Java list class methods from command line

Question

Is it possible to get a list of methods of the class from command line?

In Eclipse or Intellij IDEA one usually hits ctrl + space for autocompletion menu. It's cool, but I wish to get something alike from bash.

E.g. I have a class that extends a class (or classes if the parent also extends a class) and implements a couple of interfaces - so I need to know which methods I'm able to use.

P.S. I use vim 'cause I have memory limitations to use entire IDE.

For c you could use cscope, I don't think there is such a tool for Java. You could probably write one. There is the, sadly not up to date, Java Development Environment for Emacs. — Elliott Frisch
– Elliott Frisch, Commented Aug 22, 2016 at 2:34
This wouldn't be very hard to implement yourself. You could write a Java program that uses Class.forName(args[0]).getMethods() and display them. — castletheperson
– castletheperson, Commented Aug 22, 2016 at 2:44

Community · Accepted Answer · 2020-06-20 09:12:55Z

3

You can use the java disassembler: javap:

Example

Compile the following DocFooter class:

import java.awt.*;
import java.applet.*;
 
public class DocFooter extends Applet {
        String date;
        String email;
 
        public void init() {
                resize(500,100);
                date = getParameter("LAST_UPDATED");
                email = getParameter("EMAIL");
        }
 
        public void paint(Graphics g) {
                g.drawString(date + " by ",100, 15);
                g.drawString(email,290,15);
        }
}

The output from the javap DocFooter.class command yields the following:

Compiled from "DocFooter.java"
public class DocFooter extends java.applet.Applet {
  java.lang.String date;
  java.lang.String email;
  public DocFooter();
  public void init();
  public void paint(java.awt.Graphics);
}

edited Jun 20, 2020 at 9:12

CommunityBot

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answered Aug 22, 2016 at 2:50

Andreas

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6 Comments

Umbra Aeternitatis Over a year ago

Hmm, I didn't know about javap disassembler and it's features. Thank for the hint. It does work like a charm on custom classes, but I also wished to disassemble standard Java classes (like e.g. ArrayList) to get fast-list of fields/constructors/methods (if it is possible).

Andreas Over a year ago

The standard Java classes are all inside rt.jar and a jar file is just a zip file, so you can extract whichever class file you want and decompile it.

Umbra Aeternitatis Over a year ago

Severe decision, but it works. As far as I understood, javap can't read a class from stdin, can it?

Erwin Bolwidt Over a year ago

@UmbraAeternitatis Just type javap -private java.util.ArrayList on the command line (or don't use -private if you don't want private methods/fields)

Umbra Aeternitatis Over a year ago

I tried to javap ArrayList, but... I failed to understand to pass full path.

|

Erik Pragt · Accepted Answer · 2016-08-22 02:41:21Z

0

While I would advice spending a bit of money on more RAM, you could using ctags instead. I'm not sure if it's up to date with Java 7/8/9 features, but here's a blog describing how to use it: http://andrewradev.com/2011/06/08/vim-and-ctags/

answered Aug 22, 2016 at 2:41

Erik Pragt

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1 Comment

Umbra Aeternitatis Over a year ago

ctags seems to be interesting tool. Perhaps I should try it - I can't get any effect from it for now. It's does not seem to be trivial.

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