我在使用Netbeans 7.2的JAVA中使用文本字段自动计算时遇到问题
我的问题是我是否会在文本字段中输入数值,即(入场费,月费,交通费等)自动添加,然后在文本字段中输入数值,即(会费)自动从上述自动添加中减去在单击提交按钮之前,在数据库中插入总值,以便在单击提交按钮之前如何在文本字段(总计)中获得这些数值的结果。
请检查快照:
image http://s14.postimage.org/95zxgp575/image.jpg
我的源代码:
try
{
String insrt = "Insert into fee (admission, monthly, transport, dues, total) values (?, ?, ?, ?, ?)";
PreparedStatement pstmt = conn.prepareStatement(insrt);
pstmt.setString(1, adm_fee.getText());
pstmt.setString(2, mnth_fee.getText());
pstmt.setString(3, trnsprt_fee.getText());
pstmt.setString(4, dues_fee.getText());
pstmt.setString(5, total_fee.getText());
pstmt.executeUpdate();
JOptionPane.showMessageDialog(null,"Record successfully inserted");
}
catch (Exception exp)
{
JOptionPane.showMessageDialog(null, exp);
}
答案 0 :(得分:5)
我建议使用DocumentFilter
这样我们就可以用1石头杀死2只鸟。
1)我们需要过滤输入到JTextField
的内容,以确保我们的计算不会出错
2)我们需要动态更新总数,即添加/删除更多数字。
以下是我使用DocumentFilter
制作的示例,您将看到每次输入新数字/添加到JTextField
时,总计字段都会更新(s)(也不允许字母字符等只有数字):
import java.awt.GridLayout;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
import javax.swing.text.AbstractDocument;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.DocumentFilter;
import javax.swing.text.DocumentFilter.FilterBypass;
public class DocumentFilterOnTheFlyCalculation {
public DocumentFilterOnTheFlyCalculation() {
createAndShowGui();
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
new DocumentFilterOnTheFlyCalculation();
}
});
}
private void createAndShowGui() {
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new GridLayout(4, 2));
JLabel label1 = new JLabel("Add:");
final JTextField jtf1 = new JTextField();
JLabel label2 = new JLabel("Add:");
final JTextField jtf2 = new JTextField();
JLabel label3 = new JLabel("Subtract:");
final JTextField jtf3 = new JTextField();
JLabel totalLabel = new JLabel("Total:");
final JTextField totalField = new JTextField("0");
totalField.setEditable(false);
DocumentFilter df = new DocumentFilter() {
@Override
public void insertString(FilterBypass fb, int i, String string, AttributeSet as) throws BadLocationException {
if (isDigit(string)) {
super.insertString(fb, i, string, as);
calcAndSetTotal();
}
}
@Override
public void remove(FilterBypass fb, int i, int i1) throws BadLocationException {
super.remove(fb, i, i1);
calcAndSetTotal();
}
@Override
public void replace(FilterBypass fb, int i, int i1, String string, AttributeSet as) throws BadLocationException {
if (isDigit(string)) {
super.replace(fb, i, i1, string, as);
calcAndSetTotal();
}
}
private boolean isDigit(String string) {
for (int n = 0; n < string.length(); n++) {
char c = string.charAt(n);//get a single character of the string
//System.out.println(c);
if (!Character.isDigit(c)) {//if its an alphabetic character or white space
return false;
}
}
return true;
}
void calcAndSetTotal() {
int sum = 0;
if (!jtf1.getText().isEmpty()) {
sum += Integer.parseInt(jtf1.getText());//we must add this
}
if (!jtf2.getText().isEmpty()) {
sum += Integer.parseInt(jtf2.getText());//we must add this
}
if (!jtf3.getText().isEmpty()) {
sum -= Integer.parseInt(jtf3.getText());//we must subtract this
}
totalField.setText(String.valueOf(sum));
}
};
((AbstractDocument) (jtf1.getDocument())).setDocumentFilter(df);
((AbstractDocument) (jtf2.getDocument())).setDocumentFilter(df);
((AbstractDocument) (jtf3.getDocument())).setDocumentFilter(df);
frame.add(label1);
frame.add(jtf1);
frame.add(label2);
frame.add(jtf2);
frame.add(label3);
frame.add(jtf3);
frame.add(totalLabel);
frame.add(totalField);
frame.pack();
frame.setVisible(true);
}
}
答案 1 :(得分:2)
如果您不需要针对每次击键进行更新,则alternate approach会同时使用FocusListener
和PropertyChangeListener
至update()
作为更改累计。
答案 2 :(得分:0)
enter image description here您可以使用MouseEntered事件在jtextfield中自动显示计算值,如代码所示
lookup = {}
for each([item_number, value])) {
if (lookup[value]) {
throw error ('Items ' + item_number + ' and ' + lookup[value] + ' are identical')
} else {
lookup[value] = item_number
}