Objectives:

Using ArrayList class from java.util package Using sort method from java Collections class Implementing Comparable interface Writing a comparator Using an iterator to iterate over the collection

Lab Assignment:

1. In this lab, you are going to store animals in the ArrayList collection from java.util package Use method add from ArrayList class to add animals to the list and use method sort from the Collections class to sort animals by the age in ascending order and by kind in ascending order (mammals first then reptiles).
2. Modify method compareTo in class Animal so it compares animals by age in ascending order.
3. Use method add from the ArrayList class to add the animals to the list.
4. To display animals you must use an iterator from the ArrayList class instead of method toString from the ArrayList. Use the iterator in AnimalGUI to step through the collection.
5. To sort animals by age use method sort(List list) from the Collections class.

Collections class from java.util package contains static methods that operate on collections. Method sort sorts the specified list into ascending order, according to the natural ordering of its elements. All elements in the list must implement the Comparable interface. Modify Animal class, so it implements interface Comparable. The implemented method compareTo should compare animals by age in ascending order.

6. To sort animals by kind use method sort(List list, Comparator c) from Collections class.

This method sorts the specified list according to the order dictated by the specified comparator object. Provide the appropriate comparator needed by Collections.sort method to sort the animals by kind. Write a class that implements interface Comparator. In this class implement method compare so it compares animals by kind (Mammals should be listed before Reptiles).

int compare(T o1, T o2)

Method compare compares its two arguments for order. Returns a negative integer, zero, or a positive integer as the first argument is less than, equal to, or greater than the second.

You can use the provided AnimalGUI class to create a list of animals and to test the sort methods. You can also create your own test class.

AnimalSortFrameStart//

package gui;

import java.awt.*; import java.awt.event.*; import javax.swing.*;

public class AnimalSortFrameStart extends JFrame implements ActionListener {

/** * GUI component for getting the name */ private GetInputPanel namePanel = null; /** * GUI component for getting the weight */ private GetInputPanel weightPanel = null; /** * GUI component for getting the age */ private GetComboPanel agePanel = null; /** * GUI component for getting the length */ private GetComboPanel lengthPanel = null; /** * GUI component for getting the color */ private GetInputPanel colorPanel = null;

/** * Button for adding a reptile to the collection */ private final JButton addReptileButton = new JButton("Add Reptile"); /** * Button for adding a mammal to the collection */ private final JButton addMammalButton = new JButton("Add Mammal"); /** * Button for displaying animals in the collection */ private final JButton displayAnimalsButton = new JButton("Display Animals"); /** * Button for sorting animals in the collection by name */ private final JButton sortAgeButton = new JButton("Sort Animals by Age"); /** * Button for sorting animals in the collection by kind */ private final JButton sortKindButton = new JButton("Sort Animals by kind"); /** * A for displaying data */ private final JTextArea verifyArea = new JTextArea(25, 45);

/** * Creates a new instance of AddAnimalFrame which is contains panels and other * GUI components */ public AnimalSortFrameStart() { super("Add and Sort Animals by name and by kind"); createGUI(); }

/** * A method to create GUI components */ private void createGUI() { Container c = this.getContentPane(); c.setLayout(new BorderLayout(5, 5));

JPanel inputPanel = new JPanel(); //contains GUI to input animals info inputPanel.setLayout(new GridLayout(5, 1)); namePanel = new GetInputPanel(20, " Animal's Name: "); inputPanel.add(namePanel); weightPanel = new GetInputPanel(6, " Animal's Weight (lb): "); inputPanel.add(weightPanel); agePanel = new GetComboPanel(" Animal's Age (years):", 125); inputPanel.add(agePanel); lengthPanel = new GetComboPanel("Reptile's Length (cm)", 1000); inputPanel.add(lengthPanel); colorPanel = new GetInputPanel(20, "Mammal's skin/fur color"); inputPanel.add(colorPanel);

JPanel buttonPanel = new JPanel(); //contains buttons buttonPanel.setLayout(new GridLayout(1, 5, 5, 5)); addReptileButton.setToolTipText("Press to add Reptile"); addMammalButton.setToolTipText("Press to add Mammal"); buttonPanel.add(addReptileButton); buttonPanel.add(addMammalButton);

buttonPanel.add(displayAnimalsButton); buttonPanel.add(sortAgeButton); buttonPanel.add(sortKindButton);

c.add(inputPanel, BorderLayout.NORTH); c.add(buttonPanel, BorderLayout.CENTER); JScrollPane scrollPane = new JScrollPane(verifyArea); c.add(scrollPane, BorderLayout.SOUTH);

addReptileButton.addActionListener(this); addMammalButton.addActionListener(this); displayAnimalsButton.addActionListener(this);

sortAgeButton.addActionListener(this); sortKindButton.addActionListener(this); setVisible(true); }

/** * main() instantiates an object * * @param argv */ static public void main(String[] argv) { AnimalSortFrameStart animalFrame = new AnimalSortFrameStart(); animalFrame.setSize(800, 650); animalFrame.setDefaultCloseOperation(EXIT_ON_CLOSE); }

/** * Responds to the "Display" and "Add" buttons * * @param ev The button press event */ public void actionPerformed(ActionEvent ev) { Object object = ev.getSource(); if (object == addReptileButton) {

} else if (object == addMammalButton) {

} else if (object == sortKindButton) {

} else if (object == sortAgeButton) {

} else {

} }

/** * A panel prompting for String input. It contains a label and a text field. */ class GetInputPanel extends JPanel {

private JTextField inputField; //used for the user input

/** * Constructor sets up a label and the text field * * @param size the size of the input text field * @param prompt the message specifying expected input */ public GetInputPanel(int size, String prompt) { inputField = new JTextField(size); JLabel label = new JLabel(prompt); add(label); add(inputField); }

/** * Gets the text from the text field * * @return Returns the text from the text field */ public String getText() { return inputField.getText(); }

/** * Converts the text field value into a number and displays an error message * when inputed data contains non digit characters * * @return the integer represented by the user input */ public double getValue() { double value = 0.0; try { value = Double.parseDouble(inputField.getText()); } catch (NumberFormatException ex) { JOptionPane.showMessageDialog(null, "Invalid characters in number", "Input Error", JOptionPane.ERROR_MESSAGE); } return value; } }

/** * This panel represents a panel with a label and a combo box. */ class GetComboPanel extends JPanel {

JLabel label; //explains the purpose of the combo box JComboBox ageCombo; //used for the user input

/** * Constructor sets up a panel with a label and a combo box. * * @param message the text indicating the purpose of the combo box * @param numChoices the range of choices displayed in the combo box */ public GetComboPanel(String message, int numChoices) { label = new JLabel(message); String[] age = new String[numChoices];

for (int i = 0; i < age.length; i++) { age[i] = i + 1 + ""; } ageCombo = new JComboBox(age);

add(label); add(ageCombo); }

/** * Gets the value from the combo box * * @return value selected from the combo box */ public int getValue() { int a; a = Integer.parseInt((String) ageCombo.getSelectedItem()); return a; } } }