问题
I would like to format a float number as a percent-value with JFormattedTextField that allows inputs from 0 to 100 percent (converted to 0.0f-1.0f), always shows the percent sign and disallows any invalid characters.
Now I have experimented a bit with NumberFormat.getPercentInstance() and the NumberFormatter attributes but without success.
Is there a way to create a JFormattedTextField that obeys to these rules with the standard classes? Or do I have to implement my own NumberFormatter?
That's what I have so far (no way to input 100%, entering a 0 breaks it completly):
public class MaskFormatterTest {
public static void main(String[] args) throws Exception {
JFrame frame = new JFrame("Test");
frame.setLayout(new BorderLayout());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
NumberFormat format = NumberFormat.getPercentInstance();
NumberFormatter formatter = new NumberFormatter(format);
formatter.setMaximum(1.0f);
formatter.setMinimum(0.0f);
formatter.setAllowsInvalid(false);
formatter.setOverwriteMode(true);
JFormattedTextField tf = new JFormattedTextField(formatter);
tf.setColumns(20);
tf.setValue(0.56f);
frame.add(tf);
frame.pack();
frame.setVisible(true);
}
}
回答1:
Ok, I've made it. The solution is far from simple, but at least it does exactly what I want. Except for returning doubles instead of floats. One major limitation is that it does not allow fraction digits, but for now I can live with that.
import java.awt.BorderLayout;
import java.text.NumberFormat;
import java.text.ParseException;
import javax.swing.JComponent;
import javax.swing.JFormattedTextField;
import javax.swing.JSpinner;
import javax.swing.SpinnerNumberModel;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.DefaultFormatterFactory;
import javax.swing.text.DocumentFilter;
import javax.swing.text.NavigationFilter;
import javax.swing.text.NumberFormatter;
import javax.swing.text.SimpleAttributeSet;
import javax.swing.text.Position.Bias;
public class JPercentField extends JComponent {
private static final double MIN_VALUE = 0.0d;
private static final double MAX_VALUE = 1.0d;
private static final double STEP_SIZE = 0.01d;
private static final long serialVersionUID = -779235114254706347L;
private JSpinner spinner;
public JPercentField() {
initComponents();
initLayout();
spinner.setValue(MIN_VALUE);
}
private void initComponents() {
SpinnerNumberModel model = new SpinnerNumberModel(MIN_VALUE, MIN_VALUE, MAX_VALUE, STEP_SIZE);
spinner = new JSpinner(model);
initSpinnerTextField();
}
private void initSpinnerTextField() {
DocumentFilter digitOnlyFilter = new PercentDocumentFilter(getMaximumDigits());
NavigationFilter navigationFilter = new BlockLastCharacterNavigationFilter(getTextField());
getTextField().setFormatterFactory(
new DefaultFormatterFactory(new PercentNumberFormatter(createPercentFormat(), navigationFilter,
digitOnlyFilter)));
getTextField().setColumns(6);
}
private int getMaximumDigits() {
return Integer.toString((int) MAX_VALUE * 100).length();
}
private JFormattedTextField getTextField() {
JSpinner.NumberEditor jsEditor = (JSpinner.NumberEditor) spinner.getEditor();
JFormattedTextField textField = jsEditor.getTextField();
return textField;
}
private NumberFormat createPercentFormat() {
NumberFormat format = NumberFormat.getPercentInstance();
format.setGroupingUsed(false);
format.setMaximumIntegerDigits(getMaximumDigits());
format.setMaximumFractionDigits(0);
return format;
}
private void initLayout() {
setLayout(new BorderLayout());
add(spinner, BorderLayout.CENTER);
}
public double getPercent() {
return (Double) spinner.getValue();
}
public void setPercent(double percent) {
spinner.setValue(percent);
}
private static class PercentNumberFormatter extends NumberFormatter {
private static final long serialVersionUID = -1172071312046039349L;
private final NavigationFilter navigationFilter;
private final DocumentFilter digitOnlyFilter;
private PercentNumberFormatter(NumberFormat format, NavigationFilter navigationFilter,
DocumentFilter digitOnlyFilter) {
super(format);
this.navigationFilter = navigationFilter;
this.digitOnlyFilter = digitOnlyFilter;
}
@Override
protected NavigationFilter getNavigationFilter() {
return navigationFilter;
}
@Override
protected DocumentFilter getDocumentFilter() {
return digitOnlyFilter;
}
@Override
public Class<?> getValueClass() {
return Double.class;
}
@Override
public Object stringToValue(String text) throws ParseException {
Double value = (Double) super.stringToValue(text);
return Math.max(MIN_VALUE, Math.min(MAX_VALUE, value));
}
}
/**
* NavigationFilter that avoids navigating beyond the percent sign.
