java - 安卓 SQLite : Data being added again and again

Question

如果我在 EditText 中键入 1234，MainActivity 中的 ListView 显示为: 1个 12 123 1234 而不仅仅是 1234。

主要 Activity :

public class MainActivity extends AppCompatActivity {

ListView notesListView;
static ArrayList<String> notesArrayList;
static ArrayAdapter<String> adapter;


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

    notesListView = (ListView) findViewById(R.id.notesListView);
    notesArrayList = new ArrayList<String>();

    Main2Activity.myDb = new DatabaseOperations(this);

    if (Main2Activity.myDb != null) {
        notesArrayList.clear();
        Cursor result = Main2Activity.myDb.getData();
        if (result.getCount() == 0) {
            Log.i("Error", "error");
            return;
        }
        while (result.moveToNext()) {
            notesArrayList.add(result.getString(result.getColumnIndex("text")));
        }
    }

    //notesArrayList.add("Akhilesh Chobey");
    adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, notesArrayList);
    notesListView.setAdapter(adapter);

    notesListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
            Intent intent = new Intent(getApplicationContext(), Main2Activity.class);
            intent.putExtra("notePosition", i);
            startActivity(intent);
        }
    });

    notesListView.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
        @Override
        public boolean onItemLongClick(AdapterView<?> adapterView, View view, int i, long l) {


            return false;
        }
    });
}

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

@Override
public boolean onOptionsItemSelected(MenuItem item) {

    int id = item.getItemId();
    if (id == R.id.add_button) {
        notesArrayList.add("");
    }
    Intent intent = new Intent(getApplicationContext(), Main2Activity.class);
    intent.putExtra("notePosition", notesArrayList.size() - 1);
    startActivity(intent);


    return true;

}

Main2Activity(EditText Activity ):

public class Main2Activity extends AppCompatActivity implements TextWatcher {

static DatabaseOperations myDb;
EditText editNote;
int position;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main2);
    editNote = (EditText) findViewById(R.id.noteEditText);

    myDb = new DatabaseOperations(Main2Activity.this);

    Intent intent = getIntent();
    position = intent.getIntExtra("notePosition", -1);
    if(position != -1){

        editNote.setText(MainActivity.notesArrayList.get(position));

    }
    editNote.addTextChangedListener(this);
}

@Override
public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {

}

@Override
public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {
    if (myDb != null) {
        boolean isInserted = myDb.insertData(editNote.getText().toString());
        MainActivity.notesArrayList.set(position, String.valueOf(charSequence));
        MainActivity.adapter.notifyDataSetChanged();
    }

}

数据库助手类:

public class DatabaseOperations extends SQLiteOpenHelper {

    public static final String DatabaseName = "notes.db";
    public static final String TableName = "notes";
    public static final String Col1 = "text";

    public DatabaseOperations(Context context) {
        super(context, DatabaseName, null, 1);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL("create table " + TableName + " (text TEXT PRIMARY KEY) ");
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int i, int i1) {

        db.execSQL("DROP TABLE IF EXISTS " + TableName);
        //onCreate(db);

    }

    public boolean insertData(String note){

        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues contentValues = new ContentValues();
        contentValues.put(Col1, note);

        long result = db.insert(TableName, null, contentValues);
        if(result == -1){
            return false;
        }else {
            return true;
        }
    }

    public Cursor getData(){
        SQLiteDatabase db = this.getWritableDatabase();
        Cursor result = db.rawQuery("select * from " + TableName, null);
        return result;
    }
}

Answer 1

发生这种情况是因为您在 onTextChanged() 期间插入了 EditText 的内容。这意味着每次文本更改时，都会创建一个新的数据库条目。

我建议添加一个确认内容为数据库条目的按钮。