Thread: how to include and access a data file in a jar

I would like to add some data files to my class jar and access them.

package urltest;
 
import java.net.URL;
public class UrlTest {
public String getImage(String dirName) {
        URL folder = UrlTest.class.getResource( dirName );
        if( folder != null ) {
            return ( folder.getPath() );
        }
        System.out.println(dirName + "  not found!!!");
        return null; //example.txt TODO: Better error handling
    }
 
    public static void main(String[] args) {
    String dirName=".";
    String dirPath;
 UrlTest myFolder = new UrlTest(); 
 dirPath=myFolder.getImage(dirName);
    System.out.println("Directory path=" + dirPath);
 
}
}

when I build and excute this progam I get
java -jar UrlTest.jar
. not found!!!
Directory path=null

If update the jar file with the files I am unable to find them .
Greatly appreciate help
Peter

One way to read files from a jar file with code from within the jar file is to use one of the Class class's getResouce methods.

Originally Posted by Norm

One way to read files from a jar file with code from within the jar file is to use one of the Class class's getResouce methods.

Hi Norm
I do not understand your answer.
I added getPathName to the class ran it in netbeans then
ran clean and build and executed the jar file.
The results show that get resources mehtod returns null
but the straight pathname points to the same directory as the jar file
Really would like to find the answer. Thanks
************************************************** ****

package urltest;
 
import java.io.File;
import java.net.URL;
public class UrlTest {
public String getUrl(String dirName) {
        URL folder = UrlTest.class.getResource( dirName );
        if( folder != null ) {
            return ( folder.getPath() );
        }
        System.out.println(dirName + "  URL  not found!!!");
        return null; //example.txt TODO: Better error handling
}
 public String getPathName( String pathName)  {
     File file = new File(pathName); 
     if (file != null){
         return (file.getAbsolutePath());
     }
         System.out.println("getPathName Not Found "+ pathName);
         return (null);
     }
 
 
    public static void main(String[] args) {
    //String dirName="example.txt";
        String dirName=".";
    String dirPath;
 UrlTest myFolder = new UrlTest(); 
 dirPath=myFolder.getUrl(dirName);
    System.out.println("URL path=" + dirPath);
 dirPath = myFolder.getPathName(dirName);
        System.out.println("Directory Path= " + dirPath);
}
}

run:
URL path=/home/pdk/NetBeansProjects/UrlTest/build/classes/urltest/
Directory Path= /home/pdk/NetBeansProjects/UrlTest/.
BUILD SUCCESSFUL (total time: 0 seconds)

Performed Clean and Build.

pdk@pdk64:~/NetBeansProjects/UrlTest/dist$ java -jar UrlTest.jar
. URL not found!!!
URL path=null
Directory Path= /home/pdk/NetBeansProjects/UrlTest/dist/.
************************************************** ******************
code/


--- Update ---

Originally Posted by Norm

One way to read files from a jar file with code from within the jar file is to use one of the Class class's getResouce methods.

Hi Norm
I do not understand your answer.
I added getPathName to the class ran it in netbeans then
ran clean and build and executed the jar file.
The results show that get resources mehtod returns null
but the straight pathname points to the same directory as the jar file
Really would like to find the answer. Thanks
************************************************** ****

code/
package urltest;

import java.io.File;
import java.net.URL;
public class UrlTest {
public String getUrl(String dirName) {
URL folder = UrlTest.class.getResource( dirName );
if( folder != null ) {
return ( folder.getPath() );
}
System.out.println(dirName + " URL not found!!!");
return null; //example.txt TODO: Better error handling
}
public String getPathName( String pathName) {
File file = new File(pathName);
if (file != null){
return (file.getAbsolutePath());
}
System.out.println("getPathName Not Found "+ pathName);
return (null);
}


public static void main(String[] args) {
//String dirName="example.txt";
String dirName=".";
String dirPath;
UrlTest myFolder = new UrlTest();
dirPath=myFolder.getUrl(dirName);
System.out.println("URL path=" + dirPath);
dirPath = myFolder.getPathName(dirName);
System.out.println("Directory Path= " + dirPath);
}
}

run:
URL path=/home/pdk/NetBeansProjects/UrlTest/build/classes/urltest/
Directory Path= /home/pdk/NetBeansProjects/UrlTest/.
BUILD SUCCESSFUL (total time: 0 seconds)

Performed Clean and Build.

pdk@pdk64:~/NetBeansProjects/UrlTest/dist$ java -jar UrlTest.jar
. URL not found!!!
URL path=null
Directory Path= /home/pdk/NetBeansProjects/UrlTest/dist/.
************************************************** ******************
code/

--- Update ---

Jst read the second thread you sent me , I'll stick with keeping the data files outside the jar.
Thanks again. Peter

get resources mehtod returns null

That would mean that the path it was given was wrong.
Here is the output I get when I execute the code from a class file not in a package and not in a jar:

URL path=/D:/JavaDevelopment/Testing/ForumQuestions12/UrlTest.java
Directory Path= D:\JavaDevelopment\Testing\ForumQuestions12\UrlTes t.java

From inside of a jar file:

D:\JavaDevelopment\Testing\ForumQuestions12\Testin g\TestPackages>java -jar _Test2.jar
URL path=file:/D:/JavaDevelopment/Testing/ForumQuestions12/Testing/TestPackages/_Test2.jar!/Test2/UrlTest.java
Directory Path= D:\JavaDevelopment\Testing\ForumQuestions12\Testin g\TestPackages\UrlTest.java

D:\JavaDevelopment\Testing\ForumQuestions12\Testin g\TestPackages>MORE

Try fixing the path and filename


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