVVM

Library

    def lifecycle_version = "1.1.1"
// ViewModel and LiveData    

implementation "android.arch.lifecycle:extensions:$lifecycle_version"

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>

<layout xmlns:android="http://schemas.android.com/apk/res/android"    

xmlns:app="http://schemas.android.com/apk/res-auto">
    <data>
        <variable            

name="viewModel"            

type="com.app.testapp.UserProfileViewModel" />
    </data>
<LinearLayout    

android:layout_width="match_parent"    

android:layout_height="match_parent"    

android:orientation="vertical"    >
    <LinearLayout        

android:layout_width="match_parent"        

android:layout_height="match_parent"        

android:orientation="vertical"        >
        <TextView            

android:id="@+id/textView"            

android:layout_width="wrap_content"            

android:layout_height="wrap_content"            

android:textColor="@color/colorPrimary"            

android:textSize="30sp"            

android:hint="hint"             />
        <Button            

android:id="@+id/button2"            

android:layout_width="wrap_content"            

android:layout_height="wrap_content"            

android:text="Button"            

android:onClick="@{()->viewModel.buttonClick()}"            

android:layout_marginTop="36dp"            />
    </LinearLayout>

</LinearLayout>
</layout>

MainActivity.java

package com.app.testapp;

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 android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

import com.app.testapp.databinding.ActivityMainBinding;

public class MainActivity extends AppCompatActivity {

    UserProfileViewModel userProfileViewModel;
    TextView textView;
//    Button button2;
    @Override    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
//        setContentView(R.layout.activity_main);
        userProfileViewModel = ViewModelProviders.of(MainActivity.this).get(UserProfileViewModel.class);

        ActivityMainBinding binding = DataBindingUtil.setContentView(this, R.layout.activity_main);
        binding.setViewModel(userProfileViewModel);
        binding.setLifecycleOwner(this);
        setContentView(binding.getRoot());

        textView = (TextView) findViewById(R.id.textView);
//        button2 = (Button)findViewById(R.id.button2);

//        String s = userProfileViewModel.user.name + "\n" + userProfileViewModel.user.company;//        textView.setText(s);
//        button2.setOnClickListener(new View.OnClickListener() {//            @Override//            public void onClick(View v) {//////                userProfileViewModel.getUser().setValue(new User("ABC", "XYZ"));////                userProfileViewModel.user.company = "XYZ";//            }//        });

//        "abc".toLowerCase()
        userProfileViewModel.getUser().observe(this, new Observer<User>() {
                    @Override                    public void onChanged(@Nullable User user) {
                        textView.setText(user.name);
                    }
                }
        );

    }


}

UserProfileViewModel.Java

package com.app.testapp;

import android.arch.lifecycle.LiveData;
import android.arch.lifecycle.MutableLiveData;
import android.arch.lifecycle.ViewModel;
import android.widget.Toast;

public class UserProfileViewModel extends ViewModel {

//    User user = new User("No Name", "No Com");
    private MutableLiveData<User> user = new MutableLiveData<User>();
    LiveData<User> userLiveData;

    public MutableLiveData<User> getUser() {
        return user;
    }

    public void buttonClick(){
        getUser().setValue(new User("ABC", "XYZ"));
    }
}


User.java

package com.app.testapp;

public class User {

    String name;
    String company;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getCompany() {
        return company;
    }

    public void setCompany(String company) {
        this.company = company;
    }

    public User(String name, String company) {
        this.name = name;
        this.company = company;
    }

}

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