Activity 5.3 - Completing the coding of the LinkingInfo class

Topic

This activity uses the ArrayList class.

Materials

In addition to the Solution document, the project for this activity contains three classes:

• ComputerErrorException, a user-defined exception class already written;
• LinkingInfo, which has two incomplete methods;
• LinkingInfoTest which contains test code.

Task

An instance of LinkingInfo contains the name of a computer on a local network, together with the names of all the computers to which it is linked. The names of the linked computers are held in an ArrayList instance.

The class has the following methods:

• String getComputerName()

  returns the name of the computer.

• int getNumberOfLinks()

  returns the number of computers that are linked to the first computer.

• boolean isLinked(String comp1)

  returns true if the computer comp1 is linked to the computer documented by this object, otherwise it returns false.

• void addComputer(String comp1)

  adds the name of computer comp1 to the list of linked computers. If the name is already in the list a ComputerErrorException exception is thrown with the message "Computer XXX already in links".

• void removeComputer(String comp1)

  removes the computer named comp1 from the list of linked computers. If the name is not in the list a ComputerErrorException exception is thrown with the message "Computer XXX not in links".

• void listLinkedComputers()

  prints a list of the linked computers.

The methods for adding and removing names are incomplete. Your job is to write these methods as specified above.

Instructions

Open LinkingInfo and complete the methods addComputer and removeComputer in the places indicated.

Run the project, and check that the output is as you expected