Question

我正在实现一种表格。为此，我使用了AbstractTableModel，但我不知道我的代码在做什么（这就是为什么我得到了一个完成他的工作的片段，但显然我想理解）。你可以看到代码

public class TablePanel extends JPanel
{
    private JTable table;
    public TablePanel()
    {
        setLayout(new BoxLayout(this, BoxLayout.Y_AXIS)); 
        table = new JTable(new MyTableModel());
        table.setFillsViewportHeight(true);     
        table.setPreferredScrollableViewportSize(new Dimension(500, 100));
        JScrollPane jps = new JScrollPane(table);
        add(jps);
        add(new JScrollPane(table));
        table.setCellSelectionEnabled(true);
    }
    private class MyTableModel extends AbstractTableModel {
        private String[] columns = {"","Monday","Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"};
        private String[][] data = {{"8:30 - 9:30","","","","","",""},
            {"9:30 - 10:30","","","","","",""},
            {"10:30 - 11:30","","","","","",""},
            {"11:30 - 12:30","","","","","",""},
            {"12:30 - 13:30","","","","","",""},
            {"13:30 - 14:30","","","","","",""},
            {"14:30 - 15:30","","","","","",""},
            {"15:30 - 16:30","","","","","",""},
            {"16:30 - 17:30","","","","","",""}};

        public int getColumnCount() {
            return columns.length;
        }

        public int getRowCount() {
            return data.length;
        }

        public String getColumnName(int col) {
            return columns[col];
        }

        public Object getValueAt(int row, int col) {
            return data[row][col];
        }
        public Object myMethod (){
            //do something
        }
    }
}

嗯，这是什么意思table = new JTable(new MyTableModel());？我认为table将是MyTableModel实例，但事实并非如此。实际上，如果我将表传递给另一个外部类，则此类将不会看到myMethod正文中定义的方法MyTableModel。

Answer 1

MyTableModel是TableModel，但TableModel 不必然是MyTableModel。

如您所知，您的表格模型是MyTableModel的实例，其中包含所需的myMethod()，您可以使用强制转换：

JTable table = new JTable(new MyTableModel());
MyTableModel model = (MyTableModel) table.getModel();

创建和使用对模型的引用可能更容易：

MyTableModel model = new MyTableModel();
JTable table = new JTable(model);

请勿忽略setValueAt()的实施，here。

Answer 2

JTable构造函数接受实现TableModel接口

的类的任何Object

this将帮助您了解更多信息。

Answer 3

其他类无法看到函数myMethod的预期行为，因为它们“认为”你的MyTableModel只是一个AbstractTableModel（实际上它不是）您放入MyTableModel的代码和其他所有内容都是正确的，但您无法看到函数myMethod 那是因为你使用的是OOP语言

所以没错。您正在创建MyTableModel的实例，因此如果您调用

，将执行您在其中执行的所有操作

你应该在这里阅读，这将解释有关OOP部分的更多信息： http://www.dummies.com/how-to/content/understanding-javas-objectoriented-programming-oop.html

只是快速说出来

如果您需要访问myMethod函数，只需将其转换为： //创建MyTableInstance（这是可能的，因为AbstractTableModel是父项，MyTableModel是子项） AbstractTableModel atmTestVariable = new MyTableModel（）;

 // Now to be able to call this:
 // atmTestVariable.myMethod();
 // we need to do this:

 if(atmTestVariable isntanceof MyTableModel) //make sure that atmTestVariable is REALY a MyTableModel
 {
    MyTableModel mtmTemp = (MyTableModel)atmTestVariable; //cast to MyTableModel
    mtmTemp.myMethod(); //Call the function
    // and now the short variant:
    ((MyTableModel)atmTestVariable).myMethod(); //cast to MyTableModel AND call the function
 }

希望我能够提供帮助

哦，请将MyTabelModel类的定义移动到一个单独的文件中：/

不了解定义的Constructor的Java语法

3 个答案: