android - 单击列表中的项目 - 将数据传递给另一个 Activity 并使用 sqlite 数据库显示其他列

Question

我在这里搜索了很多，但没有找到适合我的应用程序的东西。

我有 3 个 Activity ( Activity 1、 Activity 2 和 Activity 3)。

Activity 1 是从我的数据库中填充的 ListView

Activity 2 是从我数据库中的另一个表填充的 ListView (关于我在 Activity 1 中选择的项目)。

Activity 3 是一个 TextView ，我们可以在其中找到 Activity 2 中所选项目的描述。

我的问题是我可以获得所选项目的 ID，但我需要显示其他列的值。

Activity 2 代码:

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));
    }   
}

Activity 3 代码:

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);


}

书单助手

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));
    }

}感谢您的帮助，如果您需要更多信息，请不要犹豫。

Answer 1

我不完全理解你的问题，但我认为你想传递的不仅仅是 ID 到 Activity 3，

好吧，您可以将正在使用的整个对象作为可序列化项传递，

只需实现Serializable(class xxx implement Serializable)，就可以了，

intent.putExtra("key", object);

在 Activity 3中

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

希望这对您有所帮助，否则如果我不是您所需要的，请向我们提供更多信息，