Question

I have download a simple java example from the net.I am trying to compile the code given below

package ArrayList;
import java.util.ArrayList;

public class SimpleArrayListExample {

    public static void main(String[] args) {

        //create an ArrayList object
        ArrayList<String> arrayList = new ArrayList<String>();

        /*
        Add elements to Arraylist using
        boolean add(Object o) method. It returns true as a general behavior
        of Collection.add method. The specified object is appended at the end
        of the ArrayList.
         */
        arrayList.add("1");
        arrayList.add("2");
        arrayList.add("3");

        /*
        Use get method of Java ArrayList class to display elements of ArrayList.
        Object get(int index) returns and element at the specified index in
        the ArrayList
         */
        System.out.println("Getting elements of ArrayList");
        System.out.println(arrayList.get(0));
        System.out.println(arrayList.get(1));
        System.out.println(arrayList.get(2));
    }
}

I have edited the program as per your suggestion and I can compile and I got the class file.

java SimpleArrayListExample.java

NOw I am trying to execute the file using

java -classpath . ArrayList.SimpleArrayListExample.java

Exception in thread “main” java.lang.NoClassDefFoundError

I google and found out that I have to specify -classpath .

http://www.tech-recipes.com/rx/826/java-exception-in-thread-main-javalangnoclassdeffounderror/ that doesn’t seem to fix the problem.

Answer 1

The compiler is warning that the type contained within the collection has not been declared.
You can use generics to emilinate this warning

ArrayList<String> arrayList = new ArrayList<String>();

Edit:

There is a problem with your package structure. The SimpleArrayListExample is not in a directory called ArrayList. To fix

• Move SimpleArrayListExample.java to a new directory called ArrayList.
• Compile using:- javac ArrayList/SimpleArrayListExample.java
• To Run: java ArrayList.SimpleArrayListExample

Note package names typically use lowercase.