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Concept
Methods are the simplest construct for abstraction
in Java. A method starts with a declaration that defines its
signature :
the name of the method, the number and types of the
formal parameters and the
return type .
The body of the method consists of local variable declarations and of statements.A method is
called or
invoked by writing the name of the method
followed by a list of values, called
actual parameters , one for
each formal parameter. A method can return a value or it can be declaredas
void if no value is returned.
These source code of these learning objects can be found in method.zip .
| LO | Topic | Java Files (.java) | Prerequisites |
| "A void method" | A void method | Method01 | |
| "A method returning a value" | A method returning a value | Method02 | |
| "Calling one method from another" | Calling one method from another | Method03 | 1, 2 |
| "Recursion" | Recursion | Method04 | 2 |
| "Calling methods on an object" | Calling methods on an object | Method05 | 2, * |
| "Calling a method on the same object" | Calling a method on the same object | Method06 | 5, * |
| "Objects as parameters" | Objects as parameters | Method07 | 5, * |
| "Returning objects" | Returning objects | Method08 | 7, * |
| "Returning locally instantiated objects" | Returning locally instantiated objects | Method09 | 8, * |
* This LO assumes knowledge of the declaration of classes and the instantiation of objects.
Concept When a method that is declared
void is called,
it allocates memory for its parameters and local variables, executesits statements and then returns. The call is a statement constructed
from the name of the method followed by a list of actual parameters.
Program: Method01.java
// Learning Object Method01
// void methodspublic class Method01 {
static void printMax(int a, int b) { int max;
if (a > b)
max = a; else
max = b; System.out.println(max);
}
public static void main(/*String[] args*/) {
int x = 10, y = 20; printMax(x, y);
Method01.printMax(10, y); }
}
The program computes the maximum of two integer values.
x and
y are allocated and initialized.x and
y .Method Area . The new activation record hides
the previous ones which are no longer accessible.max is allocated within the activation record.
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