This section describes the Java launching tool 'java' and its commonly used command options.
"java": A command line tool that launches Java applications. It starts a Java virtual machine,
loads the specified class, and invokes that class's main method. "java" has the following syntax:
java [options] class [arguments]
where "options" is a list of options; "class" is the full name of a Java class to be launched;
"arguments" is a list of arguments to be passed to the main method of the class to be launched.
Another way of launching a Java class is to use the "-jar" option:
java [options] -jar file [arguments]
where "file" is a JAR file, which should contain a "Main-Class" attribute in the manifest file.
The "Main-Class" attibute defines the Java class to be launched.
Commonly used options are:
"-help" - Displays a short help text.
"-verbose" - Generates verbose output to standard output.
"-version" - Prints the version information of the launcher.
"-classpath classpath" - Specifies a list of path names where the launcher will search for compiled type definitions.
If "-classpath" is not specified, the current directory will be used as the class path.
"-Dproperty=value" - Defines a new system property, which can be accessed by the application.
If you run the "java" command without any options, you will get the quick usage information as shown below:
C:\>\j2sdk1.5.0\bin\java
Usage: java [-options] class [args...]
(to execute a class)
or java [-options] -jar jarfile [args...]
(to execute a jar file)
where options include:
-client to select the "client" VM
-server to select the "server" VM
-hotspot is a synonym for the "client" VM [deprecated]
The default VM is client.
-cp <class search path of directories and zip/jar files>
-classpath <class search path of directories and zip/jar files>
A ; separated list of directories, JAR archives,
and ZIP archives to search for class files.
-D<name>=<value>
set a system property
-verbose[:class|gc|jni]
enable verbose output
-version print product version and exit
-version:<value>
require the specified version to run
-showversion print product version and continue
-jre-restrict-search | -jre-no-restrict-search include/exclude
user private JREs in the version search
-? -help print this help message
-X print help on non-standard options
-ea[:<packagename>...|:<classname>]
-enableassertions[:<packagename>...|:<classname>]
enable assertions
-da[:<packagename>...|:<classname>]
-disableassertions[:<packagename>...|:<classname>]
disable assertions
-esa | -enablesystemassertions
enable system assertions
-dsa | -disablesystemassertions
disable system assertions
-agentlib:<libname>[=<options>]
load native agent library <libname>,
e.g. -agentlib:hprof see also,
-agentlib:jdwp=help and -agentlib:hprof=help
-agentpath:<pathname>[=<options>]
load native agent library by full pathname
-javaagent:<jarpath>[=<options>]
load Java programming language agent,
see java.lang.instrument
