Solved

Posted on 2006-11-12
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I am refining an Elevator Modal and now I am trying to add some exceptions but am having problems. Specifically, I am having trouble addding an ElevatorFullEception to the code below:

__Code__

public class Elevator {
int capacity = 10;
int num_floors = 7;

public int passengers;
public int current_floor;
static int cycle_count = 0;
int print_floor = 0;

// Direction of movement
private boolean dir_up;

// switched to boolean array to reflect calls to a particular floor
// if you think of a real elevator it stops whether one person presses
// the button or ten people press it.
public boolean [] req_per_floor = new boolean[7];

// records the number of passengers who want to head to a floor
public int [] pass_to_floor ={0,2,1,0,0,0,0};

//Creates
public static Floor floors[] = new Floor[7];

//class constructor inserted here.
public Elevator() {
current_floor = 0;
dir_up = true;
passengers = 0;
}

/** Main Method
* @param args
*
*/
public static void main(String[] args){
Elevator myElevator = new Elevator();

//consturct som new floors
for (int f =0; f < 6; f++){//might have to be seven
floors[f] = new Floor();
}

//set passengers waiting
floors[1].queued_passengers = 3;
floors[2].queued_passengers = 2;
floors[3].queued_passengers = 1;
floors[5].queued_passengers = 4;
floors[6].queued_passengers = 2; // should thow exceptions

System.out.println(myElevator);
myElevator.move();
}

//#4 move method
public void move(){
while (cycle_count <= 2){
if(dir_up == true){
current_floor = current_floor +1;
}
else {
current_floor = current_floor -1;
}
if(passengers < capacity){
if(floors[current_floor].queued_passengers > 0){
stop();
}
}
//reverses dirction at bottom floor
if (current_floor == 0){dir_up = true;}
if (current_floor == 6){dir_up = false;}
if (current_floor == 6){cycle_count++;}
}
}
/**Overide the toString() from java.lang.Object
* @return A string reporting the elevator's state at each floor.
*/
public String toString(){
print_floor = current_floor + 1;
return "Currently "+passengers +" passengers are onboard."+ "\n"+"Current floor :" + print_floor ;
}

/** Stops the Elevator at each floor.
* @param print_floor
* @return No return value
*/
public void stop(){
System.out.println("stop!");

if(pass_to_floor[current_floor] >= 1){
disembark_passenger();
}
if(req_per_floor[current_floor] == true ){
try{
boardPassenger();
}catch (ElevatorFullException myElevator){
System.out.println("ElevatorFullEception");
}

}
print_floor = current_floor + 1;
}

/** Board passanger method
* @return No return value
*/
public void boardPassenger(){
if(floors[current_floor].queued_passengers == 0){
move();
}

while(passengers <= capacity){
floors[current_floor].queued_passengers = floors[current_floor].queued_passengers - 1;
passengers++;
pass_to_floor[0]++;
}
}

//req_per_floor[current_floor]--;

/** Disembark passenger method
* @return No return value
*/
public void disembark_passenger(){
passengers = passengers - 1;
pass_to_floor[current_floor]--;
}

public void registerRequest(){
if (floors[current_floor].queued_passengers >= 1){
req_per_floor[current_floor]= true;
}
else{
req_per_floor[current_floor]= false;
}
}

}
//end class Elevator

public class Floor {

public int queued_passengers;

int i = myElevator.pass_to_floor[myElevator.current_floor];
if (i > 0){
myElevator.passengers = myElevator.passengers - 1;
}
return;
}
}

// end Floor class

import java.lang.Exception ;
public class ElevatorFullException extends Exception {
public ElevatorFullException(){}
//public ElevatorFullException (String x){
//      super(x);
public ElevatorFullException (Elevator myElevator){
if(myElevator.passengers >= myElevator.capacity){
myElevator.move();
}
}

public String toString() {
}
public String getMessage() {
return "Notice: The Elevator is now full of passengers.";
}
}

__END__

Could someone please point out what I am doing wrong and show me how I might correct it?

Thanks,

-mox
0
Question by:chinamox
• 4

LVL 23

Expert Comment

ID: 17925526
try using something like this (wherever you want to throw this exception):

throw new ElevatorFullException(this); // Will throw ElevatorFullException from Elevator class.
0

LVL 24

Accepted Solution

sciuriware earned 2000 total points
ID: 17925545
while(passengers <= capacity){
floors[current_floor].queued_passengers = floors[current_floor].queued_passengers - 1;
passengers++;
pass_to_floor[0]++;
}
}
Enter here:
if(passengers >= capacity)
{
throw new ElevatorFullException();
}

The code in the exception itself is in a wrong place.

Then,

public void boardPassenger(){

should be

public void boardPassenger() throws ElevatorFullException
{

An exception is thrown and caught, it should not interfere with anything else
that the arguments you may give it.

;JOOP!
0

LVL 24

Expert Comment

ID: 17925552
A-S, you type quicker, but I type more.

I suspect a misconception of the deployment of exceptions.

;JOOP!
0

Author Comment

ID: 17927205
Thank you both.  sciurware, why do you 'expect a misconception of the deployment of exceptions?'
0

LVL 24

Expert Comment

ID: 17927799
Because the coding inside the ElevatorFullException should not be there.

;JOOP!
0

LVL 24

Expert Comment

ID: 17928386
:)
0

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