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Day-to-Day Java Development Tools and Techniques
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Day-to-Day Java Development Tools and Techniques
There are some common things that are useful to know in many day-to-day Java development activities. It is especially helpful for someone new to Java development to know where to find this information, but I have found bookmarking these sources to be useful even as I have gained experience developing Java applications. Because one of the primary purposes for me writing a blog is to provide myself with an easy way to find things I am looking for, I am using this blog posting to collect some of these sources of information that I frequently use for Java development in one place. Because these items are related to the development of Java applications rather than to source code, it is not surprising that many of the items are specific to the JVM I am using.
Java Processes: jps
There are many times in Java development when it is important to know which Java processes are running. More specifically, I find myself needing the process ID of Java applications for running other tools against those processes or for terminating processes. There are several Sun JDK development tools, but one of my favorites is the jps tool (JVM Process Status Tool). This "experimental" tool lists the Java processes running on the target HotSpot JVM. As I previously blogged, my favorite use of this tool is jps -lm.
JVM Arguments
Java Application Launcher
The environment a Java application runs in can be significantly tweaked via the use of JVM arguments. In addition, JVM arguments allow for different levels of monitoring and analysis of the executing Java application. The command java -help lists the standard options (standard across different JVM implementations) for the Java application launcher. The command java -X can be used to see the Java application launcher`s non-standard (X for extension specific to that JVM) arguments. In the HotSpot JVM, some frequently used extension arguments are -Xms and -Xmx for initial Java heap size and maximum Java heap size respectively.
The -Xbootclasspath option can be used to either prepend (/p) or append (/a) resources to the bootstrap classpath.
If you wish to detect which JVM arguments your currently running Java application is using, you can use the ManagementFactory.getRuntimeMXBean().getInputArguments() call as described in Accessing JVM Arguments from Java. This technique takes advantage of Platform MXBeans available since J2SE 5 (custom MXBeans support was added in Java SE 6).
Two useful sources of information on the JVM parameters available when using Sun`s JVM are A Collection of JVM Options and Charles Nutter`s Favorite Hotspot JVM Flags. Both of these resources list and describe some/all of the not-recommended-for-the-casual-developer double X arguments (-XX) that are available.
Java Compiler
The javac Java compiler also has command-line arguments that can be of great use. Like the java application launcher, the javac compiler that comes with the Sun Java SDK includes both standard options and non-standard/extension options. These options are displayed in a manner consistent with that used for the application launcher. Non-standard options include bootstrap classpath append and prepend options, setting of endorsed standards path, setting of directory of installed extensions, and enabling and disabling of specific warnings (-Xlint options including -Xlint:path).
Warnings
-Xlint
The warnings reported by the Java compiler can be very useful in identifying things that either may be larger current problems than one realizes or could easily turn into more significant problems. Sun`s javac compiler allows one to take relatively granular control of which warnings are enabled and disabled using -Xlint (all warnings are reported when this is used by itself). Specific warnings can be reported by providing the type of warning after the -Xlint: notation. If no reports of warnings are desired (other than those the Java Language Specification requires), the notation -Xlint:none is used.
@SuppressWarnings
One can use the @SuppressWarnings annotation introduced with J2SE 5 to mark in code the warnings that should not be reported when the code is compiled. However, a natural question is which specific warnings can be suppressed in-code using this annotation. It turns out that this is compiler-specific. For Sun`s compiler, the available warnings that can be suppressed with @SuppressWarnings are listed here and here.
Source:
http://www.javaworld.com/community/?q=node/2462
Java Processes: jps
There are many times in Java development when it is important to know which Java processes are running. More specifically, I find myself needing the process ID of Java applications for running other tools against those processes or for terminating processes. There are several Sun JDK development tools, but one of my favorites is the jps tool (JVM Process Status Tool). This "experimental" tool lists the Java processes running on the target HotSpot JVM. As I previously blogged, my favorite use of this tool is jps -lm.
JVM Arguments
Java Application Launcher
The environment a Java application runs in can be significantly tweaked via the use of JVM arguments. In addition, JVM arguments allow for different levels of monitoring and analysis of the executing Java application. The command java -help lists the standard options (standard across different JVM implementations) for the Java application launcher. The command java -X can be used to see the Java application launcher`s non-standard (X for extension specific to that JVM) arguments. In the HotSpot JVM, some frequently used extension arguments are -Xms and -Xmx for initial Java heap size and maximum Java heap size respectively.
The -Xbootclasspath option can be used to either prepend (/p) or append (/a) resources to the bootstrap classpath.
If you wish to detect which JVM arguments your currently running Java application is using, you can use the ManagementFactory.getRuntimeMXBean().getInputArguments() call as described in Accessing JVM Arguments from Java. This technique takes advantage of Platform MXBeans available since J2SE 5 (custom MXBeans support was added in Java SE 6).
Two useful sources of information on the JVM parameters available when using Sun`s JVM are A Collection of JVM Options and Charles Nutter`s Favorite Hotspot JVM Flags. Both of these resources list and describe some/all of the not-recommended-for-the-casual-developer double X arguments (-XX) that are available.
Java Compiler
The javac Java compiler also has command-line arguments that can be of great use. Like the java application launcher, the javac compiler that comes with the Sun Java SDK includes both standard options and non-standard/extension options. These options are displayed in a manner consistent with that used for the application launcher. Non-standard options include bootstrap classpath append and prepend options, setting of endorsed standards path, setting of directory of installed extensions, and enabling and disabling of specific warnings (-Xlint options including -Xlint:path).
Warnings
-Xlint
The warnings reported by the Java compiler can be very useful in identifying things that either may be larger current problems than one realizes or could easily turn into more significant problems. Sun`s javac compiler allows one to take relatively granular control of which warnings are enabled and disabled using -Xlint (all warnings are reported when this is used by itself). Specific warnings can be reported by providing the type of warning after the -Xlint: notation. If no reports of warnings are desired (other than those the Java Language Specification requires), the notation -Xlint:none is used.
@SuppressWarnings
One can use the @SuppressWarnings annotation introduced with J2SE 5 to mark in code the warnings that should not be reported when the code is compiled. However, a natural question is which specific warnings can be suppressed in-code using this annotation. It turns out that this is compiler-specific. For Sun`s compiler, the available warnings that can be suppressed with @SuppressWarnings are listed here and here.
Source:
http://www.javaworld.com/community/?q=node/2462
