Android Basics Nanodegree By Google

// Report Card class
package com.example.android.reportcard;

public class ReportCard {

    //  @mName stores the name of the student.
    //  @mClassYear stores the student's class graduation year.
    //  @mHistory stores the students grade for history.
    //  @mMath stores the students grade for math.
    //  @mEnglish stores the students grade for english.
    //  @mScience stores the students grade for science.
    private String mName;
    private int mClassYear;
    private int mHistory;
    private int mMath;
    private int mEnglish;
    private int mScience;

    private void reportCard(String name, int classYear, int history, int math, int english, int science) {
        mName = name;
        mClassYear = classYear;
        mHistory = history;
        mMath = math;
        mEnglish = english;
        mScience = science;
    }

    @Override
    // Create report card summary.
    public String toString() {
        String mReportCardSummary;
        mReportCardSummary = 'Report Card Summary:';
        mReportCardSummary += '\nStudent Name: ' + mName;
        mReportCardSummary += '\nClass Year: ' + mClassYear;
        mReportCardSummary += '\nHistory Grade: ' + mHistory;
        mReportCardSummary += '\nMath Grade: ' + mMath;
        mReportCardSummary += '\nEnglish Grade: ' + mEnglish;
        mReportCardSummary += '\nScience Grade: ' + mScience;
        mReportCardSummary += '\nSee you next year!';
        return mReportCardSummary;
    }

    // Get name of student
    public String getName() {
        return mName;
    }

    // Set name of student
    public void setName(String name) {
        mName = name;
    }

    // Get class year
    public int getClassYear() {
        return mClassYear;
    }

    // Set class year
    public void setClassYear(int classYear) {
        mClassYear = classYear;
    }

    // Get history grade
    public int getHistoryGrade() {
        return mHistory;
    }

    // Set history grade
    public void setHistoryGrade(int history) {
        mHistory = history;
    }

    // Get math grade
    public int getMathGrade() {
        return mMath;
    }

    // Set math grade
    public void setMathGrade(int math) {
        mMath = math;
    }

    // Get english grade
    public int getEnglishGrade() {
        return mEnglish;
    }

    // Set english grade
    public void setEnglishGrade(int english) {
        mEnglish = english;
    }

    // Get science grade
    public int getScienceGrade() {
        return mScience;
    }

    // Set science grade
    public void setScienceGrade(int science) {
        mScience = science;
    }
}

package com.example.android.habittracker;

import android.content.ContentValues;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.widget.Toast;

import com.example.android.habittracker.data.HabitContract.HabitEntry;
import com.example.android.habittracker.data.HabitDbHelper;

public class MainActivity extends AppCompatActivity {

    // Reference to the current active HabitDbHelper Instance.
    private HabitDbHelper mDbHelper;

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

        // Create and Grab a referene to the new HabitDbHelper instance.
        mDbHelper = new HabitDbHelper(this);

        // Insert a Habit into the habits Table.
        insertHabit();

        // Read the list of habits stored in the habits Table.
        // Show the result of the query in a simple TextView in the middle of the screen.
        readDatabaseInfo();
    }

    // Insert a Habit into the habits Table.
    private void insertHabit() {

        // Obtain access to the database.
        SQLiteDatabase db = mDbHelper.getWritableDatabase();

        // Create a set of values to add to the database.
        ContentValues values = new ContentValues();

        // The Status of the Habit the user wants to track.
        // 0 = INCOMPLETE (Default 0) and 1 = COMPLETE.
        int status = 0;

        // Add a Name value for the name of the Habit the user wants to track.
        values.put(HabitEntry.COLUMN_HABIT_NAME, 'Walk The Dog');

        // Add a Status value for the status  of the Habit the user wants to track.
        values.put(HabitEntry.COLUMN_HABIT_STATUS, status);

        // Insert the values into the habits Table.
        // Save the result to a variable.
        long newRowId = db.insert(HabitEntry.TABLE_NAME, null, values);

        // If the insertion failed...
        if (newRowId == -1) {

            // Show an error message
            Toast.makeText(getApplicationContext(), 'Error with saving Habit',
                    Toast.LENGTH_SHORT).show();

        } else {

            // Otherwise show a message that the insertion was successful
            // with a reference to the row id.
            Toast.makeText(getApplicationContext(), 'Habit saved with id: '
                    + newRowId, Toast.LENGTH_SHORT).show();
        }
    }

    // Read the list of habits stored in the habits Table.
    private void readDatabaseInfo() {

        // Queries the database and returns a Cursor object.
        Cursor cursor = queryDatabase();

