View Discussion Show Improve Article Save Article View Discussion Improve Article Save Article There are different ways in which parameter data can be passed into and out of methods and functions. Let us assume that a function B() is called from another function A(). In this case A is called the “caller function” and B is called the “called function or callee function”. Also, the arguments which A sends to B are called actual arguments and the parameters of B are called formal arguments. Types of parameters:Formal Parameter: A variable and its type as they appear in the prototype of the function or method. Syntax: function_name(datatype variable_name)Actual Parameter: The variable or expression corresponding to a formal parameter that appears in the function or method call in the calling environment. Syntax: func_name(variable name(s));Important methods of Parameter Passing 1. Pass By Value: Changes made to formal parameter do not get transmitted back to the caller. Any modifications to the formal parameter variable inside the called function or method affect only the separate storage location and will not be reflected in the actual parameter in the calling environment. This method is also called ascall by
value.  Example: Javaclass CallByValue { public static void example(int x, int y) { x++; y++; } } public class Main { public static void main(String[] args) { int a = 10; int b = 20; CallByValue object = new CallByValue(); System.out.println("Value of a: " + a + " & b: " + b); object.example(a, b); System.out.println("Value of a: " + a + " & b: " + b); } } Output: Value of a: 10 & b: 20 Value of a: 10 & b: 20Shortcomings:
2. Call by reference(aliasing): Changes made to formal parameter do get transmitted back to the caller through parameter passing. Any changes to the formal parameter are reflected in the actual parameter in the calling environment as formal parameter receives a reference (or pointer) to the actual data. This method is also called as call by reference. This method is efficient in both time and space. Example Javaclass CallByReference { int a, b; CallByReference(int x, int y) { a = x; b = y; } void ChangeValue(CallByReference obj) { obj.a += 10; obj.b += 20; } } public class Main { public static void main(String[] args) { CallByReference object = new CallByReference(10, 20); System.out.println("Value of a: " + object.a + " & b: " + object.b); object.ChangeValue(object); System.out.println("Value of a: " + object.a + " & b: " + object.b); } } Output: Value of a: 10 & b: 20 Value of a: 20 & b: 40Please note that when we pass a reference, a new reference variable to the same object is created. So we can only change members of the object whose reference is passed. We cannot change the reference to refer to some other object as the received reference is a copy of the original reference. Please see example 2 in Java is Strictly Pass by Value! How do you declare a method using parameters?Parameters and Arguments
Information can be passed to methods as parameter. Parameters act as variables inside the method. Parameters are specified after the method name, inside the parentheses. You can add as many parameters as you want, just separate them with a comma.
Can methods take parameters?The parameters are used in the method body and at runtime will take on the values of the arguments that are passed in. Note: Parameters refers to the list of variables in a method declaration. Arguments are the actual values that are passed in when the method is invoked.
What is calling parameter?The term parameter (sometimes called formal parameter) is often used to refer to the variable as found in the function definition, while argument (sometimes called actual parameter) refers to the actual input supplied at function call.
How do you call a method in a variable name in Java?You could try something like: Method m = obj. getClass(). getMethod("methodName" + MyVar); m.
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