<resources> 
    <color name="colorPrimary">#0F9D58</color> 
    <color name="colorPrimaryDark">#16E37F</color> 
    <color name="colorAccent">#03DAC5</color> 
</resources> 

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <Button
        android:id="@+id/saveBtn"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/inputField"
        android:layout_centerInParent="true"
        android:layout_margin="8dp"
        android:background="@color/colorPrimary"
        android:text="Save"
        android:textColor="#ffffff" />

    <Button
        android:id="@+id/getBtn"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/outputField"
        android:layout_centerInParent="true"
        android:layout_margin="8dp"
        android:background="@color/colorPrimary"
        android:text="Show"
        android:textColor="#ffffff" />

    <!--For input we have used EditText-->
    <EditText
        android:id="@+id/inputField"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="8dp"
        android:hint="Input Data"
        android:textAlignment="center" />

    <!--For output we have used TextView-->
    <TextView
        android:id="@+id/outputField"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/saveBtn"
        android:layout_margin="8dp"
        android:hint="Output Data"
        android:textAlignment="center" />

</RelativeLayout>

import android.content.Context;
import android.content.SharedPreferences;
import android.preference.PreferenceManager;
import javax.inject.Singleton;
import dagger.Module;
import dagger.Provides;

// @Module annotation is used over the class that 
// creates construct object and provides dependencies
@Module
public class SharedPreferenceModule {
    private Context context;

    // Context gets initialize from the constructor itself
    public SharedPreferenceModule(Context context) {
        this.context = context;
    }

    @Singleton
    @Provides
    public Context provideContext() {
        return context;
    }

    // @Singleton indicates that only single instance 
    // of dependency object is created
    // @Provide annotations used over the methods that
    // will provides the object of module class
    // This method will return the dependent object
    @Singleton
    @Provides
    public SharedPreferences provideSharedPreferences(Context context) {
        return PreferenceManager.getDefaultSharedPreferences(context);
    }
}

import javax.inject.Singleton;
import dagger.Component;

// All the modules are mentioned under 
// the @Component annotation
@Singleton
@Component(modules = {SharedPreferenceModule.class})
public interface SharedPreferenceComponent {
    void inject(MainActivity mainActivity);
}

import android.content.SharedPreferences;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import androidx.appcompat.app.AppCompatActivity;
import javax.inject.Inject;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

    EditText editText;
    TextView textView;
    Button saveBtn, getBtn;
    private SharedPreferenceComponent sharedPreferenceComponent;

    // @Inject is used to tell which activity, 
    // fragment or service is allowed to request
    // dependencies declared in Module class
    @Inject
    SharedPreferences sharedPreferences;

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

        // Referencing the EditText, TextView and Buttons
        editText = (EditText) findViewById(R.id.inputField);
        textView = (TextView) findViewById(R.id.outputField);
        saveBtn = (Button) findViewById(R.id.saveBtn);
        getBtn = (Button) findViewById(R.id.getBtn);

        // Setting onClickListener behavior on button to reference
        // to the current activity(this MainActivity)
        saveBtn.setOnClickListener(this);
        getBtn.setOnClickListener(this);

        // Here we are binding dagger to our application
        // Dagger keyword will be prefix to the component name
        sharedPreferenceComponent = DaggerSharedPreferenceComponent.builder().sharedPreferenceModule(
                new SharedPreferenceModule(this)).build();

        // we are injecting the shared preference dependent object
        sharedPreferenceComponent.inject(this);
    }

    @Override
    public void onClick(View view) {
        switch (view.getId()) {
            case R.id.saveBtn:
                // Saving data to shared preference
                // inputField acts as key and editText data as value to that key
                SharedPreferences.Editor editor = sharedPreferences.edit();
                editor.putString("inputField", editText.getText().toString().trim());
                editor.apply();
                break;
            case R.id.getBtn:
                // getting shared preferences data and set it to textview
                // s1: is the default string, You can write any thing there or leave it
                textView.setText(sharedPreferences.getString("inputField", ""));
                break;
        }
    }
}