bytecode

Are there currently (Java 6) things you can do in Java bytecode that you can't do from within the Java language? I know both are Turing complete, so read "can do" as "can do significantly faster/better, or just in a different way". I'm thinking of extra bytecodes like invokedynamic , which can't be generated using Java, except that specific one is for a future version. Joachim Sauer As far as I know there are no major features in the bytecodes supported by Java 6 that are not also accessible from Java source code. The main reason for this is obviously that the Java bytecode was designed with

I have some method, which contains instrustion like ILOAD, and I want in some way to get value of stack after this instruction. Not just type, but exact value. I know I need to emulate method execution in order to do that, but I don't know how to make this properly. I have such method for test called main : sipush 15649 istore_0 /* c */ getstatic java/lang/System.out:Ljava/io/PrintStream; bipush 45 bipush 11 iload_0 /* c */ ... I want to get value, loaded by iload_0 . I tried to make Analyzer and then see Frame values, but they only contains type of values, not exact what I want. ClassReader

how to take the methods of other classes invoked in a specific method? EXAMPLE method getItem1() public String getItem1() throws UnsupportedEncodingException{ String a = "2"; a.getBytes(); a.getBytes("we"); System.out.println(a); int t = Integer.parseInt(a); return a; } The methods called in getItem1() are: String.getBytes() String.getBytes(String) PrintStream.println(String) Integer.parseInt(String) I would do this with javassist . So let's say you have the following class accessible in your classpath and want to find all methods invoked from getItem1() : class MyClass { public String

In Java, is there a way (at runtime) to obtain the bytecode which defined a particular class? Put another way, is there a way to obtain the byte[] array passed to ClassLoader.defineClass(String name, byte[] b, int off, int len) when a particular class was loaded? I see that this method is declared final , so creating a custom ClassLoader to intercept class definitions seems out of the question. In the past, I have used the class's ClassLoader to obtain the bytecode via the getResourceAsStream(String) method, but I would prefer a more canonical solution. stacker Here is a description how to