究竟是什么标识了网站访问者？

Question

Вероника

Asked:2020-01-08 03:40:54 +0000 UTC2020-01-08 03:40:54 +0000 UTC 2020-01-08 03:40:54 +0000 UTC

通过 CursorLoader 的两个游标

772

如何通过 cursorloader 连接两个游标？到目前为止，我有以下内容

public class MainActivity extends AppCompatActivity implements LoaderManager.LoaderCallbacks<Cursor> {

    private AutoCompleteTextView txtSearch;
    private Spinner spinner;
    private ListView list;
    private ImageButton btnClear;

    DBHeler db;

    private MyCursorAdapter cursorAdapter;

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

        db = new DBHeler(this);

        try {
            db.createDataBase();
            db.openDataBase();
        } catch (IOException ex) {
            ex.printStackTrace();
        }

        spinner = (Spinner) findViewById(R.id.spinner);
        // Настраиваем адаптер
        ArrayAdapter<?> adapter =
                ArrayAdapter.createFromResource(this, R.array.types, android.R.layout.simple_spinner_item);
        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        // Вызываем адаптер
        spinner.setAdapter(adapter);

        txtSearch = (AutoCompleteTextView) findViewById(R.id.txtSearch);
        list = (ListView) findViewById(R.id.list);
        btnClear = (ImageButton) findViewById(R.id.btnClear);

        /*Выводим в список все слова, при запуске программы*/
        String selectedItem = spinner.getSelectedItem().toString();
        if (selectedItem.equals("С русского на английский")) {
            cursorAdapter = new MyCursorAdapter(this, R.layout.item, null, 0);
            list.setAdapter(cursorAdapter);
        } else if (selectedItem.equals("С английского на русский")) {
            cursorAdapter = new MyCursorAdapter(this, R.layout.item, null, 0);
            list.setAdapter(cursorAdapter);
        }
    }

    @Override
    protected void onResume() {
        super.onResume();

        txtSearch.setOnFocusChangeListener(new View.OnFocusChangeListener() {
            @Override
            public void onFocusChange(View view, boolean b) {
                if (b && txtSearch.getText().toString().length() > 0)
                    btnClear.setVisibility(View.VISIBLE);
                else
                    btnClear.setVisibility(View.INVISIBLE);
            }
        });

        txtSearch.addTextChangedListener(new TextWatcher() {
            @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(charSequence.length() != 0){
                    btnClear.setVisibility(View.VISIBLE);
                }else{
                    btnClear.setVisibility(View.INVISIBLE);
                }


            }

            @Override
            public void afterTextChanged(Editable editable) {

            }
        });

        list.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
                Intent intent = new Intent(MainActivity.this, SlovoActivity.class);
                CharSequence strCharSequence = ((TextView)view.findViewById(R.id.txtSlovo)).getText();
                String str = strCharSequence.toString().toLowerCase().trim();
                String selectedItem = spinner.getSelectedItem().toString();
                if (selectedItem.equals("С русского на английский")) {
                    intent.putExtra("slovo", str);
                    intent.putExtra("type", "RU");
                    startActivity(intent);
                } else if (selectedItem.equals("С английского на русский")) {
                    intent.putExtra("slovo", str);
                    intent.putExtra("type", "EN");
                    startActivity(intent);
                }
            }
        });

        spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> adapterView, View view, int i, long l) {
                txtSearch.setText("");
                String str = adapterView.getItemAtPosition(i).toString();
                if (str.equals("С русского на английский")) {
                    getSupportLoaderManager().initLoader(0, null, MainActivity.this);
                } else if (str.equals("С английского на русский")) {

                }
            }

            @Override
            public void onNothingSelected(AdapterView<?> adapterView) {

            }
        });
    }

    protected void onDestroy() {
        super.onDestroy();
        // закрываем подключение при выходе
        db.close();
    }

    @Override
    public Loader onCreateLoader(int id, Bundle args) {
        return new MyCursorLoader(this, db);
    }

    @Override
    public void onLoadFinished(Loader<Cursor> loader, Cursor data) {
        cursorAdapter.swapCursor(data);
    }

    @Override
    public void onLoaderReset(Loader<Cursor> loader) {

    }

    static class MyCursorLoader extends CursorLoader {
        DBHeler db;
        public MyCursorLoader(Context context, DBHeler db) {
            super(context);
            this.db = db;
        }

        @Override
        public Cursor loadInBackground() {
            Cursor cursor = db.getRuWords();
            return cursor;
        }

