I have some data in MySQL which has to be retrieved and showed in JTable. Code I wrote for that is as follows
PreparedStatement ps = con.prepareStatement("select * from " + chosenClass
+ " where subjects=?;");
ps.setString(1, selectedGroup);
rs = ps.executeQuery();
rs.next();
subjects[0] = rs.getString("sub1");
subjects[1] = rs.getString("sub2");
subjects[2] = rs.getString("sub3");
subjects[3] = rs.getString("sub4");
subjects[4] = rs.getString("sub5");
subjects[5] = "H.V";
tableModel.setColumnIdentifiers(new Object[]{"RollNo", "Name", subjects[0], subjects[1],
subjects[2], subjects[3], subjects[4], subjects[5]});
tableModel = (DefaultTableModel) StuMarks_TBL.getModel();
//I tried this after some help from internet
String classToGet = "";
if (chosenClass.matches("class12subjects")) {
classToGet = "XII";
} else if (chosenClass.matches("class11subjects")) {
classToGet = "XI";
}
Query = "select sd.rollno, name, sub1, sub2, sub3, sub4, sub5, sub6 "
+ "from stu_details sd join stu_marks sm "
+ "where sm.rollno = sd.rollno "
+ " and sd.optionalSubject='" + selectedGroup + "' and sd.class='"
+ classToGet + "';";
rs = st.executeQuery(Query);
i = 0;
while (rs.next()) {
tableModel.addRow(new Object[]{
rs.getString("rollno"),
rs.getString("name"),
rs.getString("sub1"),
rs.getString("sub2"),
rs.getString("sub3"),
rs.getString("sub4"),
rs.getString("sub5"),
rs.getString("sub6")});
//tableModel.setValueAt(1, 1, 4);
//When this is written, i am able to see 1 row in the output and then an array index out of exception
System.out.println(rs.getString("rollno")
+ rs.getString("name")
+ rs.getString("sub1")
+ rs.getString("sub2")
+ rs.getString("sub3")
+ rs.getString("sub4")
+ rs.getString("sub5")
+ rs.getString("sub6"));
}
}
I am able to print all the details in the output panel by using the System.out.println. But it is not getting added into the table.
As you can see the exception near //tableModel.setValueAt(1, 1, 4); i.e., array index out of bound with one row (zero th row) being displayed. I feel the rows are being added and then being deleted some how. I am not able figure it out. Can some one help me in this regard?
答案 0 :(得分：0)
我不太确定您要完成什么，因为您的代码段并未显示所有必要的数据。您的问题实际上是2个问题，如何在表格中添加一行以及如何打印表格的内容。 随附的代码是我编写的用于完成其他目的的方法，该方法已经过编辑，以删除多余的材料并使表通用。它将创建一个包含5列和6行数据的表，该表可以添加或删除行，并使用System.out.println（…。）打印出每行所有元素的内容。作为单独的行。 我希望这个对你有用。 将代码导入到IDE中，您可以根据需要进行编译，执行和编辑。 米切尔（R. Mitchell）
import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.table.DefaultTableModel;
import javax.swing.table.TableColumn;
import javax.swing.table.TableColumnModel;
class ModelJTable extends JFrame {
/**
* This application will create a table with 5 columns (0 to 4) and 6 rows
* (0 to 5). It will allow the removal of any or all rows individually. It
* will add row(s) as determined by commenting/uncommenting code. It will
* print the contents of all of the displayed rows as individual lines.
* That is:
* line 0, column 0 (line feed) line 0, column 1 (line feed) etc. Some of
* the comments are probably not applicable and most were for my
* information when I wrote the app.
*/
/**
* class variables
*/
public DefaultTableModel model;
public JTable table;
/**
* Table rows redefined to match column names. Not required. Automatically
* appends nulls.
*/
String[] rowZero = {"R0-C0", "R0-C1", "R0-C2", "R0-C3", "R0-C4"};
String[] rowOne = {"R1-C0", "R1-C1", "R1-C2", "R1-C3", "R1-C4"};
String[] newRow; // undefined String[]
public ModelJTable() {
super();
/**
* Redefined column names.
