单击列表中的项目-将数据传递到另一个活动，并使用sqlite数据库显示其他列

Question

I search a lot here but i didn't find something working on my app.

I have 3 Activity (Activity 1, Activity 2 and Activity 3).

Activity 1 is a list view populated from my database

Activity 2 is a list view populated from another table on my database(regarding the item selected in my activity 1).

Activity 3 is a text view where we can find a description of the selected item in the activity 2.

My problem is that i can get the ID of the selected item but i need to show value of other columns.

Activity 2 code :

public final static String ID_EXTRA="com.example.testdb5._ID";

String passedVar=null;
private TextView passedView=null;
private BooklistHelper dbBookHelper = null;
private Cursor ourCursor = null;
private BookAdapter adapter=null;




public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.act2);

    passedVar=getIntent().getStringExtra(Tutorial16.ID_EXTRA);

    ListView myListView = (ListView)findViewById(R.id.myListView);

    dbBookHelper=new BooklistHelper(this);

    ourCursor=dbBookHelper.getBooksByAuthor(passedVar);

    startManagingCursor(ourCursor);

    adapter=new BookAdapter(ourCursor);

    myListView.setAdapter(adapter);

    myListView.setOnItemClickListener(onListClick);

}

private AdapterView.OnItemClickListener onListClick=new AdapterView.OnItemClickListener() {
    public void onItemClick(AdapterView<?> parent, 
            View view, int position,
            long id)
    {
        Intent i=new Intent(Activity2.this, Activity3.class);

        i.putExtra(ID_EXTRA, String.valueOf(id));
        startActivity(i);

    }
};


class BookAdapter extends CursorAdapter {
    BookAdapter(Cursor c) {
        super(Activity2.this, c);

    }

    public void bindView(View row, Context ctxt, 
            Cursor c) {
        BookHolder holder=(BookHolder)row.getTag();
        holder.populateFrom(c, dbBookHelper);

    }

    public View newView(Context ctxt, Cursor c, 
            ViewGroup parent) {
        LayoutInflater inflater=getLayoutInflater();
        View row=inflater.inflate(R.layout.row2,  parent, false);
        BookHolder holder=new BookHolder(row);
        row.setTag(holder);
        return(row);
    }


}

static class BookHolder {
    private TextView name=null;

    BookHolder(View row) {
        name=(TextView)row.findViewById(R.id.bookText);
    }

    void populateFrom(Cursor c, BooklistHelper r) {
        name.setText(r.getName(c));
    }   
}

Acitivity 3 code :

public class Activity3 extends Activity{

String passedVar=null;
private TextView passedView=null;

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.act3);

    passedVar=getIntent().getStringExtra(Activity2.ID_EXTRA);

    passedView=(TextView)findViewById(R.id.passed);

    passedView.setText("You Clicked item Id="+passedVar);


}

BooklistHelper

public class BooklistHelper extends SQLiteOpenHelper{

//The Android's default system path of your application database.
private static String DB_PATH = "/data/data/com.example.testdb5/databases/";
private static String DB_NAME = "booklist.db";
private static final String TABLE_NAME = "Authors";
private static final String COLUMN_ID = "_id";
public static final String COLUMN_TITLE = "author_name";

private static final String SECOND_TABLE_NAME = "Books";
private static final String SECOND_COLUMN_ID = "_id";
public static final String SECOND_COLUMN_TITLE = "book_name";




private SQLiteDatabase myDataBase; 

private final Context myContext;

/**
 * Constructor
 * Takes and keeps a reference of the passed context in order to access to the application assets and resources.
 * @param context
 */
public BooklistHelper(Context context) {

    super(context, DB_NAME, null, 1);
    this.myContext = context;
}   


public void createDataBase() throws IOException{

    boolean dbExist = checkDataBase();

    if(dbExist){
        //do nothing - database already exist
    }else{

        //By calling this method and empty database will be created into the default system path
           //of your application so we are gonna be able to overwrite that database with our database.
        this.getReadableDatabase();

        try {

            copyDataBase();

        } catch (IOException e) {

            throw new Error("Error copying database");

        }
    }

}

/**
 * Check if the database already exist to avoid re-copying the file each time you open the application.
 * @return true if it exists, false if it doesn't
 */
private boolean checkDataBase(){

    SQLiteDatabase checkDB = null;

    try{
        String myPath = DB_PATH + DB_NAME;
        checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);

    }catch(SQLiteException e){

        //database does't exist yet.

