如何导入包装中的jar文件？

Question

I have a jar file named stdlib-package , the .class files in this jar file are all in a edu.princeton.cs.introcs package

For example, I want to use one class named StdDraw from that jar file in my own codes

Say E:\\code is my current working directory. like other conditions, I create a subdirectory bin\\edu\\princeton\\cs\\introcs to put stdlib-package in

Here is my codes:

package com.david.test;
import edu.princeton.cs.introcs.stdlib-package.*; // any problems here ?

public class DrawTest
{
    public static void main(String[] args)
    {
        StdDraw.line(0.5, 0.5, 1, 0.5);
    }
}  

Then I put DrawTest.java in the src\\com\\david\\test

To compile the DrawTest.java , I type the commands in command line:

javac -d bin -cp bin\edu\princeton\cs\introcs\stdlib-package.jar src\com\david\test\DrawTest.java  

But it failed : package edu.princeton.cs.introcs.stdlib_package doesn't exist...

I searched for a lot of time, but haven't found the answer
Thanks for your help

EDIT===
@EJP's comment solves my question too.

Answer 1

This should be all you need in code:

import edu.princeton.cs.introcs.*

Then you only need to make sure the jar is on your class path; it doesn't matter what the name of the jar is, or where it is. If it is on your classpath, Java will load it, and use the location of the files within it.

Move the jar into a lib directory in your current directory, and do something like

javac -cp lib\stdlib-package.jar src\com\david\test\DrawTest.javac

Answer 2

Your import is wrong. There's no such package in that .jar file.

import edu.princeton.cs.introcs.*; 

In general, however, that's a bad practice and you should really only import what you need:

import edu.princeton.cs.introcs.StdDraw;

Answer 3

I understand that there is no package with 'stdlib-package' name.

If the fully qualified name of the class you are using is edu.princeton.cs.introcs.StdDraw, you can just import 'edu.princeton.cs.introcs.StdDraw'

     import edu.princeton.cs.introcs.StdDraw

If you want to load all the classes in that package

     import edu.princeton.cs.introcs.*