This is a utility to convert a byte array to hex string, and to convert a hex string back to the original. To convert a String to hex, you must call String.getBytes() first. The utility does not pretend to know your string encoding. public class StringHexUtil { public static ... This also works: String binaryToHex(byte[] data) { StringBui...

To implement a JSP custom tag with dynamic attributes (for example, to pass-thru arbitrary attributes not handled by the JSP tag): Set the dynamic-attributes element to true in the TLD: <tag> <name>mark</name> <tag-class>c... The tag handler must implement javax.servlet.jsp.tagext.DynamicAttributes : package com.example.jsp; import java.io.*; ...

This is an Android app that dumps any binarized xml file as plain text - to the sdcard on the device or emulator. build.xml : <?xml version="1.0" encoding="UTF-8"?> <project... AndroidManifest.xml <?xml version="1.0" encoding="utf-8"?> <man... res/layout/main.xml <?xml version="1.0" encoding="utf-8"?> <Lin... res/values/strings.xml : <?xml version="1.0" encoding="utf-8"?> <res... src/com/android/xmltool/DumpXml.java package com.android.xmltool; import java.ut... Screenshot Pre-built APK can be downloaded from: http://code.google.com/p/android-binxml-dump/

A pair of C functions convert between an Internet address and a string (ASCII): #include <arpa/inet.h> /* * Returns a poin... However , these functions do not support IPv6. The new pair is: #include <arpa/inet.h> /* Convert a Internet ad... Examples: #include <sys/socket.h> #include <netinet/in.h>...

This is an example that uses dynamic proxies to trace method calls (in logging) and print out elapsed times for them. Because dynamic proxies can only be generated for interfaces, the service classes must be implemented with interface-implementation pairs. Create services A and B. A.java : public interface A { public void service1()... AImpl.java : import java.util.Random; public class AImpl... B.java : public interface B { public void service1()... BImpl.java : public class BImpl implements B { public vo... The call trace proxy: import java.lang.reflect.*; class TraceProx... The performance proxy: import java.lang.reflect.*; class Performan... The service factory: import java.lang.reflect.*; public class Se... The test class: public class Test { public static void main... The output: Entering AImpl.service1 Entering BImpl.service1... The above example has no information...

Class.isAssignableFrom() returns true only if the argument is identical to the current class or is a subclass of the current class. Example: public class AssignableTest { public static... Even though an int can be assigned to an Integer and vice versa through auto-boxing, isAssignableFrom returns false when called one way or the other. // This compiles and runs. But isAssignableFrom() ...

The String.format() method provides versatile formatting capabilities. This tutorial tries to present these capabilities in a accessible manner. The format string A format string can contain zero, one, or more format specifiers . The general form of a format specifier is: %[argument_index$] [flags] [width] [.precision]co... where things in square brackets are optional, and conversion is a character indicating the conversion to be applied to the corresponding variable value. The only required characters in the format specifier is the percent sign % and the conversion character. A simple example: public static void simpleFormat() { System.out... The Argument index The argument index is specified by a number, terminated by the dollar sign $ . The same argument may be repeated multiple times in a format string. Unindexed...

Some methods to create an array in Java: With literal initialization. // array of strings String[] dogs = { "Chihuah... With array constructor (array allocated by not the elements). // create a byte array byte[] buffer = new byte... Anonymous array to be used as a parameter in method invocation String.format("Hello %s, %s, %s!", new Object[] { ...

package com.demo.io; import java.io.*; ...

A task that a Java developer does so frequently is to find out where a certain class can be found - to resolve compilation errors, classpath issues, or version conflicts of the same class introduced by multiple class loaders. A long while back I wrote a simple Perl script to perform the task. Later I was informed that there are Swing based Jar Browser and Jars Browser . Then, there are a couple of shell one-liners: # one liner 1 find -name "*.jar" -print0 | xarg... But all of them share the same problem: if a class is in a jar nested in another jar, it cannot be found. Such is the case for a class inside a jar under the WEB-INF/lib directory of a...