private String sharedPrefFile =
	"com.example.android.hellosharedprefs";
mPreferences =
	getSharedPreferences(sharedPrefFile, MODE_PRIVATE);

@Override
protected void onPause() {
   super.onPause();
   SharedPreferences.Editor preferencesEditor =     
       mPreferences.edit();
   preferencesEditor.putInt("count", mCount);
   preferencesEditor.putInt("color", mCurrentColor);
   preferencesEditor.apply();
}

mPreferences = getSharedPreferences(sharedPrefFile, MODE_PRIVATE);
if (savedInstanceState != null) {
    mCount = mPreferences.getInt("count", 1);
    mShowCount.setText(String.format("%s", mCount));

    mCurrentColor = mPreferences.getInt("color", mCurrentColor);
    mShowCount.setBackgroundColor(mCurrentColor);

    mNewText = mPreferences.getString("text", "");
} else { … }

SharedPreferences.Editor preferencesEditor =
              mPreferences.edit();
preferencesEditor.clear();
preferencesEditor.apply();

/*
 * Copyright (C) 2016 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.example.android.hellosharedprefs;

import android.content.SharedPreferences;
import android.graphics.drawable.ColorDrawable;
import android.support.v4.content.ContextCompat;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.TextView;

/**
 * HelloSharedPrefs is an adaptation of the HelloToast app from chapter 1.
 * It includes:
 * - Buttons for changing the background color.
 * - Maintenance of instance state.
 * - Themes and styles.
 * - Read and write shared preferences for the current count and the color.
 * <p>
 * This is the solution code for HelloSharedPrefs.
 */
public class MainActivity extends AppCompatActivity {
    // Current count
    private int mCount = 0;
    // Current background color
    private int mColor;
    // Text view to display both count and color
    private TextView mShowCountTextView;

    // Key for current count
    private final String COUNT_KEY = "count";
    // Key for current color
    private final String COLOR_KEY = "color";

    // Shared preferences object
    private SharedPreferences mPreferences;

    // Name of shared preferences file
    private String sharedPrefFile =
            "com.example.android.hellosharedprefs";


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

        // Initialize views, color, preferences
        mShowCountTextView = findViewById(R.id.count_textview);
        mColor = ContextCompat.getColor(this,
                R.color.default_background);

        mPreferences = getSharedPreferences(sharedPrefFile, MODE_PRIVATE);

        // Restore preferences
        mCount = mPreferences.getInt(COUNT_KEY, 0);
        mShowCountTextView.setText(String.format("%s", mCount));
        mColor = mPreferences.getInt(COLOR_KEY, mColor);
        mShowCountTextView.setBackgroundColor(mColor);
    }

    /**
     * Handles the onClick for the background color buttons.  Gets background
     * color of the button that was clicked, and sets the TextView background
     * to that color.
     *
     * @param view The view (Button) that was clicked.
     */
    public void changeBackground(View view) {
        int color = ((ColorDrawable) view.getBackground()).getColor();
        mShowCountTextView.setBackgroundColor(color);
        mColor = color;
    }

    /**
     * Handles the onClick for the Count button.  Increments the value of the
     * mCount global and updates the TextView.
     *
     * @param view The view (Button) that was clicked.
     */
    public void countUp(View view) {
        mCount++;
        mShowCountTextView.setText(String.format("%s", mCount));
    }

    /**
     * Handles the onClick for the Reset button.  Resets the global count and
     * background variables to the defaults and resets the views to those
     * default values.
     *
     * @param view The view (Button) that was clicked.
     */
    public void reset(View view) {
        // Reset count
        mCount = 0;
        mShowCountTextView.setText(String.format("%s", mCount));

        // Reset color
        mColor = ContextCompat.getColor(this,
                R.color.default_background);
        mShowCountTextView.setBackgroundColor(mColor);

        // Clear preferences
        SharedPreferences.Editor preferencesEditor = mPreferences.edit();
        preferencesEditor.clear();
        preferencesEditor.apply();
    }

    /**
     * Callback for activity pause.  Shared preferences are saved here.
     */
    @Override
    protected void onPause() {
        super.onPause();

        SharedPreferences.Editor preferencesEditor = mPreferences.edit();
        preferencesEditor.putInt(COUNT_KEY, mCount);
        preferencesEditor.putInt(COLOR_KEY, mColor);
        preferencesEditor.apply();
    }
}