Question

我正在尝试在容器中实现JPanel列表。出于某种原因，我无法将面板对齐到顶部

gbc.anchor = GridBagConstraints.NORTH; gbc.weighty = 1;

gbc.anchor = GridBagConstraints.NORTH; gbc.weighty = 0;

正如您所看到的，对齐顶部仅适用于重量＆gt; 0

以下列方式创建容器：

public ListSection() 
{
    setLayout( new BoxLayout( this, BoxLayout.Y_AXIS ) );
    mainList = new JPanel( new GridBagLayout() );
    mainList.setBorder( BorderFactory.createLineBorder( Color.cyan, 2 ) );

    JScrollPane scrollPane = new JScrollPane( mainList, JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED, JScrollPane.HORIZONTAL_SCROLLBAR_NEVER );
    scrollPane.setBorder( null );
    scrollPane.setVerticalScrollBar( new HScrollBar() );
    add( scrollPane );
}

然后从另一个类调用它：

mainListSection = new ListSection( );
messagesContainer.add( mainListSection );

正在添加JPanels：

public static void addToMainList( List<Message> messages )
{       
    mainListSection.getMainList().removeAll();

    GridBagConstraints gbc = new GridBagConstraints();
    gbc.anchor = GridBagConstraints.NORTH;
    gbc.gridwidth = GridBagConstraints.REMAINDER;
    gbc.weightx = 1;
    gbc.weighty = 0;
    gbc.fill = GridBagConstraints.BOTH;

    for( Message message : messages )
    {   
        if( Toolbar.getFilterParameter().equals( "all" ) )
        {
            JPanel panel = MessageBlock.buildBlock( message );
            mainListSection.getMainList().add( panel, gbc );
        }
        else
        {
            if( Toolbar.getFilterParameter().equals( "catalogue" ) && 
                ( message.type.equals( "users" ) || message.type.equals( "userpersonals" ) ) )
            {
                JPanel panel = MessageBlock.buildBlock( message );
                mainListSection.getMainList().add( panel, gbc );
            }
            else if( Toolbar.getFilterParameter().equals( message.type ) )
            {
                JPanel panel = MessageBlock.buildBlock( message );
                mainListSection.getMainList().add( panel, gbc );
            }
        }
    }
    mainListSection.validate();
    mainListSection.repaint();
}

因此，当我尝试将weighty设置为0时会出现问题。这会将垂直对齐设置为居中。

如果能以某种方式解决这个问题，可以请任何人提出建议吗？

提前致谢

修改

在MadProgrammer的帮助下，我设法解决了这个问题。我所要做的就是将weighty = 1设置为循环中的最后一项。所以更新后的代码如下：

public static void addToMainList( List<Message> messages )
{       
    mainListSection.getMainList().removeAll();

    GridBagConstraints gbc = new GridBagConstraints();
    gbc.anchor = GridBagConstraints.NORTH;
    gbc.gridwidth = GridBagConstraints.REMAINDER;
    gbc.weightx = 1;
    gbc.fill = GridBagConstraints.BOTH;

    int i = 1;
    for( Message message : messages )
    {   
        gbc.weighty = ( i != messages.size() ) ? 0 : 1;

        if( Toolbar.getFilterParameter().equals( "all" ) )
        {
            JPanel panel = MessageBlock.buildBlock( message );
            mainListSection.getMainList().add( panel, gbc );
        }
        else
        {
            if( Toolbar.getFilterParameter().equals( "catalogue" ) && 
                ( message.type.equals( "users" ) || message.type.equals( "userpersonals" ) ) )
            {
                JPanel panel = MessageBlock.buildBlock( message );
                mainListSection.getMainList().add( panel, gbc );
            }
            else if( Toolbar.getFilterParameter().equals( message.type ) )
            {
                JPanel panel = MessageBlock.buildBlock( message );
                mainListSection.getMainList().add( panel, gbc );
            }
        }
        i++;
    }
    mainListSection.validate();
    mainListSection.repaint();
}

当gbc.weighty = 0时，GridBagConstraints.NORTH不会将面板对齐到顶部

0 个答案: