[public | private | protected | global] [override] [static] data_type method_name (input parameters) { // The body of the method }
public static Integer getInt() { return MY_INT; }
As in Java, methods that return values can also be run as a statement if their results are not assigned to another variable.
System.debug('Here is a note for the log.');
In Apex, all primitive data type arguments, such as Integer or String, are passed into methods by value. This fact means that any changes to the arguments exist only within the scope of the method. When the method returns, the changes to the arguments are lost.
Non-primitive data type arguments, such as sObjects, are passed into methods by reference. Therefore, when the method returns, the passed-in argument still references the same object as before the method call. Within the method, the reference can't be changed to point to another object but the values of the object's fields can be changed.
The following are examples of passing primitive and non-primitive data type arguments into methods.
Example: Passing Primitive Data Type Arguments
public class PassPrimitiveTypeExample { public static void debugStatusMessage() { String msg = 'Original value'; processString(msg); // The value of the msg variable didn't // change; it is still the old value. System.assertEquals(msg, 'Original value'); } public static void processString(String s) { s = 'Modified value'; } }
Example: Passing Non-Primitive Data Type Arguments
This example shows how a List argument is passed by reference into the reference() method and is modified. It then shows, in the referenceNew() method, that the List argument can’t be changed to point to another List object.
public class PassNonPrimitiveTypeExample { public static void createTemperatureHistory() { List<Integer> fillMe = new List<Integer>(); reference(fillMe); // The list is modified and contains five items // as expected. System.assertEquals(fillMe.size(),5); List<Integer> createMe = new List<Integer>(); referenceNew(createMe); // The list is not modified because it still points // to the original list, not the new list // that the method created. System.assertEquals(createMe.size(),0); } public static void reference(List<Integer> m) { // Add rounded temperatures for the last five days. m.add(70); m.add(68); m.add(75); m.add(80); m.add(82); } public static void referenceNew(List<Integer> m) { // Assign argument to a new List of // five temperature values. m = new List<Integer>{55, 59, 62, 60, 63}; } }