    }

    if(checkDB != null){

        checkDB.close();

    }

    return checkDB != null ? true : false;
}

/**
 * Copies your database from your local assets-folder to the just created empty database in the
 * system folder, from where it can be accessed and handled.
 * This is done by transfering bytestream.
 * */
private void copyDataBase() throws IOException{

    //Open your local db as the input stream
    InputStream myInput = myContext.getAssets().open(DB_NAME);

    // Path to the just created empty db
    String outFileName = DB_PATH + DB_NAME;

    //Open the empty db as the output stream
    OutputStream myOutput = new FileOutputStream(outFileName);

    //transfer bytes from the inputfile to the outputfile
    byte[] buffer = new byte[1024];
    int length;
    while ((length = myInput.read(buffer))>0){
        myOutput.write(buffer, 0, length);
    }

    //Close the streams
    myOutput.flush();
    myOutput.close();
    myInput.close();

}

public void openDataBase() throws SQLException{

    //Open the database
    String myPath = DB_PATH + DB_NAME;
    myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);

}

@Override
public synchronized void close() {

        if(myDataBase != null)
            myDataBase.close();

        super.close();

}



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

}

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

}

    // Add your public helper methods to access and get content from the database.
   // You could return cursors by doing "return myDataBase.query(....)" so it'd be easy
   // to you to create adapters for your views.
public Cursor getCursor() {

        SQLiteQueryBuilder queryBuilder = new SQLiteQueryBuilder();

        queryBuilder.setTables(TABLE_NAME);

        String[] asColumnsToReturn = new String [] { COLUMN_ID, COLUMN_TITLE};

        //make sure get search by string pass correctly
        Cursor mCursor = queryBuilder.query(myDataBase, asColumnsToReturn, null, 
                null, null, null, "author_name ASC");



        return mCursor;

    }

    public String getName(Cursor c) {
        return(c.getString(1));

    }

    public Cursor getBooksByAuthor(String id) {
        String[] args={id};

        return(getReadableDatabase()
                .rawQuery("SELECT _id, book_name FROM Books WHERE author_id=?",
                        args));
    }

} Thank you for your help and don't hesitate if you need more information.

Answer 1

I don't fully understand your question, but I think you want to pass more than just the ID to the activity 3,

well you could pass the whole object you are working with as a serializable item,

just implement Serializable ( class xxx implement Serializable ) , and you are good to go,

intent.putExtra("key", object);

in the activity3

yourObjectInstance = (YourObject) getIntent().getSerializableExtra("key");

hope this helps, otherwise if I it's not what you need, please provide us with more infos,

Answer 2

For your first activity, you need to get the data from the database that includes what you want to display in the ListView and any additional data you need to pass to Activity 2, so that Activity 2 has what it needs to get the information from the database.

Activity 2 does the same thing as Activty 1. Get what it needs for display and info to pass to Activity 3.

In that onItemClick(), you need to get the item that was clicked from your ArrayList using the position of that item. The ID of the item clicked is not useful for that. It is not the same thing as the id of the item in the database.

Your question shows a basic lack of understanding of how you would use an ArrayList and a ListView. There are many examples of that on the internet. Just Google "android listview example".

Answer 3

If the other columns are in listView you can get those values:

private AdapterView.OnItemClickListener onListClick=new AdapterView.OnItemClickListener() {
    public void onItemClick(AdapterView<?> parent, 
            View view, int position,
            long id)
    {
        TextView view1 = (TextView)view.findViewById(R.id.yourTextView1);
        TextView view2 = (TextView)view.findViewById(R.id.yourTextView2);
        ....
        .... 

        Intent i=new Intent(Activity2.this, Activity3.class);

        i.putExtra(ID_EXTRA, String.valueOf(id));
        i.putExtra(VALUE1_EXTRA, view1.getText().toString());
        i.putExtra(VALUE2_EXTRA, view2.getText().toString());
        .....
        .....

        startActivity(i);

    }
};

Answer 4

here is another way to retreive data from the data base, adapt it to your needs

public ArrayList<MyObject> getDataById(String mId) {
        String query = "select * from table where id=" + mId;

        ArrayList<MyObject> mObjects = new ArrayList<MyObject>();

        Cursor c = myDataBase.rawQuery(query, null);
        int id = c.getColumnIndex("id");
        int val1 = c.getColumnIndex("val1");
        int val2 = c.getColumnIndex("val2");

        for (c.moveToFirst(); !c.isAfterLast(); c.moveToNext()) {
            MyObject d = new MyObject();
            d.setId(c.getString(id));
            d.setVal1(c.getString(val1));
            d.setVal2(c.getString(val2));

            mObjects .add(d);
        }
        return mObjects ;
    }

so this returns to you an ArrayList of all your data, from here it's fairly easy to manage, hope this helps