[FIXED] How to create a "java.lang.Class" object from a .java file in java

Issue

How can I instantiate an object of the class java.lang.Class from a given .java file?

I want to create an application to automatically generate JUnit tests. For that I would need "Method" objects and for "Method" objects I need to have a "Class" object.

Solution

java 6 onwards has an api for the compiler: http://www.javabeat.net/2007/04/the-java-6-0-compiler-api/

the link above includes an example.

here's another example - http://www.java2s.com/Code/Java/JDK-6/JavaCompilertoolshowyoucancompileaJavasourcefrominsideaJavaprogram.htm

to load the file once compiled you use a classloader. there's an example at http://tutorials.jenkov.com/java-reflection/dynamic-class-loading-reloading.html and another at http://www.javaworld.com/jw-10-1996/jw-10-indepth.html

you'd think there would be a library to simplify all this. i can't find one, but am still looking.

meanwhile, here's a really nice article from ibm that compiles a function and plots it - http://www.ibm.com/developerworks/java/library/j-jcomp/index.html

found one http://docs.codehaus.org/display/JANINO/Home - this is a library that simplifies the process. i would recommend configuring it to use the javax.tools API (see last sentence in the "what is Janino" paragraph).

sorry for the google snark earlier.

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it just struck me that maybe you just want a class object.

if you have a class called MyClass then the associated class is Myclass.class. that's probably obvious, but perhaps that's all you need.

and if you have the class name in a string you can use this method - http://docs.oracle.com/javase/1.4.2/docs/api/java/lang/Class.html#forName(java.lang.String)

Answered By - andrew cooke
Answer Checked By - Dawn Plyler (JavaFixing Volunteer)