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Start your free trialKarthik Ram
1,534 PointsGetting an error that arguments passed in from the main method in Main.java is null. Why ?
When I pass args[0] and args[1] in "Forum forum = new Forum (args[0] , args[1]);", it shows an error that the args[0], args[1] are still null occupied. Can anyone help me out
public class Forum {
private String topic;
public Forum( String topic){
this.topic = topic;
}
// TODO: add a constructor that accepts a topic and sets the private field topic
public String getTopic() {
return topic;
}
public void addPost(ForumPost post) {
System.out.printf("A new post in %s topic from %s %s about %s is available",
topic,
post.getAuthor().getFirstName(),
post.getAuthor().getLastName(),
post.getTitle()
);
}
}
public class User {
private String firstName,lastName;
// TODO: add private fields for firstName and lastName
public String getFirstName(){
return firstName;
}
public String getLastName(){
return lastName;
}
public User(String firstName, String lastName) {
firstName = getFirstName();
lastName = getLastName();
// TODO: set and add the private fields
}
// TODO: add getters for firstName and lastName
}
public class ForumPost {
private User author;
private String title;
private String description;
// TODO: add a constructor that accepts the author, title and description
public ForumPost( User author, String title, String description){
this.author = author;
this.title = title;
this.description = description;
}
public User getAuthor() {
return author;
}
public String getTitle() {
return title;
}
public String getDescription() {
return description;
}
}
public class Main {
public static void main(String[] args) {
System.out.println("Beginning forum example");
if (args.length < 2) {
System.out.println("Usage: java Main <first name> <last name>");
System.err.println("<first name> and <last name> are required");
System.exit(1);
}
Forum forum = new Forum("Java");
// TODO: pass in the first name and last name that are in the args parameter
User author = new User( args[0], args[1]);
// TODO: initialize the forum post with the user created above and a title and description of your choice
ForumPost post = new ForumPost( author,"Time Waste","Is Injurious");
forum.addPost(post);
// */
}
}
1 Answer
Umesh Ravji
42,386 PointsHi Karthik, the problem is with the User
class constructor. The values of firstName
and lastName
need to be set here to what is passed in. If you follow what your code is actually doing, you should be able to see why they are both set to NULL
when you create a User
object.
public User(String firstName, String lastName) {
this.firstName = firstName;
this.lastName = lastName;
}