java - 使用自定义 TableCellRenderer 的 Swing JTable

Question

在我的java应用程序中，我想设置颜色以及选择它时的行为。为此，我编写了 TableCellRenderer 的自定义实现，它可以按我想要的方式工作。但有件事我还是很困惑......

这是TableCellRenderer的实现:

public class AccountMovementTableCellRenderer extends JLabel implements TableCellRenderer{
    @Override
    public Component getTableCellRendererComponent(JTable table, Object value, boolean  isSelected, boolean hasFocus, int row, int column){     
        //My implementation here...
        return this;
    }
}

这里是JTable的创建:

AccountMovementTableCellRenderer accountMovementCellRenderer = new AccountMovementTableCellRenderer();
entryTable = new JTable(entryModel){
    private static final long serialVersionUID = 1L;

    @Override
    public TableCellRenderer getCellRenderer(int row, int column){
        return accountMovementCellRenderer;
    }
};

我只创建了一个 CellRenderer 实例，但我原本期望每个单元格有一个 CellRenderer，但我很惊讶它竟然以这种方式工作...每个单元格的内容和颜色都不同，但它始终使用相同的 CellRenderer 实例，那么这怎么行呢？

Answer 1

TableCellRenderer.prepareRenderer 返回的组件被重用来渲染 JTable 的内容 - 在您的情况下，您的渲染器扩展了 JLabel (您可以只扩展 DefaultTableCellRenderer) - 此 JLabel 用于绘制 JTable 的内容。 prepareRenderer 方法用于在渲染之前为每个单元格自定义 JLabel。引用Oracle's tutorial on the JTables

You might expect each cell in a table to be a component. However, for performance reasons, Swing tables are implemented differently.

Instead, a single cell renderer is generally used to draw all of the cells that contain the same type of data. You can think of the renderer as a configurable ink stamp that the table uses to stamp appropriately formatted data onto each cell. When the user starts to edit a cell's data, a cell editor takes over the cell, controlling the cell's editing behavior.