1

我有 3 节课

从数据库获取数据的冷杉

普通作品第二名

其他用于展示表。

public class TableContent {

private final Vector<String> headers;
private final Vector<Vector<String>> content;

public TableContent(final Vector<String> headers, final Vector<Vector<String>> content) {
    this.headers = headers;
    this.content = content;
}

public Vector<String> headers() {
    return headers;
}

public Vector<Vector<String>> content() {
    return content;
}
}

和：

public class TableData {

public TableContent getData() {
    Vector<String> headers = new Vector<String>();
    Vector<Vector<String>> content = new Vector<Vector<String>>();

    try {
        Connection conn = DriverManager.getConnection("");
        Statement statement = conn.createStatement();
        ResultSet rs = statement.executeQuery("Select * from table");

        headers = buildHeaders(rs);
        content = buildContent(rs);

    } catch (SQLException e) {
        e.printStackTrace();
    }

    return new TableContent(headers, content);
}

private Vector<String> buildHeaders(final ResultSet rs) throws SQLException {
    Vector<String> headers = new Vector<String>();

    int col = rs.getMetaData().getColumnCount();
    for (int i = 1; i <= col; i++) {
        headers.add(rs.getMetaData().getColumnName(i));
    }
    return headers;
}

private Vector<Vector<String>> buildContent(final ResultSet rs) throws SQLException {
    Vector<Vector<String>> content = new Vector<Vector<String>>();

    while (rs.next()) {
        int col = rs.getMetaData().getColumnCount();
        Vector<String> newRow = new Vector<String>(col);

        for (int i = 1; i <= col; i++) {
            newRow.add(rs.getString(i));
        }
        content.add(newRow);
    }
    return content;
}
}

和：

public class TableGUI extends JFrame {

JTable table;
TableContent data = new TableData().getData();

public TableGUI() {
    table = new JTable(new DefaultTableModel(data.headers(), data.content()));

    add(new JScrollPane(table), BorderLayout.CENTER);

    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setSize(700, 550);
    setLocation(300, 80);
    setVisible(true);
}

public static void main(String[] args) {
    new TableGUI();
}
}

输出：

Exception in thread "main" java.lang.ClassCastException: java.lang.String cannot be cast to java.util.Vector
at javax.swing.table.DefaultTableModel.justifyRows(DefaultTableModel.java:268)
at javax.swing.table.DefaultTableModel.setDataVector(DefaultTableModel.java:224)
at javax.swing.table.DefaultTableModel.<init>(DefaultTableModel.java:159)
at TableGUI.<init>(TableGUI.java:11)
at TableGUI.main(TableGUI.java:22)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:601)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:120)

我的错误在哪里？

4

2 回答 2

2

我认为您将错误的参数传递给构造函数。根据构造函数文档，您必须将内容作为第一个参数，将标头数据作为第二个参数。

因此，您应该尝试翻转DefaultTableModel代码中的参数：

table = new JTable(new DefaultTableModel(data.content(), data.headers()));
于 2013-09-02T20:27:55.580 回答
2

我强烈怀疑问题在于您以错误的顺序传递参数。的第一个参数DefaultTableModel(Vector, Vector)是数据。这是第二个参数，它是列名。所以试试这个：

table = new JTable(new DefaultTableModel(data.content(), data.headers()));
于 2013-09-02T20:26:15.847 回答