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Manipulation d'une base de données SQLite


La vidéo présentant cet exemple de code

Implémentation de la classe DatabaseManager

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package fr.koor.testsqlite;


import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;

import java.util.ArrayList;
import java.util.Date;
import java.util.List;

public class DatabaseManager extends SQLiteOpenHelper {

    private static final String DATABASE_NAME = "Game.db";
    private static final int DATABASE_VERSION = 2;

    public DatabaseManager( Context context ) {
        super( context, DATABASE_NAME, null, DATABASE_VERSION );
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        String strSql = "create table T_Scores ("
                      + "    idScore integer primary key autoincrement,"
                      + "    name text not null,"
                      + "    score integer not null,"
                      + "    when_ integer not null"
                      + ")";
        db.execSQL( strSql );
        Log.i( "DATABASE", "onCreate invoked" );
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        //String strSql = "alter table T_Scores add column ...";
        String strSql = "drop table T_Scores";
        db.execSQL( strSql );
        this.onCreate( db );
        Log.i( "DATABASE", "onUpgrade invoked" );
    }

    public void insertScore( String name, int score ) {
        name = name.replace( "'", "''" );
        String strSql = "insert into T_Scores (name, score, when_) values ('"
                      + name + "', " + score + ", " + new Date().getTime() + ")";
        this.getWritableDatabase().execSQL( strSql );
        Log.i( "DATABASE", "insertScore invoked" );
    }

    public List<ScoreData> readTop10() {
        List<ScoreData> scores = new ArrayList<>();

        // 1ère technique : SQL
        //String strSql = "select * from T_Scores order by score desc limit 10";
        //Cursor cursor = this.getReadableDatabase().rawQuery( strSql, null );

        // 2nd technique "plus objet"
        Cursor cursor = this.getReadableDatabase().query( "T_Scores",
                new String[] { "idScore", "name", "score", "when_" },
                null, null, null, null, "score desc", "10" );
        cursor.moveToFirst();
        while( ! cursor.isAfterLast() ) {
            ScoreData score = new ScoreData( cursor.getInt( 0 ), cursor.getString( 1 ),
                    cursor.getInt( 2 ), new Date( cursor.getLong( 3 ) ) );
            scores.add( score );
            cursor.moveToNext();
        }
        cursor.close();

        return scores;
    }

}
Classe DatabaseManager.java

Implémentation de la classe ScoreData

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package fr.koor.testsqlite;

import java.util.Date;


public class ScoreData {

    private int idScore;
    private String name;
    private int score;
    private Date when;


    public ScoreData(int idScore, String name, int score, Date when) {
        this.setIdScore( idScore );
        this.setName( name );
        this.setScore( score );
        this.setWhen( when );
    }

    public int getIdScore() {
        return idScore;
    }

    public void setIdScore(int idScore) {
        this.idScore = idScore;
    }

    public String getName() {
        return name;
    }

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

    public int getScore() {
        return score;
    }

    public void setScore(int score) {
        this.score = score;
    }

    public Date getWhen() {
        return when;
    }

    public void setWhen(Date when) {
        this.when = when;
    }

    @Override
    public String toString() {
        return idScore + ": " + name + " -> " + score + " at " + when.toString();
    }
}
Classe ScoreData.java

Exemple d'utilisation de la classe DatabaseManager

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package fr.koor.testsqlite;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.TextView;

import java.util.List;

public class MainActivity extends AppCompatActivity {

    private TextView scoresView;
    private DatabaseManager databaseManager;


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

        scoresView = (TextView) findViewById( R.id.scoresView );
        databaseManager = new DatabaseManager( this );

        databaseManager.insertScore( "Alexandre", 800 );
//        databaseManager.insertScore( "Christelle", 530 );
//        databaseManager.insertScore( "Dominique", 50 );
//        databaseManager.insertScore( "Aurélie", 100 );
//        databaseManager.insertScore( "Guillaume", 980 );

        List<ScoreData> scores = databaseManager.readTop10();
        for ( ScoreData score : scores ) {
            scoresView.append( score.toString() + "\n\n" );
        }

        databaseManager.close();
    }
}
Classe MainActivity.java