Question

我用复选框制作了列表视图。我已经阅读了很多人建议在drawlistRow中进行更改的类似文章，但它没有发生。你可以建议我在哪里更改，使其成为一个多行列表。代码片段是：更新：我更新了我的代码但它仍然无法正常工作

 public class CheckboxListField extends MainScreen implements ListFieldCallback, FieldChangeListener {
    int mCheckBoxesCount = 5;
    private Vector _listData = new Vector();
    private ListField listField;
    private ContactList blackBerryContactList;
    private BlackBerryContact blackBerryContact;
    private Vector blackBerryContacts;
    private MenuItem _toggleItem;
    ButtonField button;
    BasicEditField mEdit;
    CheckboxField cb;
    CheckboxField[] chk_service;
    HorizontalFieldManager hm4;
    CheckboxField[] m_arrFields;
     boolean mProgrammatic = false;
     public static StringBuffer sbi = new StringBuffer();
     VerticalFieldManager checkBoxGroup = new VerticalFieldManager();
     LabelField task;

    //A class to hold the Strings in the CheckBox and it's checkbox state (checked or unchecked).
    private class ChecklistData
    {
        private String _stringVal;
        private boolean _checked;

       ChecklistData()
        {
            _stringVal = "";
            _checked = false;
        }

        ChecklistData(String stringVal, boolean checked)
        {
            _stringVal = stringVal;
            _checked = checked;
        }

        //Get/set methods.
        private String getStringVal()
        {
            return _stringVal;
        }

        private boolean isChecked()
        {
            return _checked;
        }

        private void setStringVal(String stringVal)
        {
            _stringVal = stringVal;
        }

        private void setChecked(boolean checked)
        {
            _checked = checked;
        }

        //Toggle the checked status.
        private void toggleChecked()
        {
            _checked = !_checked;
        }
    }

    CheckboxListField()
    {   
        _toggleItem = new MenuItem("Change Option", 200, 10) 
        {
            public void run()
            {
                //Get the index of the selected row.
                int index = listField.getSelectedIndex();

                //Get the ChecklistData for this row.
                ChecklistData data = (ChecklistData)_listData.elementAt(index);

                //Toggle its status.
                data.toggleChecked();

                //Update the Vector with the new ChecklistData.
                _listData.setElementAt(data, index);

                //Invalidate the modified row of the ListField.
                listField.invalidate(index);

               if (index != -1 && !blackBerryContacts.isEmpty())
               {
                   blackBerryContact =
                       (BlackBerryContact)blackBerryContacts.
                       elementAt(listField.getSelectedIndex());
                   ContactDetailsScreen contactDetailsScreen =
                       new ContactDetailsScreen(blackBerryContact);
                   UiApplication.getUiApplication().pushScreen(contactDetailsScreen);
               }
            }
        };   
        listField = new ListField();
        listField.setRowHeight(getFont().getHeight() * 2);
        listField.setCallback(this);
        reloadContactList();

        //CheckboxField[] cb = new CheckboxField[blackBerryContacts.size()];
        for(int count = 0; count < blackBerryContacts.size(); ++count)
        {
            BlackBerryContact item =
                (BlackBerryContact)blackBerryContacts.elementAt(count);
            String displayName = getDisplayName(item);
            CheckboxField cb = new CheckboxField(displayName, false);
            cb.setChangeListener(this);
            add(cb);
            listField.insert(count);
        }
        blackBerryContacts.addElement(cb);
        add(checkBoxGroup);
    }

    protected void makeMenu(Menu menu, int instance)
    {
        menu.add(new MenuItem("Get", 2, 2) {
            public void run() {
                for (int i = 0; i < checkBoxGroup.getFieldCount(); i++) {
                //for(int i=0; i<blackBerryContacts.size(); i++) {
                    CheckboxField checkboxField = (CheckboxField)checkBoxGroup
                        .getField(i);           
                    if (checkboxField.getChecked()) {
                        sbi.append(checkboxField.getLabel()).append("\n");
                    }
                }
                Dialog.inform("Selected checkbox text::" + sbi);
            }
        });
        super.makeMenu(menu, instance);
    }      

    private boolean reloadContactList()
    {
        try {
            blackBerryContactList =
                (ContactList)PIM.getInstance().openPIMList
                (PIM.CONTACT_LIST, PIM.READ_ONLY);