*/
model = new DefaultTableModel();
model.addColumn("Column 0");
model.addColumn("Column 1");
model.addColumn("Column 2");
model.addColumn("Col 3");
model.addColumn("Col 4");
/**
* moved to class variable to demonstrate that the row entry can be
* defined as a class variable. String[] rowZero = {"R0-C0", "R0-C1",
* "R0-C2", "R0-C3", "R0C4"};
*/
// model.addRow(socrates);
model.addRow(rowZero);
/**
* moved to class variable to demonstrate that the row entry can be
* defined as a class variable. String[] rowOne = {"R1-C0", "R1-C1",
* "R1-C2", "R1-C3", "R1-C4"};
*/
model.addRow(rowOne);
String[] rowTwo = {"R2-C0", "R2-C1", "R2-C2", "R2-C3", "R2-C4"};
model.addRow(rowTwo);
String[] rowThree = {"R3-C0", "R3-C1", "R3-C2", "R3-C3", "R3-C4"};
model.addRow(rowThree);
String[] rowFour = {"R4-C0", "R4-C1", "R4-C2", "R4-C3", "R4-C4"};
model.addRow(rowFour);
String[] rowFive = {"R5-C0", "R5-C1", "R5-C2", "R5-C3", "R5-C4"};
model.addRow(rowFive);
/**
* emptyRow elements must be "" NOT "null" or any other string.
*/
// String[] emptyRow = {"", "", "", "", ""};
// model.addRow(emptyRow);
table = new JTable(model, (TableColumnModel) table);
TableColumn nameColumn = table.getColumnModel().getColumn(0);
nameColumn.setPreferredWidth(75);
TableColumn surNameColumn = table.getColumnModel().getColumn(1);
surNameColumn.setPreferredWidth(75);
TableColumn datesColumn = table.getColumnModel().getColumn(2);
datesColumn.setPreferredWidth(300);
TableColumn column4 = table.getColumnModel().getColumn(3);
column4.setPreferredWidth(30);
TableColumn column5 = table.getColumnModel().getColumn(4);
column5.setPreferredWidth(30);
JButton quitButton = new JButton("Quit");
quitButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent event) {
System.exit(0);
}
});
JButton printTableButton = new JButton("Print Table");
printTableButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent event) {
printFile(); // go to print file method
}
});
JButton addButton = new JButton("Add Row");
addButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent event) {
addNewRow();
}
});
JButton removeButton = new JButton("Remove Row");
removeButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent event) {
try {
model.removeRow(table.getSelectedRow());
} catch (Exception e) {
System.out.println("Nothing selected to remove.");
}
}
});
JPanel inputPanel = new JPanel();
inputPanel.add(quitButton);
inputPanel.add(printTableButton);
inputPanel.add(addButton);
inputPanel.add(removeButton);
JPanel southernPanel = new JPanel();
Container container = getContentPane();
container.add(inputPanel, BorderLayout.SOUTH);
container.add(southernPanel, BorderLayout.NORTH);
container.add(new JScrollPane(table), BorderLayout.CENTER);
setDefaultCloseOperation(EXIT_ON_CLOSE);
setSize(600, 600);
this.setUndecorated(true);
this.setResizable(false);
this.setLocationRelativeTo(null);
setVisible(true);
} // end of public ModelJTable() method
public void addNewRow() {
String[] addRow = {"New Row", "New Row", "New Row", "New Row",
"New Row"};
model.addRow(addRow);
}
/**
* public static void main(String args[]) { new ModelJTable(); } // end of
* main()
*/
public static void main(String args[]) {
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new ModelJTable().setVisible(true);
}
});
}
public void printFile() {
int rowCount = model.getRowCount(); // rowCount is decimal (1 to X)
int columnNumber = 0;
int rowNumber = 0;
String rowElement = "";
// System.out.println("Printing the rows of the table.");
// System.out.println("rowCount = " + rowCount);
/**
* Row numbering is zero to X. rowCount is decimal (1 to X).
*/
int elementNumber = 0; // initialize elementNumber
/**
* There are 5 elements (0 to 4) in each row. There are rowCount rows (1
* to rowCount) in the table. Therefore there are rowCount * 5 elements
* to be printed.
*/
int endOfLoop = 5 * rowCount;
//System.out.println("Number of elements in the table = " + endOfLoop);
for (int i = 0; i < endOfLoop; i++) {
System.out.println(model.getValueAt(rowNumber, elementNumber)
.toString());
if (elementNumber == 4) {
elementNumber = 0;
rowNumber++;
} else {
elementNumber++;
}
}
}
} // end of class ModelJTable