public class MyHelloWorld { }
public static void applyDiscount(Book__c[] books) { for (Book__c b :books){ b.Price__c *= 0.9; } }
This method is called applyDiscount, and it is both public and static. Because it is a static method, you don't need to create an instance of the class to access the method—you can just use the name of the class followed by a dot (.) and the name of the method. For more information, see Static and Instance Methods, Variables, and Initialization Code.
This method takes one parameter, a list of Book records, which is assigned to the variable books. Notice the __c in the object name Book__c. This indicates that it is a custom object that you created. Standard objects that are provided in the Salesforce application, such as Account, don't end with this postfix.
The next section of code contains the rest of the method definition:
for (Book__c b :books){
b.Price__c *= 0.9;
}
Notice the __c after the field name Price__c. This indicates it is a custom field that you created. Standard fields that are provided by default in Salesforce are accessed using the same type of dot notation but without the __c, for example, Name doesn't end with __c in Book__c.Name. The statement b.Price__c *= 0.9; takes the old value of b.Price__c, multiplies it by 0.9, which means its value will be discounted by 10%, and then stores the new value into the b.Price__c field. The *= operator is a shortcut. Another way to write this statement is b.Price__c = b.Price__c * 0.9;. See Expression Operators.
public class MyHelloWorld { public static void applyDiscount(Book__c[] books) { for (Book__c b :books){ b.Price__c *= 0.9; } } }