            Enumeration allContacts = blackBerryContactList.items();
            blackBerryContacts = enumToVector(allContacts);
            listField.setSize(blackBerryContacts.size());
            return true;
        }   catch (PIMException e)
        {
          return false;
        }
    } 

    //Convert the list of contacts from an Enumeration to a Vector
    private Vector enumToVector(Enumeration contactEnum) {
        Vector v = new Vector();

        if (contactEnum == null)
          return v;

        while (contactEnum.hasMoreElements()) {
          v.addElement(contactEnum.nextElement());
        }

        return v;
      }

    public void drawListRow(ListField list, Graphics graphics, int index, int y, int w) 
    {
        ChecklistData currentRow = (ChecklistData)this.get(list, index); 
        StringBuffer rowString = new StringBuffer();

        if (currentRow.isChecked())
        {
            rowString.append(Characters.BALLOT_BOX_WITH_CHECK);
        }
        else
        {
            rowString.append(Characters.BALLOT_BOX);
        }

        //Append a couple spaces and the row's text.
        rowString.append(Characters.SPACE);
        rowString.append(Characters.SPACE);
        rowString.append(currentRow.getStringVal());

        //graphics.drawText("ROW", 0, y, 0, w);
        //String rowNumber = "one";
        //Draw the text.
        graphics.drawText(rowString.toString(), 0, y, 0, w);
        /*graphics.drawText("ROW " + rowNumber, y, 0, w);
        graphics.drawText("ROW NAME", y, 20, w);
        graphics.drawText("row details", y + getFont().getHeight(), 20, w); */
    }

    public void drawRow(Graphics g, int x, int y, int width, int height) {
        // Arrange the cell fields within this row manager.
        layout(width, height);

        // Place this row manager within its enclosing list.
        setPosition(x, y);

        // Apply a translating/clipping transformation to the graphics
        // context so that this row paints in the right area.
        g.pushRegion(getExtent());

        // Paint this manager's controlled fields.
        subpaint(g);

        g.setColor(0x00CACACA);
        g.drawLine(0, 0, getPreferredWidth(), 0);

        // Restore the graphics context.
        g.popContext();
    }
    public static String getDisplayName(Contact contact) 
      {
          if (contact == null)
          {
              return null;    
          }

          String displayName = null;

          // First, see if there is a meaningful name set for the contact.
          if (contact.countValues(Contact.NAME) > 0) {
              final String[] name = contact.getStringArray(Contact.NAME, 0);
              final String firstName = name[Contact.NAME_GIVEN];
              final String lastName = name[Contact.NAME_FAMILY];
              if (firstName != null && lastName != null) {
                  displayName = firstName + " " + lastName;
              } else if (firstName != null) {
                  displayName = firstName;
              } else if (lastName != null) {
                  displayName = lastName;
              }

              if (displayName != null) {
                  final String namePrefix = name[Contact.NAME_PREFIX];
                  if (namePrefix != null) {
                      displayName = namePrefix + " " + displayName;
                  }
                  return displayName;
              }
          }
          return displayName;
      }

    //Returns the object at the specified index.
    public Object get(ListField list, int index) 
    { 
        return _listData.elementAt(index);
        /*if (listField == list)
        {
            //If index is out of bounds an exception will be thrown,
            //but that's the behaviour we want in that case.
            //return blackBerryContacts.elementAt(index);
            _listData = (Vector) blackBerryContacts.elementAt(index);
            return _listData.elementAt(index);
        }
        return null;*/
    }

    //Returns the first occurence of the given String, bbeginning the search at index, 
    //and testing for equality using the equals method.
    public int indexOfList(ListField list, String p, int s) 
    {
        //return listElements.getSelectedIndex();
        //return _listData.indexOf(p, s);
        return -1;
    }

