i have 2 files User.java and ArrayListDemo.java
i complie the two file(javac *.java)

then, i type java ArrayListDemo
there is an error
please tell me why

C:\jakarta-tomcat-4.1.12\webapps\ch8\WEB-INF\classes\com\wrox\utilities>java Arr
ayListDemo
Exception in thread "main" java.lang.NoClassDefFoundError: ArrayListDemo (wrong
name: com/wrox/utilities/ArrayListDemo)
        at java.lang.ClassLoader.defineClass0(Native Method)
        at java.lang.ClassLoader.defineClass(ClassLoader.java :509)
        at java.security.SecureClassLoader.defineClass(Secure ClassLoader.java:12
3)
        at java.net.URLClassLoader.defineClass(URLClassLoader .java:246)
        at java.net.URLClassLoader.access$100(URLClassLoader. java:54)
        at java.net.URLClassLoader$1.run(URLClassLoader.java: 193)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.j ava:186)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:3 06)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launche r.java:265)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:2 62)
        at java.lang.ClassLoader.loadClassInternal(ClassLoade r.java:322)

***********************here is my code***************************
User.java
package com.wrox.utilities;

public class User {

    String username;
    String phonenumber;

    public User() {}

    public User(String uname, String pnum) {
        username = uname;
        phonenumber = pnum;
    }

    void setUsername(String uname) {
        this.username = uname;
    }

    String getUsername() {
        return username;
    }

    void setPhonenumber(String pnum) {
        this.phonenumber = pnum;
    }

    String getPhonenumber() {
        return phonenumber;
    }
}

ArrayListDemo.java
package com.wrox.utilities;
import java.util.ArrayList;

public class ArrayListDemo {
    public static void main(String[] args) {
        User usr1 = new User("Joanne Yu", "0968000669");
        User usr2 = new User("Elaine Tsai", "0968469933");
        User usr3 = new User("Ogg", "0925");

        ArrayList userlist = new ArrayList();
        userlist.add(usr3);
        userlist.add(usr2);
        userlist.add(usr1);

        User usr = (User) userlist.get(1);
        System.out.println(usr.getUsername());
        System.out.println(usr.getPhonenumber());

        for(int i=0;i<userlist.size();i++) {
            usr = (User) userlist.get(i);
            System.out.println(usr.getUsername());
            System.out.println(usr.getPhonenumber());
        }
    }

}

This exception often occur when you souldon't define your package in your classpath. So check you class path. and then tell me if it work.


Mohammad Asif Khan
Niit Distributive Computing Research group
Nust Institute of Information Technology
Email: [email protected]

it can be work when i type
java com.wrox.utilities.ArrayListDemo
but
java ArrayListDemo
still has error

i checked my classpath many times
.;C:\j2sdk1.4.0_02\lib;C:\j2sdk1.4.0_02\lib\tools. jar;C:\jakarta-tomcat-4.1.12\common\lib;C:\jakarta-tomcat-4.1.12\common\lib\servlet.jar;

add the user.class in the current classpath and then run....gennerally it looks for user.java and since it doesnt find that class it raises exception..........

Try this way...may be it should work