*/
private static class BlockLastCharacterNavigationFilter extends NavigationFilter {
private JFormattedTextField textField;
private BlockLastCharacterNavigationFilter(JFormattedTextField textField) {
this.textField = textField;
}
@Override
public void setDot(FilterBypass fb, int dot, Bias bias) {
super.setDot(fb, correctDot(fb, dot), bias);
}
@Override
public void moveDot(FilterBypass fb, int dot, Bias bias) {
super.moveDot(fb, correctDot(fb, dot), bias);
}
private int correctDot(FilterBypass fb, int dot) {
// Avoid selecting the percent sign
int lastDot = Math.max(0, textField.getText().length() - 1);
return dot > lastDot ? lastDot : dot;
}
}
private static class PercentDocumentFilter extends DocumentFilter {
private int maxiumDigits;
public PercentDocumentFilter(int maxiumDigits) {
super();
this.maxiumDigits = maxiumDigits;
}
@Override
public void insertString(FilterBypass fb, int offset, String text, AttributeSet attrs)
throws BadLocationException {
// Mapping an insert as a replace without removing
replace(fb, offset, 0, text, attrs);
}
@Override
public void remove(FilterBypass fb, int offset, int length) throws BadLocationException {
// Mapping a remove as a replace without inserting
replace(fb, offset, length, "", SimpleAttributeSet.EMPTY);
}
@Override
public void replace(FilterBypass fb, int offset, int length, String text, AttributeSet attrs)
throws BadLocationException {
int replaceLength = correctReplaceLength(fb, offset, length);
String cleanInput = truncateInputString(fb, filterDigits(text), replaceLength);
super.replace(fb, offset, replaceLength, cleanInput, attrs);
}
/**
* Removes all non-digit characters
*/
private String filterDigits(String text) throws BadLocationException {
StringBuilder sb = new StringBuilder(text);
for (int i = 0, n = sb.length(); i < n; i++) {
if (!Character.isDigit(text.charAt(i))) {
sb.deleteCharAt(i);
}
}
return sb.toString();
}
/**
* Removes all characters with which the resulting text would exceed the maximum number of digits
*/
private String truncateInputString(FilterBypass fb, String filterDigits, int replaceLength) {
StringBuilder sb = new StringBuilder(filterDigits);
int currentTextLength = fb.getDocument().getLength() - replaceLength - 1;
for (int i = 0; i < sb.length() && currentTextLength + sb.length() > maxiumDigits; i++) {
sb.deleteCharAt(i);
}
return sb.toString();
}
private int correctReplaceLength(FilterBypass fb, int offset, int length) {
if (offset + length >= fb.getDocument().getLength()) {
// Don't delete the percent sign
return offset + length - fb.getDocument().getLength();
}
return length;
}
}
}
回答2:
1) consider using JSpinner instead of JFormattedTextField because there you can set SpinnerNumberModel for initial values
from API
Integer value = new Integer(50);
Integer min = new Integer(0);
Integer max = new Integer(100);
Integer step = new Integer(1);
and with simple hack for JSpinner (with SpinnerNumberModel) it doesn't allows another input as Digits, otherwise is there possible input any of Chars
2) for JFormattedTextField you have to implements
- DocumentListener
- Document
and of both cases for JFormattedTextField you have to write workaround for catch if value is less or more than required range ...
EDIT:
.
.
not true at all, :-) you are so far from ... simple wrong :-), there is small mistake with your result, please look at this code
import java.awt.BorderLayout;
import java.text.NumberFormat;
import javax.swing.*;
import javax.swing.text.*;
public class TestDigitsOnlySpinner {
public static void main(String... args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
JFrame frame = new JFrame("enter digit");
JSpinner jspinner = makeDigitsOnlySpinnerUsingDocumentFilter();
frame.getContentPane().add(jspinner, BorderLayout.CENTER);
frame.getContentPane().add(new JButton("just another widget"), BorderLayout.SOUTH);
frame.pack();
frame.setVisible(true);
}
private JSpinner makeDigitsOnlySpinnerUsingDocumentFilter() {
JSpinner spinner = new JSpinner(new SpinnerNumberModel());
JSpinner.NumberEditor jsEditor = (JSpinner.NumberEditor) spinner.getEditor();
JFormattedTextField textField = jsEditor.getTextField();
final DocumentFilter digitOnlyFilter = new DocumentFilter() {
@Override
public void insertString(FilterBypass fb, int offset, String string, AttributeSet attr) throws BadLocationException {
if (stringContainsOnlyDigits(string)) {
super.insertString(fb, offset, string, attr);
}
}
@Override
public void remove(FilterBypass fb, int offset, int length) throws BadLocationException {
super.remove(fb, offset, length);
}
@Override
public void replace(FilterBypass fb, int offset, int length, String text, AttributeSet attrs) throws BadLocationException {
if (stringContainsOnlyDigits(text)) {
super.replace(fb, offset, length, text, attrs);
}
}
private boolean stringContainsOnlyDigits(String text) {
for (int i = 0; i < text.length(); i++) {
if (!Character.isDigit(text.charAt(i))) {
return false;
}
}
return true;
}
};
/*NumberFormat format = NumberFormat.getIntegerInstance();
format.setGroupingUsed(false);// or add the group chars to the filter
NumberFormat format = NumberFormat.getInstance();*/
NumberFormat format = NumberFormat.getPercentInstance();
format.setGroupingUsed(false);
format.setGroupingUsed(true);// or add the group chars to the filter
format.setMaximumIntegerDigits(10);
format.setMaximumFractionDigits(2);
format.setMinimumFractionDigits(5);
textField.setFormatterFactory(new DefaultFormatterFactory(new InternationalFormatter(format) {
private static final long serialVersionUID = 1L;
@Override
protected DocumentFilter getDocumentFilter() {
return digitOnlyFilter;
}
}));
return spinner;
}
});
}
}
回答3:
Imho https://docs.oracle.com/javase/tutorial/uiswing/components/formattedtextfield.html gives a pretty good example (see section "Specifying Formatters and Using Formatter Factories").
The key is to use a Percent Format to display values and a custom NumberFormatter to edit values. This approach also allows the use of fraction digits.
// create a format for displaying percentages (with %-sign)
NumberFormat percentDisplayFormat = NumberFormat.getPercentInstance();
// create a format for editing percentages (without %-sign)
NumberFormat percentEditFormat = NumberFormat.getNumberInstance();
// create a formatter for editing percentages - input will be transformed to percentages (eg. 50 -> 0.5)
NumberFormatter percentEditFormatter = new NumberFormatter(percentEditFormat) {
private static final long serialVersionUID = 1L;
@Override
public String valueToString(Object o) throws ParseException {
Number number = (Number) o;
if (number != null) {
double d = number.doubleValue() * 100.0;
number = new Double(d);
}
return super.valueToString(number);
}
@Override
public Object stringToValue(String s) throws ParseException {
Number number = (Number) super.stringToValue(s);
if (number != null) {
double d = number.doubleValue() / 100.0;
number = new Double(d);
}
return number;
}
};
// set allowed range
percentEditFormatter.setMinimum(0D);
percentEditFormatter.setMaximum(100D);
// create JFormattedTextField
JFormattedTextField field = new JFormattedTextField(
new DefaultFormatterFactory(
new NumberFormatter(percentDisplayFormat),
new NumberFormatter(percentDisplayFormat),
percentEditFormatter));
来源：https://stackoverflow.com/questions/7569929/jformattedtextfield-to-format-percent-numbers