从现有的SQLite数据库显示数据到Listview

Question

I am new to android programming so please help me… I have created mydatabase.sqlite database file using SQLite Database Browser and copy it to assets folder in android application for retrieving data from the database file.

I want to display all the records from the database table on button click and display result in list view.

Here the code

this my databasehelper class

public class DataBaseHelper extends SQLiteOpenHelper 
{ 
private static String TAG = "DataBaseHelper"; // Tag just for the LogCat window 
//destination path (location) of our database on device 
private static String DB_PATH = "";  
private static String DB_NAME ="datacoba";// Database name 
private SQLiteDatabase mDataBase;  
private final Context mContext; 

public DataBaseHelper(Context context)  
{ 
    super(context, DB_NAME, null, 1);// 1? its Database Version 
    DB_PATH = "/data/data/" + context.getPackageName() + "/databases/"; 
    this.mContext = context; 
}    

public void createDataBase() throws IOException 
{ 
    //If database not exists copy it from the assets 

    boolean mDataBaseExist = checkDataBase(); 
    if(!mDataBaseExist) 
    { 
        this.getReadableDatabase(); 
        this.close(); 
        try  
        { 
            //Copy the database from assests 
            copyDataBase(); 
            Log.e(TAG, "createDatabase database created"); 
        }  
        catch (IOException mIOException)  
        { 
            throw new Error("ErrorCopyingDataBase"); 
        } 
    } 
} 
    //Check that the database exists here: /data/data/your package/databases/Da Name 
    private boolean checkDataBase() 
    { 
        File dbFile = new File(DB_PATH + DB_NAME); 
        //Log.v("dbFile", dbFile + "   "+ dbFile.exists()); 
        return dbFile.exists(); 
    } 

    //Copy the database from assets 
    private void copyDataBase() throws IOException 
    { 
        InputStream mInput = mContext.getAssets().open(DB_NAME); 
        String outFileName = DB_PATH + DB_NAME; 
        OutputStream mOutput = new FileOutputStream(outFileName); 
        byte[] mBuffer = new byte[1024]; 
        int mLength; 
        while ((mLength = mInput.read(mBuffer))>0) 
        { 
            mOutput.write(mBuffer, 0, mLength); 
        } 
        mOutput.flush(); 
        mOutput.close(); 
        mInput.close(); 
    } 

    //Open the database, so we can query it 
    public boolean openDataBase() throws SQLException 
    { 
        String mPath = DB_PATH + DB_NAME; 
        //Log.v("mPath", mPath); 
        mDataBase = SQLiteDatabase.openDatabase(mPath, null, SQLiteDatabase.CREATE_IF_NECESSARY); 
        //mDataBase = SQLiteDatabase.openDatabase(mPath, null, SQLiteDatabase.NO_LOCALIZED_COLLATORS); 
        return mDataBase != null; 
    } 

    @Override 
    public synchronized void close()  
    { 
        if(mDataBase != null) 
            mDataBase.close(); 
        super.close(); 
    }

    @Override
    public void onCreate(SQLiteDatabase arg0) {
        // TODO Auto-generated method stub

    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        // TODO Auto-generated method stub

    } 

} 

this Utility Class

public class Utility {

    public static String GetColumnValue(Cursor cur, String ColumnName) {
        try {
            return cur.getString(cur.getColumnIndex(ColumnName));
        } catch (Exception ex) {
            return "";
        }
    }


    public static void ShowMessageBox(Context cont, String msg) {
        Toast toast = Toast.makeText(cont, msg, Toast.LENGTH_SHORT);
        // toast.setGravity(Gravity.CENTER, 0, 0);
        toast.setGravity(Gravity.CENTER | Gravity.CENTER, 0, 0);
        toast.show();
    }
}

