安卓 SQLite : Failing to update records

Question

我正在开发一个小型应用程序，用于记录地点及其所属的类别。现在，我只处理类别表，一旦我成功执行了所有 CRUD 操作，我就会继续处理应用程序的其余部分。

问题是，我设法插入、删除和读取该表，但我无法更新。我有这段代码:

数据库适配器:

...
    public boolean updateCategory(long rowId, String name) {
        ContentValues args = new ContentValues();
        args.put(KEY_ID_CAT, rowId);
        args.put(KEY_NAME_CAT, name);
        return db.update(TABLE_CATEGORY, args, KEY_ROWID_CAT + "=" + rowId, null) > 0;
    }
...

---

我的 EditCategory 类:

public class S7_EditCategory extends Activity {

    EditText et_name_category;
    private Context ctx;
    int duration = Toast.LENGTH_SHORT;

    @Override
    public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.s7_edit_categories);

        et_name_category = (EditText) findViewById(R.id.edit_category);
        ctx = this;

        final String nome = getIntent().getStringExtra("nome");
        final long id_cat = getIntent().getIntExtra("_id", 0);

        et_nome_category.setText(nome);

        Button button_save = (Button) findViewById(R.id.button3);

        button_save.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {

                try {

                    String new_cat = et_name_category.getText().toString();
                    DBAdapter dbadap = DBAdapter.getInstance(ctx);
                    dbadap.updateCategory(id_cat, new_cat);

                    Intent i = new Intent(ctx, S5_Categories.class);
                    setResult(RESULT_OK, i);
                    finish();

                    }

                    catch (Exception ex) {

                        throw new Error("some error");
                    }
                }
            });

        }
    }

Logcat 告诉我 ( _id = 0 ) 所以，我认为它与从上一个 Activity Category 传递的参数有关:

public class S5_Categories extends ListActivity {

    private Context ctx;
    private SimpleCursorAdapter adapter;

    public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.s5_categorias);
        ctx = this;

        fillList();         
        getListView().setOnItemClickListener(new OnItemClickListener() {

            @Override
            public void onItemClick(AdapterView<?> parentView, View view, int position, long id) {

                Cursor c = (Cursor) parentView.getItemAtPosition(position);

                Intent i = new Intent(ctx, S7_EditCategoria.class); 
                i.putExtra("nome", c.getString(c.getColumnIndexOrThrow("nome")));
                i.putExtra("id_cat", c.getColumnIndex("_id") + 1);
                startActivityForResult(i, 0);

            }
        });
    }

    private void fillList() {
        try {

            DBAdapter dbadap = DBAdapter.getInstance(ctx);
            Cursor c = dbadap.getAllCategorias();

            String[] from = new String[] { "nome" };
            int[] to = new int[] { android.R.id.text1 };

            adapter = new SimpleCursorAdapter(this,
                    android.R.layout.simple_list_item_1, c, from, to,
                    SimpleCursorAdapter.FLAG_REGISTER_CONTENT_OBSERVER);

            adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
            setListAdapter(adapter);
        }

        catch (Exception ex) {

            throw new Error(ex.getMessage());
        }
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {

        super.onActivityResult(requestCode, resultCode, data);

        switch(requestCode) {

        case 0:
            if (data != null) {

                DBAdapter dbadap = DBAdapter.getInstance(ctx);
                Cursor cursor = dbadap.getAllCategorias();
                adapter.changeCursor(cursor);

            }
        }
    }
}

好吧，有人可以帮我吗？提前致谢恰帕

---

好的，现在我设法获得了那个参数 id，但是我在更新时仍然遇到错误:当我尝试时，我得到这样的错误:

使用 UPDATE category SET name=?, id_cat=? 更新 name=hospitals id_cat=4 时出错其中 id=4

请帮忙

恰帕

Answer 1

试试下面的方法

db.update(TABLE_CATEGORY, args, KEY_ROWID_CAT + "=?", new String[] { (rowId) });

代替

db.update(TABLE_CATEGORY, args, KEY_ROWID_CAT + "=" + rowId, null)

为什么要将它作为 int。他们有什么正当理由。我没有从您提供的代码中找到任何原因。如果他们没有正当理由意味着改变你的方法，如下所示。

public boolean updateCategory(long rowId, String name) {
    ContentValues args = new ContentValues();
    args.put(KEY_ID_CAT, rowId);
    args.put(KEY_NAME_CAT, name);
    db.update(TABLE_CATEGORY, args, KEY_ROWID_CAT + "=?", new String[] { (rowId) });
}

希望对您有所帮助。