javap - Java class file disassembler

SYNOPSIS

DESCRIPTION

    class C {
        static int a = 1;
        static {
	    System.out.println(a);
        }
        static {
	    a++;
	    b = 7;
	    System.out.println(a);
	    System.out.println(b);
        }
        static int b = 2;
        static {
	    System.out.println(b);
        }
        public static void main(String args[]) {
	    C c = new C();
        }
    }

When the resulting class C is passed to javap using no options the following output results:

    Compiled from /home/weisblat/C.java
    private class C extends java/lang/Object {
        static int a;
        static int b;
        public static void main(java/lang/String []);
        public C();
        static void ();
    }

OPTIONS

-p

Prints out the private and protected methods and fields of the class in addition to the public ones.

-c

Prints out disassembled code, i.e., the instructions that comprise the JAVA bytecodes, for each of the methods in the class. For example, passing class C to javap using the -c flag results in the following output:

    Compiled from /home/weisblat/C.java
    private class C extends java/lang/Object {
        static int a;
        static int b;
        public static void main(java/lang/String []);
        public C();
        static void ();

    Method void main(java/lang/String [])
       0 new #4 
       3 invokenonvirtual #9 ()V>
       6 return

    Method C()
       0 aload_0 0
       1 invokenonvirtual #10 ()V>
       4 return

    Method void ()
       0 iconst_1
       1 putstatic #7 
       4 getstatic #6 
       7 getstatic #7 
      10 invokevirtual #8 
      13 getstatic #7 
      16 iconst_1
      17 iadd
      18 putstatic #7 
      21 bipush 7
      23 putstatic #5 
      26 getstatic #6 
      29 getstatic #7 
      32 invokevirtual #8 
      35 getstatic #6 
      38 getstatic #5 
      41 invokevirtual #8 
      44 iconst_2
      45 putstatic #5 
      48 getstatic #6 
      51 getstatic #5 
      54 invokevirtual #8 
      57 return

    }

-classpath path

Specifies the path javap uses to look up classes. Overrides the default or the CLASSPATH environment variable if it is set. Directories are separated by colons. Thus the general format for path is:

    .:<your_path>

For example:

    .:/home/avh/classes:/usr/local/java/classes

ENVIRONMENT VARIABLES

CLASSPATH

Used to provide the system a path to user-defined classes. Directories are separated by colons, for example,

    .:/home/avh/classes:/usr/local/java/classes

SEE ALSO