Develop Reference

How to import a class that i wrote in java

So there is a folder in which there is the main.java file and a folder in which is a class,
how to import the class in main from the folder?

Direct folder import can't be achieved in java.
Following can be done
Package the other java class as jar
Include that jar in classpath of main program
Import the other java class in main program

Given your question, I'm assuming that you're a beginner. Here are the steps to follow for Eclipse IDE:
Under the class (which you want to import) go to: File -> Export -> Java -> Jar file.
Choose the resources to export and select a destination for the jar file.
In the project where you want to import the file, go to: Java Build Path -> Libraries -> Add External Jar -> Choose the jar file.
In the class where you need to use the file, write: import com.xxx.yyyy; (Package name).

Suppose we have the following:
LibA.Package1
SomeClass.class
LibA.Package2
Main.java
In your main file, you will need to use the full import path in the Main.java
import LibA.Folder1.SomeClass
See the following question for reference

Error importing package in Java

I am trying to sort my classes into packages but i can't import them.
My files are in the following folders:
- .java files are in C:\Java\Code\src\my\app\Timer
- .class files are in C:\Java\Code\compiled\my\app\Timer
In my class (timer) i've added package my.app;
Also, I have setted the CLASSPATH to look in both src and compiled folders.
Then, I have another folder where I put my "bigger" projects in:
- C:\Java\Projects\myProject
The problem is that when I try to import the class Timer into MyProject using import my.app.*; all I get is:
Error: package my.app does not exist
Culd you please give me a hand?
PS. My IDE is Dr.Java

I have found the problem.
It appears that Dr.Java ignores complitely the CLASSPATH variable. It is necessary to set in preferences where are the .class files.

How to import jar file by mac terminal

I try to import stdlib.jar in my project by terminal. The procedure is like this:
Move stdlib.jar to the folder "bin";
Add import bin.stdlib.* in the main class which residences in folder "src" and saved;
In terminal try src> javac -cp '../bin/:stdlib.jar' MyClass.java but failed to compile with the reason "package bin.stdlib does not exist". There are indeed many answers related to this issue online but I still cannot figure it out. Any advice is welcomed.

Import library is not resolved

I have tried to compile a java program, shorten.java from mp4parser site. But my jar file is unable to resolve the required import shown below.
This program needs to import library from iso mp4parser as mentioned below. In short I need jar file for shorten.java file to resolve these import.
import com.coremedia.iso.IsoFile;
import com.coremedia.iso.boxes.TimeToSampleBox;
import com.googlecode.mp4parser.authoring.Movie;
import com.googlecode.mp4parser.authoring.Track;
import com.googlecode.mp4parser.authoring.builder.DefaultMp4Builder;
import com.googlecode.mp4parser.authoring.container.mp4.MovieCreator;
import com.googlecode.mp4parser.authoring.tracks.CroppedTrack;
I have downloaded the source code from the mp4parser site to create the jar file for these library.
In below image java->com->coremedia->iso and java->com->coremedia->iso->boxes having required java program
and java->com->googlecode->mp4parser->authoring etc. having other needed java program for these import
I have created the jar by following command-
cd java // moved in java folder
jar cfv mp4parser.jar *
now add these jar to my shorten.java program.
But I am getting error that import is not resolved.
****Do anybody can tell me where I am doing mistake ???****
Here is the directory where java codes for these imports are available.

I suggest you to this:
Create a quickstart java project with maven;
Add the dependencies that you want;
Put the java class in src/main/java
mvn clean install
If it don't work, try some IDE, like eclipse. Open the project and try to fix the imports... It's always possible that some lib has changed, and maybe they change the name of the package.

Problem in packages in importing in Eclipse

I am trying to import some existing projects into Eclipse.
The structures for their packages is:
Project/
/src
/java
/a
/b
/c
Once imported in the package explorer I see:
Project
src/java
--a
--b
--c
- AClass.java
This is ok, since the classes e.g. AClass.java are defined in package: a.b.c
But in one project the structure (once imported) becomes:
Project
src
--java
--a
--b
--c
- AClass.java
And that causes the error that AClass.java is defined to be in package a.b.c but it is actually under java.a.b.c
Why is this happening? Why in this specific project java is not ignored as part of package?
Thanks

How are you creating the Eclipse projects? It sounds like you just need to put "java" as a root on on the source path here, instead of "src". You can do this by editing the build path after the import process, of course.

Remove the existing source folders first. -right click -> menu -> build path -> remove from build path
then
Right click on the source folder. build path -> use as source folder.
Seems like your settings are pointing to the parent of the source folder so src is recognized as package by eclipse.
Wrong package name when using automatically added imports in Eclipse

call the package on the top of your import statements,
like if your class is in java/main/org/goal/Main.java
then the path is package java.main.org.goal;
else do Ctrl +1 and it suggest some quick help
import the necessary package from that

Use this sentence import java.io.*; at the top of java file. Otherwise, you have to create package folder.
Import statements:
In Java if a fully qualified name, which includes the package and the class name, is given then the compiler can easily locate the source code or classes. Import statement is a way of giving the proper location for the compiler to find that particular class.
For example, the following line would ask compiler to load all the classes available in directory java_installation/java/io :
import java.io.*;