    }
}

我需要当从微调器中选择值“从俄语到英语”时，来自 db.getRuWords() 光标的数据显示在列表视图中，如果选择值“从英语到俄语”，则数据来自显示 db.getEnWords() 光标。代码应该是什么样子，我什么都不懂？

确实如此。但它不起作用

public class MainActivity extends AppCompatActivity implements LoaderManager.LoaderCallbacks<Cursor> {

    private AutoCompleteTextView txtSearch;
    private Spinner spinner;
    private ListView list;
    private ImageButton btnClear;

    private final int RULOADER = 1;
    private final int ENLOADER = 1;

    DBHeler db;

    private MyCursorAdapter cursorAdapter;

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

        db = new DBHeler(this);

        try {
            db.createDataBase();
            db.openDataBase();
        } catch (IOException ex) {
            ex.printStackTrace();
        }

        spinner = (Spinner) findViewById(R.id.spinner);
        // Настраиваем адаптер
        ArrayAdapter<?> adapter =
                ArrayAdapter.createFromResource(this, R.array.types, android.R.layout.simple_spinner_item);
        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        // Вызываем адаптер
        spinner.setAdapter(adapter);

        txtSearch = (AutoCompleteTextView) findViewById(R.id.txtSearch);
        list = (ListView) findViewById(R.id.list);
        btnClear = (ImageButton) findViewById(R.id.btnClear);

        /*Выводим в список все слова, при запуске программы*/
        String selectedItem = spinner.getSelectedItem().toString();
        if (selectedItem.equals("С русского на английский")) {
            cursorAdapter = new MyCursorAdapter(this, R.layout.item, null, 0);
            list.setAdapter(cursorAdapter);
        } else if (selectedItem.equals("С английского на русский")) {
            cursorAdapter = new MyCursorAdapter(this, R.layout.item, null, 0);
            list.setAdapter(cursorAdapter);
        }
    }

    @Override
    protected void onResume() {
        super.onResume();

        txtSearch.setOnFocusChangeListener(new View.OnFocusChangeListener() {
            @Override
            public void onFocusChange(View view, boolean b) {
                if (b && txtSearch.getText().toString().length() > 0)
                    btnClear.setVisibility(View.VISIBLE);
                else
                    btnClear.setVisibility(View.INVISIBLE);
            }
        });

        txtSearch.addTextChangedListener(new TextWatcher() {
            @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(charSequence.length() != 0){
                    btnClear.setVisibility(View.VISIBLE);
                }else{
                    btnClear.setVisibility(View.INVISIBLE);
                }


            }

            @Override
            public void afterTextChanged(Editable editable) {

            }
        });

        list.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
                Intent intent = new Intent(MainActivity.this, SlovoActivity.class);
                CharSequence strCharSequence = ((TextView)view.findViewById(R.id.txtSlovo)).getText();
                String str = strCharSequence.toString().toLowerCase().trim();
                String selectedItem = spinner.getSelectedItem().toString();
                if (selectedItem.equals("С русского на английский")) {
                    intent.putExtra("slovo", str);
                    intent.putExtra("type", "RU");
                    startActivity(intent);
                } else if (selectedItem.equals("С английского на русский")) {
                    intent.putExtra("slovo", str);
                    intent.putExtra("type", "EN");
                    startActivity(intent);
                }
            }
        });

        spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> adapterView, View view, int i, long l) {
                txtSearch.setText("");
                String str = adapterView.getItemAtPosition(i).toString();
                if (str.equals("С русского на английский")) {
                    getSupportLoaderManager().initLoader(RULOADER, null, MainActivity.this);
                    list.setAdapter(cursorAdapter);
                } else if (str.equals("С английского на русский")) {
                    getSupportLoaderManager().initLoader(ENLOADER, null, MainActivity.this);
                    list.setAdapter(cursorAdapter);
                }
            }

            @Override
            public void onNothingSelected(AdapterView<?> adapterView) {

            }
        });
    }

    protected void onDestroy() {
        super.onDestroy();
        // закрываем подключение при выходе
        db.close();
    }

    @Override
    public Loader onCreateLoader(int id, Bundle args) {
        if (id == RULOADER) {
            return new RuWords(MainActivity.this, db);
        } else {
            return new EnWords(MainActivity.this, db);
        }
    }

    @Override
    public void onLoadFinished(Loader<Cursor> loader, Cursor data) {
        //cursorAdapter.swapCursor(data);
        if(loader instanceof RuWords) {
            cursorAdapter.swapCursor(data);
        } else {
            cursorAdapter.swapCursor(data);
        }
    }

    @Override
    public void onLoaderReset(Loader<Cursor> loader) {

    }

    static class RuWords extends CursorLoader {
        DBHeler db;
        public RuWords(Context context, DBHeler db) {
            super(context);
            this.db = db;
        }

        @Override
        public Cursor loadInBackground() {
            Cursor cursor = db.getRuWords();
            return cursor;
        }
    }

    static class EnWords extends CursorLoader {
        DBHeler db;
        public EnWords(Context context, DBHeler db) {
            super(context);
            this.db = db;
        }

        @Override
        public Cursor loadInBackground() {
            Cursor cursor = db.getEnWords();
            return cursor;
        }
    }
}

怎么了？

1 个回答

Voted

pavlofff · Answer 1 · 2020-01-08T11:47:53Z

大约这样的代码，只剩下对示例重要的活动部分（不幸的是，我没有什么可以测试的，因此可能存在小缺陷）。方法和参数中的 ID 指示当前使用的加载器。

public class MainActivity extends AppCompatActivity implements LoaderManager.LoaderCallbacks<Cursor> {

    private Spinner spinner;
    private ListView list;
    static final  int LOADER_RUS = 0;
    static final int LOADER_ENG = 1;

    DBHeler db;

    private MyCursorAdapter cursorAdapter;

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

        db = new DBHeler(this);

        spinner = (Spinner) findViewById(R.id.spinner);
        list = (ListView) findViewById(R.id.list);

        from = new String[] {Contract.Entry.COLUMN_SLOVO, Contract.Entry.COLUMN_SLOVO, Contract.Entry.COLUMN_IZBRANNOE};
        to = new int[] {R.id.txtBukva, R.id.txtSlovo, R.id.btnIzbrannoe};
        cursorAdapter = new MyCursorAdapter(this, R.layout.item, null, from, to, 0);
        list.setAdapter(cursorAdapter);

        // инициализируем оба загрузчика   
        getSupportLoaderManager().initLoader(LOADER_RUS, null, this);
        getSupportLoaderManager().initLoader(LOADER_ENG, null, this);

        spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> adapterView, View view, int loadID, long l) {

                // обновляем данные в курсоре
                getSupportLoaderManager().getLoader(loadID).forceLoad();
            }
            @Override
            public void onNothingSelected(AdapterView<?> adapterView) {
            }
        });


    }

    protected void onDestroy() {
        super.onDestroy();
        db.close();
    }

    @Override
    public Loader onCreateLoader(int id, Bundle args) {

        return new MyCursorLoader(this, db, id);
    }

    @Override
    public void onLoadFinished(Loader<Cursor> loader, Cursor data) {
        cursorAdapter.swapCursor(data);
    }

    @Override
    public void onLoaderReset(Loader<Cursor> loader) {
        cursorAdapter.swapCursor(null);
    }

    static class MyCursorLoader extends CursorLoader {
        Cursor cursor;
        DBHeler db;
        final int LoaderID;
        public MyCursorLoader(Context context, DBHeler db, int id) {
            super(context);
            this.db = db;
            LoaderID = id;
        }

        @Override
        public Cursor loadInBackground() {
          switch (LoaderID) {
                case LOADER_RUS: cursor = db.getRuWords();
                       break;
                case LOADER_ENG: cursor = db.getEnWords();
                       break;
          }
        return cursor;
        }

    }
}

MyCursorLoader将要连接的游标作为第三个参数 ID。

При выборе пункта в спинере обновление загрузчика происходит по нажатой позиции (а не по содержимому пункта списка) - третий аргумент колбэка с именем loadID в данном коде передает позицию выбранного пункта. Позиция может быть 0 или 1, ID наших загрузчиков так же 0 или 1 для русского и английского набора соответственно.

通过 CursorLoader 的两个游标

Python 3.6 - 安装 MySQL (Windows)

C++ 编写程序“计算单个岛屿”。填充一个二维数组 12x12 0 和 1

返回指针的函数

我使用 django 管理面板添加图像，但它没有显示

这些条目是什么意思，它们的完整等效项是什么样的

浏览器仍然缓存文件数据

在 Excel VBA 中激活工作表的问题

为什么内置类型中包含复数而小数不包含？

获得唯一途径

告诉我一个像幻灯片一样创建滚动的库

通过 CursorLoader 的两个游标

1 个回答

相关问题