setValueAt(Object aValue，int row，int col) [英] setValueAt(Object aValue, int row, int col)

问题描述

我正在尝试更改defaultTableModel中Object [] []数据中的值，但在if (data[i][j] == userFolderName)处出现了nullpointerexception我试图将变量更改为"Kathy"，以防万一它没有读取userName正确，但仍会引发异常.你能看一下我的代码，看看我出了什么问题吗?

I am trying to change a value in the Object[][] data in a defaultTableModel but I am getting a nullpointerexception at if (data[i][j] == userFolderName)I have tried changing the variable to "Kathy" just in case it wasn't reading the userName correctly but it still throws the exception. Can you please have a look at my code and see where I'm going wrong?

public class Statistics extends JPanel {
    public Object[][] data;
    public DefaultTableModel model;

public Statistics() {
    super(new GridLayout(1,0));
    String[] columnNames = {"Name", "Games Played", "Games Won"};
    Object[][] data = {
            {"Kathy", new Integer(5), new Integer(2)},
            {"Steve", new Integer(2), new Integer(0)},
    };
    model = new DefaultTableModel(data, columnNames);
    JTable table = new JTable(model);
    table.setFillsViewportHeight(true);
    table.setVisible(true);
    table.setEnabled(false);

    JScrollPane scrollPane = new JScrollPane(table);
    add(scrollPane);
}

public void addRow(Object[] objects) {
    model.addRow(objects);

}

public void updateGamesPlayed(String userFolderName, int gamesPlayed) {
    int rowCount = model.getRowCount();
    int columnCount = model.getColumnCount();
    for (int i = 0; i < rowCount; i++){
        for(int j = 0; j < columnCount; j++){
            if (data[i][j] == userFolderName){
                model.setValueAt(gamesPlayed, i, j+1);
            }
        }
    }

}


}

推荐答案

您有两个不同的data对象-构造函数中的一个全局对象和一个局部对象.如果在构造函数中将Object[][] data = {...};更改为data = new Object[][]{...};，则它应该可以工作，因为您只设置本地值，而不是全局值.

You have two different data objects - a global one and a local one in your constructor. If you change Object[][] data = {...}; to data = new Object[][]{...}; in your constructor it should work as you're only setting the local one, not the global value.

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