In any language, debugging information is meta information. It by its nature increases the size of the object files, thus increasing load time. During execution outside a debugger, this information is actually completely ignored. As outlined (although not clearly) in the JVM spec the debug information is stored outside the bytecode stream. This means that … Read more
Let’s put it this way: I can easily produce an entirely conforming Java compiler that never produces the same .class file twice, given the same .java file. I could do this by tweaking all kinds of bytecode construction or by simply adding superfluous attributes to my method (which is allowed). Given that the specification does … Read more
Javac documentation provides all the necessary information. However, it might be useful to use Ant or Maven for command line builds. This page provides a good example of using first javac and then Ant for building a simple project. Here is an example project and how can it be compiled with javac. The tree structure … Read more
Right click on your project –> Project Properties Then in Sources set Source/Binary Format to JDK 7. EDIT 1 : There is a NetBeans issue: Works fine in J2SE project, Web project specific problem. The problem is that fork=”false” the JDK 7.0 params are passed to JDK 6.0 compiler. The executable requires fork=”true”. On the … Read more
The length of a String literal (i.e. “…”) is limited by the class file format’s CONSTANT_Utf8_info structure, which is referred by the CONSTANT_String_info structure. CONSTANT_Utf8_info { u1 tag; u2 length; u1 bytes[length]; } The limiting factor here is the length attribute, which only is 2 bytes large, i.e. has a maximum value of 65535. This … Read more
For windows: javac -cp “.;/dir/commons.jar;/dir/more_jar_files.jar” MyClass.java For unix or mac (thanks for the tip Dawood): javac -cp “.:/dir/commons.jar:/dir/more_jar_files.jar” MyClass.java Which means: javac -cp <path to jar> MyClass.java
You need to add the path to Tomcat’s /lib/servlet-api.jar file to the compile time classpath. javac -cp .;/path/to/Tomcat/lib/servlet-api.jar com/example/MyServletClass.java The classpath is where Java needs to look for imported dependencies. It will otherwise default to the current folder which is included as . in the above example. The ; is the path separator for Windows; … Read more
Try the following: javac file1.java file2.java
source: The version that your source code requires to compile. target: The oldest JRE version you want to support. Be sure to also set bootclasspath to ensure your program will work on older VMs. From the javac documentation: Cross-Compilation Example The following example uses javac to compile code that will run on a 1.6 VM. … Read more
Yes, calling getClass() has become a canonical “test for null” idiom, as getClass() is expected to be a cheap intrinsic operation and, I suppose, HotSpot might be capable of detecting this pattern and reduce the operation to an intrinsic null-check operation, if the result of getClass() is not used. Another example is creating an inner … Read more