I got this code to instantiate a Life class from jar file:
import com.life.Life;
import java.io.File;
import java.net.URL;
import java.net.URLClassLoader;
public class Main {
public static void main(String[] args) {
try{
File file = new File("Life.jar");
URL url = file.toURI().toURL();
URL[] urls = new URL[]{url};
ClassLoader cl = new URLClassLoader(urls);
Class cls = cl.loadClass("com.life.Life");
Life life = (Life) cls.newInstance();
System.out.println("Message: "+life.getMessage());
}catch(Exception e){
e.printStackTrace();
}
}
}
Here's the content of the Life.jar
public class Life {
public String getMessage(){
return "Life is Beautiful!";
}
}
Here's my interface name Life
package com.life;
public interface Life {
public String getMessage();
}
The code above will throw an error:
java.lang.InstantiationException: com.life.Life
at java.lang.Class.newInstance0(Class.java:340)
at java.lang.Class.newInstance(Class.java:308)
at com.Main.main(Main.java:20)
BUILD SUCCESSFUL (total time: 0 seconds)
What's wrong with the code? How to resolve this?
This happened because your interface is also named Life ( java tried to instantiate an interface). Change public interface Life
to public interface LifeInterface
and then have your class Life implement that like :
public class Life implements LifeInterface
{
@Override
public String getMessage()
{
return "Life is Beautiful!";
}
}
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