SCJP Sun Certified Programmer for Java 5 Study Guide (Exam 310-055) (Certification Press)
Here are the key points from this chapter.
Using javac and java (Objective 7.2)
| q | Use -d to change the destination of a class file when it's first generated by the javac command. |
| q | The -d option can build package-dependent destination classes on-the-fly if the root package directory already exists. |
| q | Use the -D option in conjunction with the java command when you want to set a system property. |
| q | System properties consist of name=value pairs that must be appended directly behind the -D, for example, Java -Dmyproperty=myvalue. |
| q | Command-line arguments are always treated as Strings. |
| q | The java command-line argument 1 is put into array element 0, argument 2 is put into element 1, and so on. |
Searching with java and javac (Objective 7.5)
| q | Both java and javac use the same algorithms to search for classes. |
| q | Searching begins in the locations that contain the classes that come standard with J2SE. |
| q | Users can define secondary search locations using classpaths. |
| q | Default classpaths can be defined by using OS environment variables. |
| q | A classpath can be declared at the command line, and it overrides the default classpath. |
| q | A single classpath can define many different search locations. |
| q | In Unix classpaths, forward slashes (/) are used to separate the directories that make up a path. In Windows, backslashes (\) are used. |
| q | In Unix, colons (:) are used to separate the paths within a classpath. In Windows, semicolons (;) are used. |
| q | In a classpath, to specify the current directory as a search location, use a dot (.) |
| q | In a classpath, once a class is found, searching stops, so the order of locations to search is important. |
Packages and Searching (Objective 7.5)
| q | When a class is put into a package, its fully qualified name must be used. |
| q | An import statement provides an alias to a class's fully qualified name. |
| q | In order for a class to be located, its fully qualified name must have a tight relationship with the directory structure in which it resides. |
| q | A classpath can contain both relative and absolute paths. |
| q | An absolute path starts with a / or a \. |
| q | Only the final directory in a given path will be searched. |
JAR Files (Objective 7.5)
| q | An entire directory tree structure can be archived in a single JAR file. |
| q | JAR files can be searched by java and javac. |
| q | When you include a JAR file in a classpath, you must include not only the directory in which the JAR file is located, but the name of the JAR file too. |
| q | For testing purposes, you can put JAR files into .../jre/lib/ext, which is somewhere inside the Java directory tree on your machine. |
Static Imports (Objective 7.1)
| q | You must start a static import statement like this: import static |
| q | You can use static imports to create shortcuts for static members (static variables, constants, and methods) of any class. |
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