This Adapter Class

public class TestAdapter  
{ 
protected static final String TAG = "DataAdapter"; 

private final Context mContext; 
private SQLiteDatabase mDb; 
private DataBaseHelper mDbHelper; 

public TestAdapter(Context context)  
{ 
    this.mContext = context; 
    mDbHelper = new DataBaseHelper(mContext); 
} 

public TestAdapter createDatabase() throws SQLException  
{ 
    try  
    { 
        mDbHelper.createDataBase(); 
    }  
    catch (IOException mIOException)  
    { 
        Log.e(TAG, mIOException.toString() + "  UnableToCreateDatabase"); 
        throw new Error("UnableToCreateDatabase"); 
    } 
    return this; 
} 

public TestAdapter open() throws SQLException  
{ 
    try  
    { 
        mDbHelper.openDataBase(); 
        mDbHelper.close(); 
        mDb = mDbHelper.getReadableDatabase(); 
    }  
    catch (SQLException mSQLException)  
    { 
        Log.e(TAG, "open >>"+ mSQLException.toString()); 
        throw mSQLException; 
    } 
    return this; 
} 

public void close()  
{ 
    mDbHelper.close(); 
} 

 public Cursor getTestData() 
 { 
     try 
     { 
         String sql ="SELECT Nama_student From Nama"; 

         Cursor mCur = mDb.rawQuery(sql, null); 
         if (mCur!=null) 
         { 
            mCur.moveToNext(); 
         } 
         return mCur; 
     } 
     catch (SQLException mSQLException)  
     { 
         Log.e(TAG, "getTestData >>"+ mSQLException.toString()); 
         throw mSQLException; 
     } 
 }

}

and this is my MainActivity Class

public class MainActivity extends Activity {

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

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}



public void LoadEmployee(View v)
{
    TestAdapter mDbHelper = new TestAdapter(this);         
    mDbHelper.createDatabase();       
    mDbHelper.open(); 

    Cursor testdata = mDbHelper.getTestData(); 

    String name = Utility.GetColumnValue(testdata, "Nama_student");


    Utility.ShowMessageBox(this, "Name: "+ name);
    mDbHelper.close();

}

}

The codes produces the output shown by toast, like this And just showed only the first row of the table. How can i display all rows from the table and show result in listview ? EDIT: This my xml layout

<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"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity" >


    <Button
        android:id="@+id/btnSearch"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="14dp"
        android:layout_marginTop="19dp"
        android:onClick="LoadEmployee"
        android:text="Load Employee"
       />
    <ListView
        android:id="@+id/listView1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/btnSearch"
        android:layout_below="@+id/btnSearch"
        android:layout_marginLeft="21dp"
        android:layout_marginTop="166dp" >
    </ListView>

Answer 1

I do not see some ListView in your code. You need ListView and some adapter for it. Then, fill adapter with records from database and set this adapter to your ListView .

Why you return Cursor in your getTestData method? You can for example create some wrapper class and returns List with instances of this class. Via this List is very simple to create adapter for ListView .

Edit:

Ok, first you need to create an ArrayAdapter . You can use some other type of adapter, of course. Or you can create your custom adapter. This way is very simple.

    ArrayAdapter<String> adapter = new ArrayAdapter<String>(context, android.R.layout.simple_list_item_1, list);

List is instance of some list, which contains data you want to display in ListView . Next, you simply initialize ListView and set the adapter.

   listView.setAdapter(adapter);

Answer 2

You'll need to write the following code in your LoadEmployee method:

Cursor testdata = mDbHelper.getTestData();     

 /** the desired columns to be bound **/
 String[] columns = new String[] { "Nama_student" };

 /** the XML defined views which the data will be bound to **/
 int[] to = new int[] { R.id.name_entry, R.id.number_entry };

 /** create the adapter using the cursor pointing to the desired data as well as the layout information **/
 SimpleCursorAdapter mAdapter = new SimpleCursorAdapter(this,
            R.layout.list_example_entry, cursor, columns, to);

 /** set this adapter as your ListActivity's adapter **/
 listview.setAdapter(mAdapter);

The following links will help you understand how it all works:

http://developer.android.com/guide/topics/ui/layout/listview.html

http://www.vogella.com/tutorials/AndroidSQLite/article.html

http://www.tuicool.com/articles/rUFr2m