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1. Compile java source code with classpath
2. Javadoc command line Javadoc exmaple
3. Java generate directory from package name and without package name.

1 Compile java source code with classpath

If you are Java developer, you will waste a lots of hell time on classpath hell.
- Class files are not found.
- A package is not found.
- jar files are not found.
Assume you have a java file called /user/myfile.java and myfile.java uses some packages in /lib/mylib.jar
you need to compile the myfile.java as following:

-d specified where to store class files.

javac -classpath /lib/*:.  -d /tmp/classfile /user/myfile.java

jar file is in /lib and class file myfile.class will be in /tmp/classfile

The following will work with double quotes

javac -classpath "/lib/*" -d /tmp/classfile /user/myfile.java

Following will NOT work under shell script or shell command
- The difference between /lib/* and "/lib/*"
```
javac -claspath /lib/* -d /tmp/classfile /usr/myfile.java
```
Show all the classpath at runtime, it is very useful.
- Check whether you include all the jar files.
```
String path = System.getProperty("java.class.path");
System.out.println(path);
```

-classpath $ \Rightarrow $ /lib/* $ \Rightarrow $ expand to

/lib/*
=> /lib/myjar.jar:/lib/mylib.jar  # MacOS or Linux
=> /lib/myjar.jar;/lib/mylib.jar   # Windows

If your java file use jar and class file as a library, your class file called *MyClass.class" in /user/MyClass/MyClass.class Here is the javac compiler command line
- The following command will search jar file under /lib" and search *class file* under ~/user/MyClass
```
# It works.
javac -classpath "/lib/*:/user/MyClass" -d /tmp/classfile /user/myfile.java
# It will not work.
javac -classpath "/lib/*:/user/MyClass/*.class" -d /tmp/classfile /user/myfile.java
```

2 Javadoc command line Javadoc exmaple

# it works
javadoc -classpath "/myjar/*:/user/MyClass" -d /htmlfile -sourcepath $b/javalib  *.java
# it works
javadoc -classpath $b/javalib/jar/*:.  -noqualifier all -d /Library/WebServer/Documents/zsurface/htmljavadoc -sourcepath $b/javalib *.java

The following will NOT work, the difference is: $b/javalib/*.java $ \Rightarrow $ $b/javalib *.java

javadoc -classpath "/myjar/*:/user/MyClass" -d /htmlfile -sourcepath $b/javalib/*.java

3 Java generate directory from package name and without package name.

Assume Hello.java is in /myfile/Hello.java
If package com.xfido inside the Hello.java file
It will generate a directory com/xfido under current directory and Hello.class file is in com/xfido
```
package com.xfido
javac -d . Hello.java
```
Change root directory to /tmp of package name

com/xfido will be generated under /tmp

package com.xfido
javac -d /tmp Hello.java

It will NOT generate any dir and Hello.class will be in the current dir.
```
javac Hello.java
```

Table of Contents

1 Compile java source code with classpath

2 Javadoc command line Javadoc exmaple

3 Java generate directory from package name and without package name.