我有一个最大小数位数为 6 的 JSpinner
。因此,当我输入 1.1234567
时,它会四舍五入为 1.123457
。
但我的要求是,当用户以自由文本形式输入值时,我想禁用舍入并将值设置为微调器(1.1234567
)。但是,如果用户单击微调器箭头按钮,它可以被舍入。
最佳答案
该值通常由 JSpinner
的编辑器格式化。您更改编辑器格式化显示值的方式,这将使实际模型值保持不变
编辑器通常由 JFormattedTextField
支持,如果能够捕获它并配置它就好了...
可能有几种方法可以做到这一点,但我选择使用 NumberFormat
,因为我知道如何控制小数位数和舍入模式
首先,我们需要实现一个JFormattedTextField.AbstractFormatter
public class NumberFormatFormatter extends DefaultFormatter {
private NumberFormat format;
public NumberFormatFormatter(NumberFormat format) {
this.format = format;
}
@Override
public Object stringToValue(String string) throws ParseException {
System.out.println("stringToValue: " + string);
return format.parse(string);
}
@Override
public String valueToString(Object value) throws ParseException {
String text = format.format(value);
System.out.println("valueToString: " + value + "; " + text);
return text;
}
}
然后将其包装在 AbstractFormatterFactory
NumberFormat numberInstance = NumberFormat.getNumberInstance();
numberInstance.setMaximumFractionDigits(6);
numberInstance.setMinimumFractionDigits(0);
numberInstance.setRoundingMode(RoundingMode.DOWN);
JFormattedTextField.AbstractFormatter format = new NumberFormatFormatter(numberInstance);
DefaultFormatterFactory dff = new DefaultFormatterFactory(format);
然后我们配置 JSpinner
并创建一个新的 NumberEditor
来满足我们的需要
JSpinner spinner = new JSpinner(new SpinnerNumberModel());
JSpinner.NumberEditor editor = new JSpinner.NumberEditor(spinner, "0.0#####");
JFormattedTextField textField = editor.getTextField();
textField.setFormatterFactory(dff);
textField.setColumns(10);
spinner.setEditor(editor);
不要忘记将编辑器应用于 JSpinner
;)。
这可能看起来很多(我当然这么认为),但是将它包装到您自己的编辑器类的实现中并不需要太多,该编辑器类只是将 NumberFormat
作为参数,因为一个想法。
这种方法将“显示”留给了编辑器,但不会影响模型中的基础值,因此,如果您输入 1.123456789
,模型仍将返回 1.123456789
,但它会显示 1.123456
查看 How to Use Formatted Text Fields 和 How to Use Spinners 了解更多详情
import java.awt.EventQueue;
import java.awt.GridBagLayout;
import java.math.RoundingMode;
import java.text.NumberFormat;
import java.text.ParseException;
import javax.swing.JFormattedTextField;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JSpinner;
import javax.swing.SpinnerNumberModel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.text.DefaultFormatter;
import javax.swing.text.DefaultFormatterFactory;
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
public TestPane() {
NumberFormat numberInstance = NumberFormat.getNumberInstance();
numberInstance.setMaximumFractionDigits(6);
numberInstance.setMinimumFractionDigits(0);
numberInstance.setRoundingMode(RoundingMode.DOWN);
JFormattedTextField.AbstractFormatter format = new NumberFormatFormatter(numberInstance);
DefaultFormatterFactory dff = new DefaultFormatterFactory(format);
JSpinner spinner = new JSpinner(new SpinnerNumberModel());
JSpinner.NumberEditor editor = new JSpinner.NumberEditor(spinner, "#0.######");
JFormattedTextField textField = editor.getTextField();
textField.setFormatterFactory(dff);
textField.setColumns(10);
spinner.setEditor(editor);
setLayout(new GridBagLayout());
spinner.setValue(1.1234567d);
add(spinner);
}
public class NumberFormatFormatter extends DefaultFormatter {
private NumberFormat format;
public NumberFormatFormatter(NumberFormat format) {
this.format = format;
}
@Override
public Object stringToValue(String string) throws ParseException {
System.out.println("stringToValue: " + string);
return format.parse(string);
}
@Override
public String valueToString(Object value) throws ParseException {
String text = format.format(value);
System.out.println("valueToString: " + value + "; " + text);
return text;
}
}
}
}
关于java - 如何在 JSpinner 中禁用值的舍入,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/31065702/