Question

当我点击下拉选项时，我有一个下拉列表，然后它将点击数据库并将数据检索到我的另一个下拉列表。对于ex，我有一个下拉列表，其中类名作为选项，当我点击类名时，它会将该类的学生名称从数据库中检索到另一个下拉列表中。在点击提交按钮后将这些细节发送到数据库？

Answer 1

我曾经基于这个例子实现了基于另一个微调器选择

填充微调器的代码

http://www.javaknowledge.info/populate-second-spinner-based-on-selection-of-first-spinner/

并且从sqlite数据库填充微调器我使用了这个示例...请检查此链接

http://instinctcoder.com/android-studio-spinner-populate-data-sqlite/

我的问题已解决

Answer 2

//DATABASE HANdler.java

public class DatabaseHandler extends SQLiteOpenHelper {
    // Database Version
    private static final int DATABASE_VERSION = 1;

    // Database Name
    private static final String DATABASE_NAME = "spinnerExample";

    // Labels table name
    private static final String TABLE_LABELS = "labels";

    // Labels Table Columns names
    private static final String KEY_ID = "id";
    private static final String KEY_NAME = "name";

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

    // Creating Tables
    @Override
    public void onCreate(SQLiteDatabase db) {
        // Category table create query
        String CREATE_CATEGORIES_TABLE = "CREATE TABLE " + TABLE_LABELS + "("
                + KEY_ID + " INTEGER PRIMARY KEY," + KEY_NAME + " TEXT)";
        db.execSQL(CREATE_CATEGORIES_TABLE);
    }

    // Upgrading database
    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        // Drop older table if existed
        db.execSQL("DROP TABLE IF EXISTS " + TABLE_LABELS);

        // Create tables again
        onCreate(db);
    }

    /**
     * Inserting new lable into lables table
     * */
    public void insertLabel(String label){
        SQLiteDatabase db = this.getWritableDatabase();

        ContentValues values = new ContentValues();
        values.put(KEY_NAME, label);

        // Inserting Row
        db.insert(TABLE_LABELS, null, values);
        db.close(); // Closing database connection
    }

    /**
     * Getting all labels
     * returns list of labels
     * */
    public List<String> getAllLabels(){
        List<String> labels = new ArrayList<String>();

        // Select All Query
        String selectQuery = "SELECT  * FROM " + TABLE_LABELS;

        SQLiteDatabase db = this.getReadableDatabase();
        Cursor cursor = db.rawQuery(selectQuery, null);

        // looping through all rows and adding to list
        if (cursor.moveToFirst()) {
            do {
                labels.add(cursor.getString(1));
            } while (cursor.moveToNext());
        }

        // closing connection
        cursor.close();
        db.close();

        // returning lables
        return labels;
    }
}

//In your Main Acticity ,my one is AndroidSpinnerFromSQLiteActivity

public class AndroidSpinnerFromSQLiteActivity extends Activity implements
        OnItemSelectedListener {

    // Spinner element
    Spinner spinner;

    // Add button
    Button btnAdd;

    // Input text
    EditText inputLabel;

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

        // Spinner element
        spinner = (Spinner) findViewById(R.id.spinner);

        // add button
        btnAdd = (Button) findViewById(R.id.btn_add);

        // new label input field
        inputLabel = (EditText) findViewById(R.id.input_label);

        // Spinner click listener
        spinner.setOnItemSelectedListener(this);

        // Loading spinner data from database
        loadSpinnerData();

        /**
         * Add new label button click listener
         * */
        btnAdd.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View arg0) {
                String label = inputLabel.getText().toString();

                if (label.trim().length() > 0) {
                    // database handler
                    DatabaseHandler db = new DatabaseHandler(
                            getApplicationContext());

                    // inserting new label into database
                    db.insertLabel(label);

                    // making input filed text to blank
                    inputLabel.setText("");

                    // Hiding the keyboard
                    InputMethodManager imm = (InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE);
                    imm.hideSoftInputFromWindow(inputLabel.getWindowToken(), 0);

                    // loading spinner with newly added data
                    loadSpinnerData();
                } else {
                    Toast.makeText(getApplicationContext(), "Please enter label name",
                            Toast.LENGTH_SHORT).show();
                }

            }
        });
    }

    /**
     * Function to load the spinner data from SQLite database
     * */
    private void loadSpinnerData() {
        // database handler
        DatabaseHandler db = new DatabaseHandler(getApplicationContext());

        // Spinner Drop down elements
        List<String> lables = db.getAllLabels();

        // Creating adapter for spinner
        ArrayAdapter<String> dataAdapter = new ArrayAdapter<String>(this,
                android.R.layout.simple_spinner_item, lables);

        // Drop down layout style - list view with radio button
        dataAdapter
                .setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);

        // attaching data adapter to spinner
        spinner.setAdapter(dataAdapter);
    }

    @Override
    public void onItemSelected(AdapterView<?> parent, View view, int position,
            long id) {
        // On selecting a spinner item
        String label = parent.getItemAtPosition(position).toString();

        // Showing selected spinner item
        Toast.makeText(parent.getContext(), "You selected: " + label,
                Toast.LENGTH_LONG).show();

    }

    @Override
    public void onNothingSelected(AdapterView<?> arg0) {
        // TODO Auto-generated method stub

    }
}

如何从数据库中获取名称到android中的下拉列表？

2 个答案: