Since Java is a general-purpose programming language, you'll need certain functions to be implemented and invoked on time for a successful application development. The block of code written to perform a certain dedicated function is known as a method. In this blog, you'll learn more on Methods in Java.<\/p>\n\n\n\n
Let\u2019s start learning!<\/strong><\/p>\n\n\n\n \n Java Programming Course<\/a>\n <\/p>\n Learn Java the right way! Our course teaches you essential programming skills, from coding basics to complex projects, setting you up for success in the tech industry.<\/p>\n A method is a set of code that can be named after the program scenario (E.g. For a program to add two numbers, method names can be sum ( ); ) and they can be invoked (called) at any point in a program to perform specific functions, by using the same name mentioned during declaration. <\/p>\n\n\n\n There are two types of methods in Java <\/p>\n\n\n\n These are built \u2013 in methods in Java, which are instantly available to use in your program. The Java class library will be present in java archive (i.e., *jar) file with Java Virtual Machine (JVM) and Java Runtime Environment. <\/p>\n\n\n\n Examples:<\/strong><\/p>\n\n\n\n Math functions \u2013 sqrt(), log(), min(), max(), avg(), sin(), cos(), tan(), round(),floor(), abs() etc.<\/p>\n\n\n\n String function \u2013 length( ), substring ( ), replace ( ), charAt ( ), indexOf ( ) , trim ( ) etc.<\/p>\n\n\n\n Sample Program: <\/strong><\/p>\n\n\n These methods are created by the programmers for their requirement as per the programming scenario \/ necessity.<\/p>\n\n\n\n SYNTAX: <\/strong><\/p>\n\n\n SYNTAX:<\/strong><\/p>\n\n\n SYNTAX:<\/strong><\/p>\n\n\n SYNTAX: <\/strong><\/p>\n\n\n A method must be declared within a class. It must contain the name of the method for identification, preceding with parentheses ( ). Java provides some pre-defined ( system defined) methods, for example System.out.println(), but user defined methods can also be created. <\/p>\n\n\n\n SYNTAX:<\/strong><\/p>\n\n\n A method in java is called by its name, we declare method with a name and common braces with semicolon;<\/p>\n\n\n\n Syntax: methodname ( );<\/p>\n\n\n\n Ex: javamethod( );<\/p>\n\n\n\n In the following example, javaMethod() is used to print a text (the function), when it is called:<\/p>\n\n\n\n Sample Program: <\/strong><\/p>\n\n\n There are two conditions where method returns to caller, they are:<\/strong><\/p>\n\n\n\n The information passed to the methods is known as Parameters. Parameters are similar to the variables we use in normal.<\/p>\n\n\n\n Parameters are mentioned after the method name, within the common braces. Multiple parameters can be added using comma separators. Similar to variable declaration.<\/p>\n\n\n\n The example below has a method that takes a String in a method:<\/p>\n\n\n We have learnt only void keyword in the method which means it should not return any value. If the value to be returned by the method then you can use data types such as int, char etc. So use the return keyword instead of void in the method: <\/p>\n\n\n\n In this example we are passing value 19 to the method to add it with 5: <\/p>\n\n\n OUTPUT:<\/strong> 24<\/p>\n\n\n\n In order to make static memory allocation and execution of the codes\/ methods we use STACK MEMORY in Java. Access to this memory is in Last-In-First-Out (LIFO) order as the stack by nature follows LIFO. A new block on stack top is created when we call new method that contains specific values related to that method, like parameters and reference objects. After method execution is complete, its stack frame is cleared, the execution returns back to the calling method and the empty pace will be available for the upcoming method.<\/p>\n\n\n\n Before we conclude this article, let's quickly summarize the features of the stack memory.<\/p>\n\n\n\nWhat is a Method? <\/strong><\/h2>\n\n\n\n
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Different Types of Methods in Java <\/strong><\/h2>\n\n\n\n
1. Pre \u2013 Defined Methods\/ Standard Library Methods\/System defined Methods: <\/strong><\/h3>\n\n\n\n
\npublic class Main \n{\npublic static void main(String[] args) \n{\nString targetString = "Java is fun to learn";\nString str1= "JAVA";\nString str 2= "Java";\nString str 3 = " Hello Java ";\nSystem.out.println("Checking Length: "+ targetString.length());\nchar [] charArray = str2.toCharArray();\nSystem.out.println("Size of char array: " + charArray.length);\nSystem.out.println("Printing last element of array: " + charArray[3]);\n}\n}\n\n<\/pre><\/div>\n\n\n2. User \u2013 defined Methods: <\/strong><\/h3>\n\n\n\n
2.1 Method with returning a value<\/strong><\/h4>\n\n\n\n
2.1.1 Calling method by invoking Object<\/strong><\/h4>\n\n\n\n
\nWrite Method\n\/\/ Before main Method\naccessModifier returnType methodName(Parameters)\n{\nStatements\n\u2014\u2014\u2014\n\u2014\u2014\u2014\n\u2014\u2014\u2014\n}\n--------------------------------------------------------------------\n\/\/After main method\nCall Method\n\/\/Create Object\nClassName objectName = new ClassName( );\n\/\/Call Method by invoking object\ndataType variableName = object.method(values..);\nor\nSystem.out.println(object.method( ));\n\n<\/pre><\/div>\n\n\n2.1.2 Calling method without invoking Object<\/strong><\/h4>\n\n\n\n
\naccessModifier nonAccessModifier returnType methodName(Parameters)\n{\nStatements\n\u2014\u2014\u2014\u2014\n\u2014\u2014\u2014\u2014\n\u2014\u2014\u2014\u2014\n}\nCall Method\ndataType variableName = methodName(values);\nor\nSystem.out.println(methodname(values);\n\n<\/pre><\/div>\n\n\n2.2 Method without returning any value<\/strong><\/h4>\n\n\n\n
2.2.1 Calling method by invoking Object<\/strong><\/h4>\n\n\n\n
\naccessModifier returnTypeNothing methodName(parameters)\n{\nStatements\n\u2014\u2014\u2014-\n\u2014\u2014\u2014-\n\u2014\u2014\u2014\n}\n\/\/Create Object\nClassName objectName = new ClassName();\n\n\/\/Call Method\nobject.method(values);\n\n<\/pre><\/div>\n\n\n2.2.2 Calling method without invoking Object<\/strong><\/h4>\n\n\n\n
\naccessModifier nonAccessModifier returnTypeNothing methoName(Parameters){\nStatements\n\u2014\u2014\u2014\n\u2014\u2014\u2014\n\u2014\u2014\u2014\n}\nCall method\nmethodName(values);\n\n<\/pre><\/div>\n\n\nHow to Create a Method? <\/strong><\/h2>\n\n\n\n
\npublic class Main \n{\n static void mydemo() \n{\n \/\/ code to be executed\n }\n }\n Where, mydemo( ) is method name\n\n<\/pre><\/div>\n\n\nHow to call a Method? (Method Calling)<\/strong><\/h2>\n\n\n\n
\npublic class Main \n{\n static void javaMethod()\n {\n System.out.println(" Java is easy to learn ");\n }\n public static void main(String[] args)\n {\n javaMethod();\n }\n}\n \n\n<\/pre><\/div>\n\n\n\n
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Method Parameters<\/strong><\/h2>\n\n\n\n
\npublic class Main {\n static void myMethod(String fname) {\n System.out.println(fname + " Khan");\n }\n\n public static void main(String[] args) {\n myMethod("Salman");\n myMethod("Shahrukh");\n myMethod("Aamir");\n }\n}\n\n<\/pre><\/div>\n\n\nMethods with multiple parameters: <\/strong><\/h4>\n\n\n
\npublic class Main {\n static void myMethod(String fname, int age) {\n System.out.println(fname + " is " + age);\n }\n\n public static void main(String[] args) {\n myMethod("Sneha", 25);\n myMethod("Sanjana", 21);\n myMethod("Anju", 20);\n }\n}\n\n<\/pre><\/div>\n\n\nReturn Values:<\/strong><\/h4>\n\n\n\n
\npublic class Main\n {\n static int sum(int x) \n{\n return 5 + x;\n }\n public static void main(String[] args) \n{\n System.out.println(sum(19));\n }\n}\n\n<\/pre><\/div>\n\n\nMemory Allocation for Method Calls <\/strong><\/h2>\n\n\n\n
Key Features of Stack Memory<\/strong><\/h4>\n\n\n\n
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Example Program to understand Memory Allocation:<\/strong><\/h4>\n\n\n
\nclass Person {\n int id;\n String name;\n\n public Person(int id, String name) {\n this.id = id;\n this.name = name;\n }\n}\n\npublic class PersonBuilder {\n private static Person buildPerson(int id, String name) {\n return new Person(id, name);\n }\n\n public static void main(String[] args) {\n int id = 23;\n String name = "John";\n Person person = null;\n person = buildPerson(id, name);\n }\n}\n\n<\/pre><\/div>\n\n\n\n
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Summary<\/strong><\/h2>\n\n\n\n