java - 表模型问题

Question

我很困惑，我已经重新设计了我的表模型 20 次。我开始认为我的问题可能不在我的表模型或数据源中，而是在我的 MainView 中。我以前从未使用过 tabbedpanes...也许它不喜欢选项卡？最后提到了我的 mainView 代码。

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at javax.swing.JTable.prepareRenderer(Unknown Source)
at javax.swing.plaf.basic.BasicTableUI.paintCell(Unknown Source)
at javax.swing.plaf.basic.BasicTableUI.paintCells(Unknown Source)
at javax.swing.plaf.basic.BasicTableUI.paint(Unknown Source)
at javax.swing.plaf.ComponentUI.update(Unknown Source)
at javax.swing.JComponent.paintComponent(Unknown Source)
at javax.swing.JComponent.paint(Unknown Source)
at javax.swing.JComponent.paintChildren(Unknown Source)
at javax.swing.JComponent.paint(Unknown Source)
at javax.swing.JViewport.paint(Unknown Source)
at javax.swing.JComponent.paintChildren(Unknown Source)
at javax.swing.JComponent.paint(Unknown Source)
at javax.swing.JComponent.paintChildren(Unknown Source)
at javax.swing.JComponent.paint(Unknown Source)
at javax.swing.JComponent.paintChildren(Unknown Source)
at javax.swing.JComponent.paint(Unknown Source)
at javax.swing.JComponent.paintToOffscreen(Unknown Source)
at javax.swing.RepaintManager$PaintManager.paintDoubleBuffered(Unknown Source)
at javax.swing.RepaintManager$PaintManager.paint(Unknown Source)
at javax.swing.RepaintManager.paint(Unknown Source)
at javax.swing.JComponent._paintImmediately(Unknown Source)
at javax.swing.JComponent.paintImmediately(Unknown Source)
at javax.swing.RepaintManager$3.run(Unknown Source)
at javax.swing.RepaintManager$3.run(Unknown Source)

我的表模型

public class MyTable implements TableModel{

ArrayList<Inventory> inventoryList;
MyDataSource source = new MyDataSource();

String[] columnNames = {"ID","Product","Price","Instock","Sold"};

public MyTable(){

    inventoryList = source.getInventory();
}

@Override
public void addTableModelListener(TableModelListener l) {

}

@Override
public Class<?> getColumnClass(int columnIndex) {

    return null;
}

@Override
public int getColumnCount() {
    return 5;
}

@Override
public String getColumnName(int columnIndex) {
    return columnNames[columnIndex];
}

@Override
public int getRowCount() {
    return inventoryList.size();
}

@Override
public Object getValueAt(int row, int col) {

    Inventory inventory = inventoryList.get(row);
    switch(col){
    case 0: return inventory.getID();
    case 1: return inventory.getProductName();
    case 2: return inventory.getPrice();
    case 3: return inventory.getInstock();
    case 4: return inventory.getSold();
    }

    return null;
}

@Override
public boolean isCellEditable(int rowIndex, int columnIndex) {

    return false;
}

@Override
public void removeTableModelListener(TableModelListener l) {

}

@Override
public void setValueAt(Object aValue, int rowIndex, int columnIndex) {

}

}

我的主课

        JScrollPane scrollPane = new JScrollPane();
    tabbedPane.addTab("Database", null, scrollPane, null);

    table = new JTable(tableModel);
    scrollPane.setViewportView(table);      

Answer 1

你的错误在这里

@Override
public Class<?> getColumnClass(int columnIndex) {
    return null;
}

您正在使用表的默认渲染器，因此您必须指定列类。但是你返回 null 而不是它，尝试用 String.class 替换它，它会起作用。