        // Get the indexes of each Column included in the query.
        int idColumnIndex = cursor.getColumnIndex(HabitEntry._ID);
        int nameColumnIndex = cursor.getColumnIndex(HabitEntry.COLUMN_HABIT_NAME);
        int statusColumnIndex = cursor.getColumnIndex(HabitEntry.COLUMN_HABIT_STATUS);
        int dateCreatedColumnIndex = cursor.getColumnIndex(HabitEntry.COLUMN_HABIT_DATE_CREATED);

        // Create a log message to display the format of the Columns in the database.
        Log.d('MainActivity', 'ID - Name - Status - Date created \n');

        // Parse the query using the cursor object.
        try {
            while (cursor.moveToNext()) {

                // Save the values of each Column in all Rows of the Table in the Database.
                int currentID = cursor.getInt(idColumnIndex);
                String currentName = cursor.getString(nameColumnIndex);
                int currentStatus = cursor.getInt(statusColumnIndex);
                String currentDateCreated = cursor.getString(dateCreatedColumnIndex);

                // Show and Append the results of the query in a simple log message.
                Log.d("MainActivity", '\n' + currentID + ' - '
                        + currentName + ' - '
                        + currentStatus + ' - '
                        + currentDateCreated);
            }
        } finally {

            // Close the cursor to prevent memory leaks.
            cursor.close();
        }
    }

    // Queries the database and returns a Cursor object.
    private Cursor queryDatabase() {

        // Obtain access to the database.
        SQLiteDatabase db = mDbHelper.getReadableDatabase();

        // Create a string array of the Columns to be included in the query.
        String[] projection = {
                HabitEntry._ID,
                HabitEntry.COLUMN_HABIT_NAME,
                HabitEntry.COLUMN_HABIT_STATUS,
                HabitEntry.COLUMN_HABIT_DATE_CREATED,
        };

        // Make the query to the database for the specified Columns and return a Cursor.
        return db.query(
                HabitEntry.TABLE_NAME,
                projection,
                null,
                null,
                null, null,
                null);
    }
}

package com.example.android.habittracker.data;

import android.provider.BaseColumns;

public class HabitContract {

    private HabitContract() {
    }

    public static abstract class HabitEntry implements BaseColumns {

        // Name of the Database Table that stores a list of Habits.
        public static final String TABLE_NAME = 'habits';

        // Names of the Columns in the habits Database.
        // Name of the Column that stores the Row ID.
        public static final String _ID = BaseColumns._ID;

        // Name of the Column that stores the Name of the Habit the user wants to track.
        public static final String COLUMN_HABIT_NAME = 'name';

        // Name of the Column that store the Status of the Habit the user wants to track.
        // 0 = INCOMPLETE and 1 = COMPLETE.
        public static final String COLUMN_HABIT_STATUS = 'status';

        // Name of the Column that stores the Date the Habit was added to the Database.
        public static final String COLUMN_HABIT_DATE_CREATED = 'date_created';
    }
}

package com.example.android.habittracker.data;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

public class HabitDbHelper extends SQLiteOpenHelper {

    // The Current Database Version.
    private static final int DATABASE_VERSION = 1;

    // The Current Database Name.
    private static final String DATABASE_NAME = "trackers.db";

    // Constructor for a new HabitDbHelper.
    public HabitDbHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }

    // Creates a new Database named list with a table of habits.
    @Override
    public void onCreate(SQLiteDatabase db) {

        // Create an SQLite command to create a new habits Table and setup the Columns.
        String CREATE_HABITS_TABLE = "CREATE TABLE " + HabitContract.HabitEntry.TABLE_NAME +
                " ("
                + HabitContract.HabitEntry._ID + " INTEGER PRIMARY KEY AUTOINCREMENT,"
                + HabitContract.HabitEntry.COLUMN_HABIT_NAME + " TEXT NOT NULL,"
                + HabitContract.HabitEntry.COLUMN_HABIT_STATUS + " INTEGER NOT NULL DEFAULT 0,"
                + HabitContract.HabitEntry.COLUMN_HABIT_DATE_CREATED
                + " TEXT NOT NULL DEFAULT CURRENT_DATE);";

        // Execute the SQLite command to create the habits Table and setup the Columns.
        db.execSQL(CREATE_HABITS_TABLE);
    }

    // onUpgrade delete the current habits Table and Create a new Table only if...
    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

        // the Database version has been changed.
        if (oldVersion != newVersion) {
            db.execSQL("DROP TABLE IF EXISTS " + HabitContract.HabitEntry.TABLE_NAME);
            onCreate(db);
        }
    }
}