Using & Understanding the Main() Method

[psmith]

Could somebody please explain how to use the main() method properly.
I have read numerous books but none seem to help.

I have two classes - Payment and TestPayment.

In TestPayment I have the following code:

public class TestPayment
{
public static void main(String[] args)
{
// Create four Payment instances
Payment p1 = new Payment(2490, "Euros");
Payment p2 = new Payment(2490, "Euros");
Payment p3 = new Payment(2491, "Euros");
Payment p4 = new Payment(2490, "Pesos");
Payment p5 = new Payment(49, "Pesos");
Payment p6 = new Payment(9, "Pesos");
Payment p7 = new Payment(10, "Pesos");
}
}

In the Payment class I have the following method to create:

public boolean equals(Object o)
{
}
In here I have to check if the payments are the equal to each other,
firstly the amount, followed by the currency.

The amount is an int value(anAmount) and the currency a String value
(aCurrency)

How do I iterate through each Payment to see if they are equal or not?

Thanks in advance,

Paul

 

[Robert Klemme]

Could somebody please explain how to use the main() method properly.
I have read numerous books but none seem to help.

I have two classes - Payment and TestPayment.

It seems you have one class - a Java class (pun intended).

In TestPayment I have the following code:

public class TestPayment
{
public static void main(String[] args)
{
// Create four Payment instances
Payment p1 = new Payment(2490, "Euros");
Payment p2 = new Payment(2490, "Euros");
Payment p3 = new Payment(2491, "Euros");
Payment p4 = new Payment(2490, "Pesos");
Payment p5 = new Payment(49, "Pesos");
Payment p6 = new Payment(9, "Pesos");
Payment p7 = new Payment(10, "Pesos");
}
}

In the Payment class I have the following method to create:

public boolean equals(Object o)
{
}
In here I have to check if the payments are the equal to each other,
firstly the amount, followed by the currency.

The amount is an int value(anAmount) and the currency a String value
(aCurrency)

How do I iterate through each Payment to see if they are equal or not?

What does your textbook say about dealing with multiple instances of the
same type?

robert

 

[Michael Rauscher]

Could somebody please explain how to use the main() method properly.

Could you explain what your question (see below) has to do with the
main-method?

I have read numerous books but none seem to help.

None of the books you read told you how to use the main method? I don't
believe that.

I have two classes - Payment and TestPayment.

In TestPayment I have the following code:
....

In the Payment class I have the following method to create:

public boolean equals(Object o)
{
}
In here I have to check if the payments are the equal to each other,
firstly the amount, followed by the currency.

Remember to override hashCode, too.

The amount is an int value(anAmount) and the currency a String value
(aCurrency)

How do I iterate through each Payment to see if they are equal or not?

To iterate you'd need something to iterate on, e. g. an array or a List.

You could create such List e. g. via:

List<Payment> payments = Arrays.asList( new Payment(1234, "EUR"),
new Payment(5678, "EUR"),
... );

Then you could write a method that compares all payments in the list
with each other:

boolean areAllPaymentsEqual( List<Payment> payments ) {
if ( payments.size() == 0 )
return true;

Iterator<Payment> it = payments.iterator();
boolean result = true;
Payment firstPayment = it.next();
while ( result && it.hasNext() ) {
Payment secondPayment = it.next();
result = firstPayment.equals(secondPayment);
}
return result;
}

Bye
Michael