Java vector capacity finding the vector size

Question

I am trying to get the contents of a vector. I have a class which stores user details such as name and password:

package Login;

/**
 *
 * @author Kutoma
 */
public class User{
    private String name;
    private String password;


    public User(String aName, String password){
     name = aName;
     this.password = password;

    }


    public boolean checkPassword(String pass)
    {
        if(password.equals(pass))
            return true;
             else
            return false;

    }
    public String getName(){
        return name;
    }
    public String getPassword(){
        return password;
    }

}

I then have a class called setOfUsers which adds users and finds their names:

package Login;


public class SetOfUsers extends Vector<User> {
private static SetOfUsers register =  null;

public SetOfUsers(){
    super();
 User temp = new User("Adam","12345");
 add(temp);
}
public static SetOfUsers getInstance(){
    if (register == null)           
        { register = new SetOfUsers(); }
    return register;    
}


public void addUser(User aUser){
    super.add(aUser);
}

public User findUserByName(String name)
{
    for(int i = 0; i < capacity(); i++){

      User user = elementAt(i); 
      if(user.getName().equals(name)){
          return user;
      }

    }
    return null;
}

At the moment I am getting this error java.lang.ArrayIndexOutOfBoundsException: 1 >= 1 However, I have used capacity to find the size of the vector, not sure where I am going wrong here. My Main program has the following code when login button is clicked it should print out the user details

private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
    // TODO add your handling code here:

    SetOfUsers register = SetOfUsers.getInstance();
    String name = nameText.getText();
    User user = register.findUserByName(name);
    String passTxt = passText.getText();
    user = register.findUserByName(passTxt);
    System.out.print(user);


}                         

Answer 1

Use size() instead of capacity().

capacity():

returns the current capacity (the length of its internal data array, kept in the field elementData of this vector)

size():

returns the number of components in this vector.

Check the docs here .

Answer 2

You're using capacity() which is not the same as size() . See this SO answer for a nice introduction to the differences between the two: https://stackoverflow.com/a/2787405/1370556 .

In short, you'll want to loop through size() instead:

for(int i = 0; i < size(); i++){

As an aside, you may want to switch to ArrayLists. Make sure to read up on the differences between Vector and ArrayList in Java: Why is Java Vector class considered obsolete or deprecated? .