formtext_formtextnum.html
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<TITLE>Creating a Text Field to Display and Edit a Number
(Java Developers Almanac Example)
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<META CONTENT="Patrick Chan" NAME="AUTHOR">
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<B><A HREF="../javax.swing.text/pkg.html#JFormattedTextField">JFormattedTextField</A></B><font color="#666666" SIZE="-2">
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<h3>
e994.
Creating a Text Field to Display and Edit a Number</h3>
This example uses a <code>JFormattedTextField</code> to allow the display and
editing of a number. By default, when the component loses the focus
and the modified value is a valid date, the modified value is
saved. Otherwise, if the modified value is not a valid date, the
modified value is discarded and the old value is displayed.
<pre>
// Support an integer number; if a decimal point is typed,
// the decimal point and all following characters are discarded
JFormattedTextField tft1 = new JFormattedTextField(NumberFormat.getIntegerInstance());
tft1.setValue(new Integer(<font color="#0066ff"><i>123</i></font>));
// Retrieve the value from the text field
Integer intValue = (Integer)tft1.getValue();
// Support a decimal number with one digit following the decimal point;
// if more digits after the decimal point is typed, the value is rounded to one decimal place
JFormattedTextField tft2 = new JFormattedTextField(new DecimalFormat("#.0"));
tft2.setValue(new Float(<font color="#0066ff"><i>123.4F</i></font>));
// Retrieve the value from the text field
Float floatValue = (Float)tft2.getValue();
</pre>
By default, if the type of the value is not one of <code>Byte</code>,
<code>Short</code>, <code>Integer</code>, <code>Long</code> , <code>Float</code>, or <code>Double</code>, the
object is automatically converted to a <code>Double</code> after it has been
edited. To prevent this, a custom formatter must be used. This example
demonstrates this by using a <code>BigDecimal</code> object.
<pre>
// Support a decimal number with arbitrary number of decimal digits.
// Actually, this isn't technically possible using DecimalFormat;
// the best that we can do is to specify lots of #'s
JFormattedTextField tft3 = new JFormattedTextField(new BigDecimal(<font color="#0066ff"><i>"123.4567"</i></font>));
DefaultFormatter fmt = new NumberFormatter(new DecimalFormat("#.0###############"));
fmt.setValueClass(tft3.getValue().getClass());
DefaultFormatterFactory fmtFactory = new DefaultFormatterFactory(fmt, fmt, fmt);
tft3.setFormatterFactory(fmtFactory);
// Retrieve the value from the text field
BigDecimal bigValue = (BigDecimal)tft3.getValue();
</pre>
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Related Examples
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e995. <a class="eglink" href="formtext_FormTextDate.html?l=rel">
Creating a Text Field to Display and Edit a Date
</a>
<br>
e996. <a class="eglink" href="formtext_FormTextMask.html?l=rel">
Creating a Text Field to Display and Edit a Phone Number
</a>
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See also:
<a class="eglink" href="/egs/javax.swing.text/pkg.html?l=rel#Actions%20and%20Key%20Bindings">
Actions and Key Bindings
</a>
<a class="eglink" href="/egs/javax.swing.text/pkg.html?l=rel#Caret%20and%20Selection">
Caret and Selection
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<a class="eglink" href="/egs/javax.swing.text/pkg.html?l=rel#Events">
Events
</a>
<a class="eglink" href="/egs/javax.swing.text/pkg.html?l=rel#JEditorPane">
JEditorPane
</a>
<a class="eglink" href="/egs/javax.swing.text/pkg.html?l=rel#JTextArea">
JTextArea
</a>
<a class="eglink" href="/egs/javax.swing.text/pkg.html?l=rel#JTextComponent">
JTextComponent
</a>
<a class="eglink" href="/egs/javax.swing.text/pkg.html?l=rel#JTextField">
JTextField
</a>
<a class="eglink" href="/egs/javax.swing.text/pkg.html?l=rel#JTextPane">
JTextPane
</a>
<a class="eglink" href="/egs/javax.swing.text/pkg.html?l=rel#Styles">
Styles
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