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Created by Dr. Xi on June 21, 2011 15:54:00
Last update: June 22, 2011 11:33:09
Demo code for CSV parsing with SuperCSV parser .
Java code:
import java.io.*;
import java.util.List;
imp...
Test with a simple CSV file:
psmith01,CLASS2B,Peter Smith 1,YEAR2,1,N,ADVANCED,...
The parser worked correctly:
Line 1 has 11 values:
|psmith01|
|CLASS2B|...
Test with a more complicated CSV file:
"psmith01 abc", "CLASS2B " , " Peter...
The parser messed up on all three lines:
Line 1 has 5 values:
|psmith01 abc|
|CLASS...
Using two lines input:
"psmith01 abc", "CLASS2B " , " Peter...
It generates an exception:
Line 1 has 5 values:
|psmith01 abc|
|CLASS...
Add a new line in item two:
"One", "Two
", "Three"
Result:
Line 2 has 3 values:
|One|
|Two
|
|...
Created by Dr. Xi on June 22, 2011 07:12:02
Last update: June 22, 2011 11:32:02
Demo code for CSV parsing with OstermillerUtils .
Java code:
import java.io.*;
import java.util.List;
imp...
Test with a simple CSV file:
psmith01,CLASS2B,Peter Smith 1,YEAR2,1,N,ADVANCED,...
The parser worked correctly:
Line 1 has 11 values:
|psmith01|
|CLASS2B|...
Test with a more complicated CSV file:
"psmith01 abc", "CLASS2B " , " Peter...
The parser messed up on all three lines:
Line 1 has 6 values:
|psmith01 abc|
| "CLA...
Putting a space before the first quote:
"Smith, Jack","210-345-8888"
It dismissed the quotes:
Line 1 has 3 values:
| "Smith|
| Jack"|
...
Add a new line in item two:
"One", "Two
", "Three"
Result:
Line 1 has 2 values:
|One|
| "Two|
...
Created by Dr. Xi on June 16, 2011 14:23:44
Last update: June 16, 2011 14:25:04
This example shows how a service implementation can be loaded with a URLClassLoader .
The files.
HelloService.java :
public interface HelloService {
public void...
HelloServiceImpl.java :
public class HelloServiceImpl implements HelloServ...
ServiceFactory.java uses URLClassLoader to load the service implementation:
import java.io.*;
import java.net.*;
pub...
Test.java :
import java.io.*;
import java.net.*;
pub...
Create a runnable client jar:
C:\>jar -cfe client.jar Test Test.class ServiceFac...
Create a service jar:
jar -cf service.jar HelloServiceImpl.class
Test:
C:\>java -jar client.jar
Class Loader: java.net...
Extra Note: : JDK7 added a method URLClassLoader.close() , so that a URLClassLoader can be discarded, and a new one created to load a new implementation.
Created by Dr. Xi on June 13, 2011 15:05:27
Last update: June 13, 2011 15:10:24
When you pass parameters from shell to Java, the list arguments may be messed up if there are spaces in the values.
Start with a simple Java test class:
public class EchoParams {
public static voi...
Tests:
$ java EchoParams a b c
Arg: a
Arg: b
Arg...
Now wrap the command in a shell script ( echoparams.sh ):
#!/bin/sh
java EchoParams $*
Tests:
$ ./echoparams.sh a b c
Arg: a
Arg: b
Arg...
The quotes had no effect on the parameters list.
Changing $* to $@ produces the same results.
The correct way to quote the args list is: "$@"
#!/bin/sh
java EchoParams "$@"
Test:
$ ./echoparams.sh a b "c d" "1 2 3 4 5"
Arg: a
...
Created by alfa on June 07, 2011 11:34:26
Last update: June 07, 2011 11:36:37
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...
Created by alfa on June 03, 2011 12:36:14
Last update: June 03, 2011 12:36:14
Thread local storage is typically used to associate state with a thread (e.g., a user ID or Transaction ID). This example, coming from Java API doc , assigns a unique id to each thread that calls getCurrentThreadId() . The actual usage is demonstrated with the Java concurrency package.
import java.util.concurrent.Future;
import java...
Created by alfa on June 03, 2011 12:07:52
Last update: June 03, 2011 12:07:52
import java.util.Random;
public class Rando...
Created by alfa on June 03, 2011 09:41:03
Last update: June 03, 2011 09:41:03
Dynamic proxy can be used to eliminate the need to stub out unused interface methods. This is an example for a simple SAX content handler for XML parsing.
The org.xml.sax.ContentHandler interface requires 11 methods be implemented but we only need three:
import java.io.IOException;
import java.util.Ar...
With a dynamic proxy, we don't need the empty blocks for the unused methods:
import java.io.IOException;
import java.util.Ar...
Equivalently (with anonymous inner class):
import java.io.IOException;
import java.util.Ar...
demo.xml :
<breakfast-menu>
<food>
<name>Belgian W...
Created by alfa on June 03, 2011 09:08:52
Last update: June 03, 2011 09:08:52
import java.util.Arrays;
public class Array...
Created by alfa on June 02, 2011 15:49:26
Last update: June 02, 2011 15:51:08
Facts:
Dynamic proxy classes are generated by the Java runtime, from a list of interfaces given by the user.
The generated proxy class implements all interfaces given by the user.
The dynamic proxy class is not synthetic .
The dynamic proxy class is useless without a user supplied InvocationHandler class, since there's only one constructor for the proxy class and it takes a InvocationHandler as parameter.
Example code:
import java.lang.reflect.Constructor;
import ja...
Output:
Class: $Proxy0
isSynthetic: false
Constructo...
