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Created by Dr. Xi on March 02, 2011 11:39:18    Last update: March 09, 2011 12:19:30
Some peculiarities about Java PrintWriter: PrintWriter never throws any exceptions. From JavaDoc : Methods in this class never throw I/O exceptions, although some of its constructors may. The client may inquire as to whether any errors have occurred by invoking checkError(). When error occurs, you'll never know anything more than that it occured, because checkError returns boolean. When a character is out of the range of the character encoding of the PrintWriter, it prints a question mark (?). But this is not an error. Test code: import java.io.*; public class TestPrintWri... Latin1 test result: java TestPrintWriter iso-8859-1 | od -bc 000000... UTF-8 test result: java TestPrintWriter utf-8 | od -bc 0000000 141... Also, the constructor throws a FileNotFoundException when you try to write to a...
Created by nogeek on November 11, 2010 00:26:08    Last update: November 11, 2010 00:29:43
This one is even more weird: it worked on Windows but failed on Linux, using default tools JDK1.6.0_20 on both. The exception thrown was: java.lang.RuntimeException: Invalid conversion fro... And the stack trace: java.lang.RuntimeException: Invalid conversion fro... This was the XSL used: <?xml version="1.0" encoding="ISO-8859-1"?> <xs... The problem was , DateUtil.java had two getDate methods, one taking long parameter, the other taking a String parameter. And Java's XSLT get confused about which one to use: import java.util.Date; import java.text.SimpleD...
Created by Dr. Xi on October 26, 2010 16:07:40    Last update: October 26, 2010 16:07:40
This is a more generic version, which can be expanded to accommodate additional file signatures. import java.io.*; import java.util.*; pu...
Created by Fang on August 10, 2010 21:37:36    Last update: October 25, 2010 20:18:47
The tags <fmt:formatNumber> Format a numeric value as number , currency or percentage - controlled by the type attribute (defaults to number if type is missing). Syntax: <fmt:formatNumber value="numericValue" [type="... Attributes: Name Dynamic? Type Description value true String or Number Numeric value to be formatted. type true String Specifies whether the value is to be formatted as number, currency, or percentage. pattern true String Custom formatting pattern, must follow the pattern syntax specified by the class java.text.DecimalFormat . currencyCode true String ISO 4217 currency code. Applied only when formatting currencies (i.e. if type is equal to "currency"); ignored otherwise. currencySymbol true String Currency symbol. Applied only when formatting currencies (i.e. if type is equal to "currency"); ignored otherwise. It is used only when currencyCode is...
Created by Dr. Xi on July 29, 2010 18:46:57    Last update: July 29, 2010 18:48:15
This is an example of using java.beans.XMLEncoder and java.beans.XMLDecoder to serialize/deserialize Java objects to XML. Java code TestXMLEncoder.java: import java.io.*; import java.beans.XMLEncoder;... SimpleBean.java: public class SimpleBean { private String na... CompositeBean.java: public class CompositeBean { private Simple... NotABean.java: public class NotABean { private String name... Test Output By default, only Java beans can be serialized using XMLEncoder . Exception occurs when you try to deserialize an object which is not a Java bean. Errors actually occur when you try to serialize, but they are ignored. As a result, an XML file is generated by the serialization but the file is useless! Console output: C:\>java TestXMLEncoder Testing simple bean ... simplebean.xml: <?xml version="1.0" encoding="UTF-8"?> <java v... compositebean.xml: <?xml version="1.0" encoding="UTF-8"?> <java v... nodefault.xml: <?xml version="1.0" encoding="UTF-8"?> <java v......
Created by Fang on April 04, 2010 04:12:14    Last update: July 21, 2010 14:52:58
The tags <c:if> The <c:if> tag may be used with or without body content: <!-- Without body content, used to export vari... In my opinion, the version without body content is pretty much useless (the <c:set> tag is a lot more meaningful for this purpose). If body content exists, it is inserted into the page if the testCondition is true . Optional attributes var and scope may be specified. If var is specified, a variable whose name is the value of var is exported to the associated scope ( pageScope if no scope is specified). The type of the exported variable is Boolean and its value is the value of the testCondition . <c:choose>, <c:when>, <c:otherwise> These tags imitate the Java control structure if...else...
Created by Dr. Xi on January 07, 2010 20:02:00    Last update: January 07, 2010 20:07:19
If all you want is a quick way to format some numbers, a sample program speaks more words than the full documentation. import java.text.DecimalFormat; public clas... Use String.format : public class TestFormat { public static voi...
Created by Dr. Xi on October 18, 2009 04:25:25    Last update: October 18, 2009 04:25:25
start python with python -v import django and print version: Type "help", "copyright", "credits" or "license" f...
Created by Dr. Xi on June 06, 2009 19:21:57    Last update: June 06, 2009 19:21:57
import time import random # Python sleep...
Created by Dr. Xi on October 23, 2008 03:54:04    Last update: October 23, 2008 03:57:44
Add validator plugin in struts-config.xml <struts-config> . . . ... Set validate="true" on action form <struts-config> <!-- ========== Form Bean De... Add validation rules in validation.xml <?xml version='1.0' encoding='windows-1252'?> <... If you override validate , make sure super.validate is called. package com.example; import javax.servlet.h... Read the documentation: http://struts.apache.org/1.2.4/userGuide/dev_validator.html
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