    //Returns the screen width so the list uses the entire screen width.
    public int getPreferredWidth(ListField list) 
    {
        return Graphics.getScreenWidth();
        //return Display.getWidth();
    }

    public void fieldChanged(Field field, int context) {
      boolean mProgrammatic = false;

        if (!mProgrammatic) {
        mProgrammatic = true;
        CheckboxField cbField = (CheckboxField) field;
        int index = blackBerryContacts.indexOf(cbField);

        if (cbField.getChecked())
        {
           for(int i=0;i<blackBerryContacts.size();i++)
           {
           Dialog.inform("Selected::" + cbField.getLabel());
           sbi=new StringBuffer();
           sbi.append(cbField.getLabel());

           }                 
        }

        mProgrammatic = false;
    }

    }

Answer 1

此代码可能会改进：

使用ListField而不是VerticalFieldManager + CheckboxField数组（ListField更快，100多个控件可能会降低UI的速度）
在列表数据中使用简单数组而不是向量（它更快）
从UI线程移动联系人加载（我们应该知道阻止UI线程与IO，网络或使用联系人列表等繁重程序）

实际上使用带有两行行的ListField有一个问题：我们必须为ListField中的所有行设置相同的高度。因此，无论我们是否使用第二行，每行总有两行。但它确实比UI性能问题更好。

参见代码：

public class CheckboxListField extends MainScreen implements
        ListFieldCallback {
    private ChecklistData[] mListData = new ChecklistData[] {};
    private ListField mListField;
    private Vector mContacts;
    private MenuItem mMenuItemToggle = new MenuItem(
            "Change Option", 0, 0) {
        public void run() {
            toggleItem();
        };
    };

    private MenuItem mMenuItemGet = new MenuItem("Get", 0,
            0) {
        public void run() {
            StringBuffer sbi = new StringBuffer();
            for (int i = 0; i < mListData.length; i++) {
                ChecklistData checkboxField = mListData[i];
                if (checkboxField.isChecked()) {
                    sbi.append(checkboxField.getStringVal())
                            .append("\n");
                }
            }
            Dialog.inform("Selected checkbox text::\n"
                    + sbi);
        }
    };

    // A class to hold the Strings in the CheckBox and it's checkbox state
    // (checked or unchecked).
    private class ChecklistData {
        private String _stringVal;
        private boolean _checked;

        ChecklistData(String stringVal, boolean checked) {
            _stringVal = stringVal;
            _checked = checked;
        }

        // Get/set methods.
        private String getStringVal() {
            return _stringVal;
        }

        private boolean isChecked() {
            return _checked;
        }

        // Toggle the checked status.
        private void toggleChecked() {
            _checked = !_checked;
        }
    }

    CheckboxListField() {
        // toggle list field item on navigation click
        mListField = new ListField() {
            protected boolean navigationClick(int status,
                    int time) {
                toggleItem();
                return true;
            };
        };
        // set two line row height
        mListField.setRowHeight(getFont().getHeight() * 2);
        mListField.setCallback(this);
        add(mListField);

        // load contacts in separate thread
        loadContacts.run();
    }

    protected Runnable loadContacts = new Runnable() {
        public void run() {
            reloadContactList();
            // fill list field control in UI event thread
            UiApplication.getUiApplication().invokeLater(
                    fillList);
        }
    };

    protected Runnable fillList = new Runnable() {
        public void run() {
            int size = mContacts.size();
            mListData = new ChecklistData[size];
            for (int i = 0; i < mContacts.size(); i++) {
                BlackBerryContact item = (BlackBerryContact) mContacts
                        .elementAt(i);
                String displayName = getDisplayName(item);
                mListData[i] = new ChecklistData(
                        displayName, false);
            }
            mListField.setSize(size);
        }
    };

    protected void toggleItem() {
        // Get the index of the selected row.
        int index = mListField.getSelectedIndex();
        if (index != -1) {
            // Get the ChecklistData for this row.
            ChecklistData data = mListData[index];

