Java，将单元格内容更改为同一行中另一个单元格的函数 [英] Java, change a cell content as a function of another cell in the same row
问题描述
我的问题需要一些帮助。我有一张桌子，例如双列和字符串列。如果双列中的值为negativ，则字符串应为negativ。另一方面，如果值为positiv，则字符串应为positiv。
问题是现在如果我在jTable中编辑double值，字符串也应该更新。
I need some help for my problem. I have a table with e.g. a double column and a string column. If the value in the double column is negativ, the string should be "negativ". And the other way if the value is positiv, the string should be "positiv". The problem is now if I edit the double value in the jTable, the string should also be updated.
更新我的问题，实际代码看起来像这样：
但它不起作用，因为在编辑第一列值后，第二列中的字符串不会更新。它仅在我第一次启动程序时有效。
Update to my question, the actual code look like this: But it doesn't work, because the string in the second column wont be updated after I edit the first column value. It only works when I start the program the first time.
import java.util.Vector;
import javax.swing.*;
import javax.swing.event.TableModelEvent;
import javax.swing.event.TableModelListener;
import javax.swing.table.*;
public class ExampleRemoveAddRows extends JFrame {
private Object[] columnNames = {"Double", "positiv / negativ"};
private Object[][] data = {
{new Double(10.0), "positiv"},
{new Double(-10.0), "negativ"},
{new Double(20.0), "positiv"},
{new Double(-30.0), "negativ"}
};
private JTable table;
private DefaultTableModel model;
public ExampleRemoveAddRows() {
model = new DefaultTableModel(data, columnNames) {
@Override
public Class getColumnClass(int column) {
return getValueAt(0, column).getClass();
}
@Override
public Object getValueAt(int row, int column) {
if (column == 1) {
double number = Double.parseDouble(this.getValueAt(row, 0).toString());
System.out.println(number);
System.out.println("good");
System.out.println((number < 0) ? "negativ" : "positiv");
return "C: "+ this.getValueAt(row, 0);//((number < 0) ? "negativ" : "positiv");
} else {
return super.getValueAt(row, column);
}
}
};
table = new JTable(model);
table.setPreferredScrollableViewportSize(table.getPreferredSize());
JScrollPane scrollPane = new JScrollPane(table);
add(scrollPane);
}
public static void main(String[] args) {
javax.swing.SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
ExampleRemoveAddRows frame = new ExampleRemoveAddRows();
frame.setDefaultCloseOperation(EXIT_ON_CLOSE);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
}
感谢您的帮助。
Sam
推荐答案
我修改了你的sscce以显示建议的替代方法此处。注意获得 Double 常量的替代方法。我还重新考虑了 String 约束。
I've revised your sscce to show the alternate approach suggested here. Note the alternate ways to get a Double constant. I've also re-factored the String constrants.
补遗：@kleopatra在有用的评论中观察到查询模型直接产生正确的结果，但 TableModelListener 只能看到第0列的更改，而不是第1列。简单的权宜之计是使第1列非 -editable，因为它的值完全取决于第0列。
Addendum: In helpful comments, @kleopatra observes that querying the model directly will always produce the correct result, but a TableModelListener will only see changes to column 0, not column 1. The simple expedient is to make column 1 non-editable, as its value depends completely on column 0.
@Override
public boolean isCellEditable(int row, int col) {
return col == 0;
}
下面的第一个示例使用 DefaultTableModel ：
The first example below uses DefaultTableModel:
import javax.swing.*;
import javax.swing.table.*;
/** @see https://stackoverflow.com/a/13628183/230513 */
public class ExampleRemoveAddRows extends JFrame {
public static final String NEGATIVE = "negativ";
public static final String POSITIVE = "positiv";
private Object[] columnNames = {"Double", POSITIVE + " / " + NEGATIVE};
private Object[][] data = {
{10d, null},
{-10.0, null},
{Double.valueOf(30), null},
{Double.valueOf("-30"), null}
};
private JTable table;
private DefaultTableModel model;
public ExampleRemoveAddRows() {
model = new DefaultTableModel(data, columnNames) {
@Override
public Class getColumnClass(int column) {
return getValueAt(0, column).getClass();
}
@Override
public boolean isCellEditable(int row, int col) {
return col == 0;
}
@Override
public Object getValueAt(int row, int col) {
if (col == 1) {
double number = (Double) this.getValueAt(row, 0);
return (number < 0) ? NEGATIVE : POSITIVE;
} else {
return super.getValueAt(row, col);
}
}
@Override
public void setValueAt(Object aValue, int row, int col) {
super.setValueAt(aValue, row, col);
fireTableCellUpdated(row, 1); // may have changed
}
};
table = new JTable(model);
table.setPreferredScrollableViewportSize(table.getPreferredSize());
JScrollPane scrollPane = new JScrollPane(table);
add(scrollPane);
}
public static void main(String[] args) {
javax.swing.SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
ExampleRemoveAddRows frame = new ExampleRemoveAddRows();
frame.setDefaultCloseOperation(EXIT_ON_CLOSE);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
}
此变体扩展AbstractTableModel ：
import java.awt.EventQueue;
import java.util.ArrayList;
import java.util.List;
import javax.swing.*;
import javax.swing.table.*;
/**
* @see https://stackoverflow.com/a/13628183/230513
*/
public class ExampleRemoveAddRows extends JFrame {
public static final String NEGATIVE = "negativ";
public static final String POSITIVE = "positiv";
public ExampleRemoveAddRows() {
DoubleModel model = new DoubleModel();
model.add(10.1);
model.add(-10.2);
model.add(Double.valueOf(30.1));
model.add(Double.valueOf("-30.2"));
JTable table = new JTable(model);
table.setPreferredScrollableViewportSize(table.getPreferredSize());
JScrollPane scrollPane = new JScrollPane(table);
add(scrollPane);
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
ExampleRemoveAddRows frame = new ExampleRemoveAddRows();
frame.setDefaultCloseOperation(EXIT_ON_CLOSE);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
private class DoubleModel extends AbstractTableModel {
List<Double> data = new ArrayList<Double>();
public void add(Double d) {
data.add(d);
}
@Override
public int getRowCount() {
return data.size();
}
@Override
public int getColumnCount() {
return 2;
}
@Override
public String getColumnName(int col) {
if (col == 0) {
return "Double";
} else {
return POSITIVE + " / " + NEGATIVE;
}
}
@Override
public Class<?> getColumnClass(int col) {
if (col == 0) {
return Double.class;
} else {
return String.class;
}
}
@Override
public boolean isCellEditable(int row, int col) {
return col == 0;
}
@Override
public Object getValueAt(int row, int col) {
if (col == 0) {
return data.get(row);
} else {
double number = (Double) this.getValueAt(row, 0);
return (number < 0) ? NEGATIVE : POSITIVE;
}
}
@Override
public void setValueAt(Object aValue, int row, int col) {
if (col == 0) {
data.set(row, (Double) aValue);
fireTableRowsUpdated(row, row);
}
}
}
}
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