我真的需要一些这方面的帮助。 我不确定如何完成第3部分。它声明使用模型来设置值，但它几乎是试验和错误而没有进展。
setSize( 500,400 );
carList = new ArrayList<Auto>( );
ad = new AutoDisplay( carList );
setVisible( true );
ad.setEraseColor( getBackground( ) );
// fill carList with several cars
fillWithCars( );
}
// ***** 1. This method has been coded as an example
/** Fills the carList with hard-coded Auto objects
* The instance variable carList is the ArrayList
* to be filled with Auto objects
*/
public void fillWithCars()
{
// clear carList before adding cars
carList.clear();
// Reset the number of Autos to 0
// This is needed so that the animation feedback works correctly
Auto.clearNumberAutos();
Auto car1 = new Auto("BMW", 0, 0.0);
Auto car2 = new Auto("Ferrari", 100, 500.0);
Auto car3 = new Auto("Jeep", 1000, 90.0);
Auto car4 = new Auto("Ferrari", 10, 3.0);
Auto car5 = new Auto("BMW", 4000, 200.0);
Auto car6 = new Auto("Ferrari", 1000, 50.0);
carList.add(car1);
carList.add(car2);
carList.add(car3);
carList.add(car4);
carList.add(car5);
carList.add(car6);
animate();
}
// ***** 2. Student writes this method
/** Prints carList to console, elements are separated by a space
* The instance variable carList is the ArrayList to be printed
*/
public void printAutoList()
{
// Note: To animate the algorithm, put this method call as the
// last element in your for loop
// animate(car);
// where car is the variable name for the current Auto object
// as you loop through the ArrayList object
// Part 2 student code starts here:
System.out.println(carList);
Auto car;
for (int i = 0; i < carList.size();i++)
{
car=carList.get(i);
animate(car);
}
// Part 2 student code ends here.
}
// ***** 3. Student writes this method
/** Sets the model of all the elements in carList to parameter value
* The instance variable carList is the ArrayList to be modified
* @param model the model to assign to all Auto objects in carList
*/
public void setModelValues(String model)
{
// Note: To animate the algorithm, put this method call as the
// last statement in your for loop
// animate(car);
// where car is the variable name for the current Auto object
// as you loop through the ArrayList object
// Part 3 student code starts here:
for (Auto car: carList)
{
carList.add(carList.get(car).toString());
System.out.println(model.toString(odel.toArray()));
animate(car);
}
// Part 3 student code ends here.
}
// ***** 4. Student writes this method
/** Finds maximum number of miles driven
* Instance variable carList is the ArrayList to search
* @return the maximum miles driven by all the Auto objects
*/
public int findMaximumMilesDriven()
{
// Note: To animate the algorithm, put this method call as the
// last statement in your for loop
// animate(car, maximum);
// where car is the variable name for the current Auto object
// and maximum is the int variable storing the current maximum
// number of miles for all Auto elements you have already tested
// as you loop through the ArrayList object
// Part 4 student code starts here:
return 0; // replace this statement with your return statement
// Part 4 student code ends here.
}
// ***** 5. Student writes this method
/** Finds number of times parameter model is found in the carList
* Instance variable carList is the ArrayList in which we search
* @param model the model to count
* @return the number of times model was found
*/
public int countFound(String model)
{
// Note: To animate the algorithm, put this method call as the
// last statement in your for loop
// animate(car, num);
// where car is the variable name for the current Auto object
// and num is the int variable storing the current number of
// Auto elements whose model is equal to the method's parameter
// as you loop through the ArrayList object
// Part 5 student code starts here:
return 0; // replace this statement with your return statement
// Part 5 student code ends here.
}
public void startActivity( int act )
{
ad.setActivity( act );
boolean goodInput = false;
String answer = "";
String message = "";
switch( act )
{
case 0:
fillWithCars( );
JOptionPane.showMessageDialog( null, "carList filled with new values" );
break;
case 1:
printAutoList( );
JOptionPane.showMessageDialog( null, "carList printed" );
break;
case 2:
answer = JOptionPane.showInputDialog( null, "Enter a car model" );
if (answer != null )
{
ad.setSearchModel( answer );
setModelValues( answer );
if ( ad.getCurrentModelValuesSet( ) )
message = "\nYour result is correct";
else
message = "\nYour result is not correct";
JOptionPane.showMessageDialog( null, "car models set to " + answer + message );
}
break;
case 3:
int a = findMaximumMilesDriven( );
if ( a == ad.getCurrentMaximumMilesDriven( ) )
message = "\nYour result is correct";
else
message = "\nYour result is not correct";
JOptionPane.showMessageDialog( null, "The maximum number of miles driven is " + a + message );
break;
case 4:
answer = JOptionPane.showInputDialog( null, "Enter a car model" );
if ( answer != null )
{
ad.setSearchModel( answer );
int frequency = countFound( answer );
if ( frequency == ad.getCurrentCountModelFound( ) )
message = "\nYour result is correct";
else
message = "\nYour result is not correct";
if ( frequency > 1 )
JOptionPane.showMessageDialog( null, answer + " found " + frequency + " times" + message );
else if ( frequency == 1 )
JOptionPane.showMessageDialog( null, answer + " found " + frequency + " time" + message );
else
JOptionPane.showMessageDialog( null, answer + " not found" + message );
}
break;
}
enableButtons( );
}
public static Auto getCurrent( )
{
return current;
}
public static ArrayList getCarList( )
{
return carList;
}
private void animate( Auto au )
{
if ( ad.getActivity( ) == 1 || ad.getActivity( ) == 2 )
{
try
{
current = au;
ad.setCarList( carList );
ad.setCurrentAuto( au );
ad.setCurrentIndex( au.getIndex( ) );
repaint( );
Thread.sleep( 4000 );
}
catch ( InterruptedException e )
{
System.out.println( "IE Exception " + e.getMessage( ) );
System.out.println( e.toString( ) );
}
}
else
{
// call to animate has wrong number of arguments
JOptionPane.showMessageDialog( null, "Wrong number of arguments to animate method" );
System.exit( 1 );
}
}
private void animate( Auto au, int studentResult )
{
if ( ad.getActivity( ) == 3 || ad.getActivity( ) == 4 )
{
try
{
current = au;
ad.setCarList( carList );
ad.setCurrentAuto( au );
ad.setCurrentIndex( au.getIndex( ) );
ad.setStudentResult( studentResult );
repaint( );
Thread.sleep( 4000 );
}
catch ( InterruptedException e )
{
System.out.println( "IE Exception " + e.getMessage( ) );
System.out.println( e.toString( ) );
}
}
else
{
// call to animate has wrong number of arguments
JOptionPane.showMessageDialog( null, "Wrong number of arguments to animate method" );
System.exit( 1 );
}
}
private void animate( )
{
if ( ad.getActivity( ) == 0 )
{
try
{
ad.setCarList( carList );
repaint( );
Thread.sleep( 4000 );
}
catch ( InterruptedException e )
{
System.out.println( "IE Exception " + e.getMessage( ) );
System.out.println( e.toString( ) );
}
}
else
{
// call to animate has wrong number of arguments
JOptionPane.showMessageDialog( null, "Wrong number of arguments to animate method" );
System.exit( 1 );
}
}
public void paint( Graphics g )
{
if ( ( ( current != null ) || firstTime ) && ( ad.getActivity( ) != 0 ) )
{
super.paint( g );
if ( ad.getCurrentAuto( ) != null )
ad.updateAutoDisplay( current, g );
firstTime = false;
}
else if ( ad.getActivity( ) == 0 )
{
super.paint( g );
ad.updateAutoDisplay( g );
}
}
public static void main( String [] args )
{
app = new ArrayListPractice( );
app.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
}
public void disableButtons( )
{
fillValues.setEnabled( false );
printAutoList.setEnabled( false );
setValues.setEnabled( false );
countFrequency.setEnabled( false );
findMaximum.setEnabled( false );
}
public void enableButtons( )
{
fillValues.setEnabled( true );
printAutoList.setEnabled( true );
setValues.setEnabled( true );
countFrequency.setEnabled( true );
findMaximum.setEnabled( true );
}
private class ButtonHandler implements ActionListener
{
private boolean on = true;
public void actionPerformed( ActionEvent e )
{
printAutoListT t = new printAutoListT( app );
if ( e.getSource( ) == fillValues )
{
disableButtons( );
fillValues.requestFocus( );
ad.setActivity( 0 );
t.start( );
}
else if ( e.getSource( ) == printAutoList )
{
disableButtons( );
printAutoList.requestFocus( );
ad.setActivity( 1 );
t.start( );
}
else if ( e.getSource( ) == setValues )
{
disableButtons( );
setValues.requestFocus( );
ad.setActivity( 2 );
t.start( );
}
else if ( e.getSource( ) == findMaximum )
{
disableButtons( );
findMaximum.requestFocus( );
ad.setActivity( 3 );
t.start( );
}
else if ( e.getSource( ) == countFrequency )
{
disableButtons( );
countFrequency.requestFocus( );
ad.setActivity( 4 );
t.start( );
}
}
}
private class printAutoListT extends Thread
{
ArrayList<Auto> arr;
ArrayListPractice s1;
public printAutoListT ( ArrayListPractice s )
{
arr = ArrayListPractice.carList;
s1 = s;
}
public void run( )
{
startActivity( ad.getActivity( ) );
}
}
}
自动课程：
import java.text.DecimalFormat;
import java.awt.Graphics;
public class Auto
{
// Static instance variable - number of Auto objects references created
private static int numberAutos = 0;
// Instance variables
private String model; // model of auto
private int milesDriven; // number of miles driven
private double gallonsOfGas; // number of gallons of gas
private int index; // car number
// Default constructor:
// Initializes model to a blank String
// milesDriven are autoinitialized to 0, gallonsOfGas to 0.0
public Auto( )
{
model = "";
index = numberAutos;
numberAutos++;
}
// Overloaded constructor:
// Allows client to set beginning values for
// model, milesDriven, and gallonsOfGas.
// Calls mutator methods to validate new values.
public Auto( String startModel,
int startMilesDriven,
double startGallonsOfGas )
{
model = startModel;
setMilesDriven( startMilesDriven );
setGallonsOfGas( startGallonsOfGas );
index = numberAutos;
numberAutos++;
}
// Accessor method:
// Returns current value of index
public int getIndex( )
{
return index;
}
// Accessor method:
// Returns current value of model
public String getModel( )
{
return model;
}
// Accessor method:
// Returns current value of milesDriven
public int getMilesDriven( )
{
return milesDriven;
}
// Accessor method:
// Returns current value of gallonsOfGas
public double getGallonsOfGas( )
{
return gallonsOfGas;
}
// Mutator method:
// Allows client to set model
public void setModel( String newModel )
{
model = newModel;
}
// Mutator method:
// Allows client to set value of milesDriven
// prints an error message if new value is less than 0
public void setMilesDriven( int newMilesDriven )
{
if ( newMilesDriven >= 0 )
milesDriven = newMilesDriven;
else
{
System.err.println( "Miles driven must be at least 0." );
System.err.println( "Value not changed." );
}
}
// Mutator method:
// Allows client to set value of gallonsOfGas;
// prints an error message if new value is less than 0.0
public void setGallonsOfGas( double newGallonsOfGas )
{
if ( newGallonsOfGas >= 0.0 )
gallonsOfGas = newGallonsOfGas;
else
{
System.err.println( "Gallons of gas must be at least 0." );
System.err.println( "Value not changed." );
}
}
// Mutator method
// Allows client to add miles driven and gallons of gas used
// to current values;
// prints error messages if new values are less than 0
public void addMileage( int newMilesDriven,
double newGallonsOfGas )
{
if ( newMilesDriven < 0 )
{
System.err.println( "Miles driven must be at least 0." );
System.err.println( "Value not changed" );
return; // do not continue executing method
}
if ( newGallonsOfGas < 0.0 )
{
System.err.println( "Gallons of gas must positive." );
System.err.println( "Value not changed" );
return; // do not continue executing method
}
// ok to change values
milesDriven += newMilesDriven; // add newMilesDriven
gallonsOfGas += newGallonsOfGas; // add newGallonsOfGas
}
// Calculates mileage as miles per gallon.
// If no gallons of gas have been used, returns 0.0;
// Otherwise, returns miles per gallon
// as milesDriven / gallonsOfGas
public double calculateMilesPerGallon( )
{
if ( gallonsOfGas != 0.0 )
return milesDriven / gallonsOfGas;
else
return 0.0;
}
public static void clearNumberAutos( )
{
numberAutos = 0;
}
public String toString( )
{
DecimalFormat gallonsFormat = new DecimalFormat( "##.0" );
return "Model: " + model
+ " Miles driven: " + milesDriven
+ " Gallons of gas: "
+ gallonsFormat.format( gallonsOfGas );
}
public void draw( Graphics g, int startX, int endX, int y)
{}
} // end Auto class definition
任何帮助将不胜感激！谢谢！