            // Toggle its status.
            data.toggleChecked();

            // Invalidate the modified row of the ListField.
            mListField.invalidate(index);

            BlackBerryContact contact = (BlackBerryContact) mContacts
                    .elementAt(mListField
                            .getSelectedIndex());

            // process selected contact here

        }
    }

    protected void makeMenu(Menu menu, int instance) {
        menu.add(mMenuItemToggle);
        menu.add(mMenuItemGet);
        super.makeMenu(menu, instance);
    }

    private boolean reloadContactList() {
        try {
            ContactList contactList = (ContactList) PIM
                    .getInstance()
                    .openPIMList(PIM.CONTACT_LIST,
                            PIM.READ_ONLY);

            Enumeration allContacts = contactList.items();
            mContacts = enumToVector(allContacts);
            mListField.setSize(mContacts.size());
            return true;
        } catch (PIMException e) {
            return false;
        }
    }

    // Convert the list of contacts from an Enumeration to a Vector
    private Vector enumToVector(Enumeration contactEnum) {
        Vector v = new Vector();

        if (contactEnum == null)
            return v;

        while (contactEnum.hasMoreElements()) {
            v.addElement(contactEnum.nextElement());
        }

        return v;
    }

    public void drawListRow(ListField list,
            Graphics graphics, int index, int y, int w) {
        Object obj = this.get(list, index);
        if (obj != null) {
            ChecklistData currentRow = (ChecklistData) obj;
            StringBuffer rowString = new StringBuffer();

            if (currentRow.isChecked()) {
                rowString
                        .append(Characters.BALLOT_BOX_WITH_CHECK);
            } else {
                rowString.append(Characters.BALLOT_BOX);
            }
            // Append a couple spaces and the row's text.
            rowString.append(Characters.SPACE);
            rowString.append(Characters.SPACE);
            rowString.append(currentRow.getStringVal());
            // Draw the text.
            graphics.drawText(rowString.toString(), 0, y,
                    0, w);
            String secondLine = "Lorem ipsum dolor sit amet, "
                    + "consectetur adipiscing elit.";
            graphics.drawText(secondLine, 0, y
                    + getFont().getHeight(),
                    DrawStyle.ELLIPSIS, w);
        } else {
            graphics.drawText("No rows available.", 0, y,
                    0, w);
        }
    }

    public static String getDisplayName(Contact contact) {
        if (contact == null) {
            return null;
        }
        String displayName = null;
        // First, see if there is a meaningful name set for the contact.
        if (contact.countValues(Contact.NAME) > 0) {
            final String[] name = contact.getStringArray(
                    Contact.NAME, 0);
            final String firstName = name[Contact.NAME_GIVEN];
            final String lastName = name[Contact.NAME_FAMILY];
            if (firstName != null && lastName != null) {
                displayName = firstName + " " + lastName;
            } else if (firstName != null) {
                displayName = firstName;
            } else if (lastName != null) {
                displayName = lastName;
            }
            if (displayName != null) {
                final String namePrefix = name[Contact.NAME_PREFIX];
                if (namePrefix != null) {
                    displayName = namePrefix + " "
                            + displayName;
                }
                return displayName;
            }
        }
        return displayName;
    }

    // Returns the object at the specified index.
    public Object get(ListField list, int index) {
        Object result = null;
        if (mListData.length > index) {
            result = mListData[index];
        }
        return result;
    }

    // Returns the first occurrence of the given String,
    // beginning the search at index, and testing for
    // equality using the equals method.
    public int indexOfList(ListField list, String p, int s) {
        return -1;
    }

    // Returns the screen width so the list uses the entire screen width.
    public int getPreferredWidth(ListField list) {
        return Graphics.getScreenWidth();
        // return Display.getWidth();
    }
}

blackberry chackbox two lines per row list field

有一个很好的编码！

黑莓：多行ListView

1 个答案: