How to make methods in java

Introduction to Java
The complete History of Java Programming Language
C++ vs Java vs Python
How to Download and Install Java for 64 bit machine?
Setting up the environment in Java
How to Download and Install Eclipse on Windows?
JDK in Java
How JVM Works – JVM Architecture?
Differences between JDK, JRE and JVM
Just In Time Compiler
Difference between JIT and JVM in Java
Difference between Byte Code and Machine Code
How is Java platform independent?

Decision Making in Java (if, if-else, switch, break, continue, jump)
Java if statement with Examples
Java if-else
Java if-else-if ladder with Examples
Loops in Java
For Loop in Java
Java while loop with Examples
Java do-while loop with Examples
For-each loop in Java
Continue Statement in Java
Break statement in Java
Usage of Break keyword in Java
return keyword in Java

Object Oriented Programming (OOPs) Concept in Java
Why Java is not a purely Object-Oriented Language?
Classes and Objects in Java
Naming Conventions in Java
Java Methods
Access Modifiers in Java
Java Constructors
Four Main Object Oriented Programming Concepts of Java
Inheritance in Java
Abstraction in Java
Encapsulation in Java
Polymorphism in Java
Interfaces in Java
‘this’ reference in Java

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Java Methods

A method is a block of code which only runs when it is called.

You can pass data, known as parameters, into a method.

Methods are used to perform certain actions, and they are also known as functions.

Why use methods? To reuse code: define the code once, and use it many times.

Create a Method

A method must be declared within a class. It is defined with the name of the method, followed by parentheses (). Java provides some pre-defined methods, such as System.out.println() , but you can also create your own methods to perform certain actions:

Example

Create a method inside Main:

Example Explained

myMethod() is the name of the method
static means that the method belongs to the Main class and not an object of the Main class. You will learn more about objects and how to access methods through objects later in this tutorial.
void means that this method does not have a return value. You will learn more about return values later in this chapter

Call a Method

To call a method in Java, write the method’s name followed by two parentheses () and a semicolon;

In the following example, myMethod() is used to print a text (the action), when it is called:

Example

Inside main , call the myMethod() method:

public class Main < static void myMethod() < System.out.println("I just got executed!"); >public static void main(String[] args) < myMethod(); >> // Outputs "I just got executed!"

A method can also be called multiple times:

Example

public class Main < static void myMethod() < System.out.println("I just got executed!"); >public static void main(String[] args) < myMethod(); myMethod(); myMethod(); >> // I just got executed! // I just got executed! // I just got executed!

In the next chapter, Method Parameters, you will learn how to pass data (parameters) into a method.

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Methods in Java

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The way it does all of that is by using a design model, a database-independent image of the schema, which can be shared in a team using GIT and compared or deployed on to any database.

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We’re looking for a new Java technical editor to help review new articles for the site.

1. Introduction

In Java, methods are where we define the business logic of an application. They define the interactions among the data enclosed in an object.

In this tutorial, we’ll go through the syntax of Java methods, the definition of the method signature, and how to call and overload methods.

2. Method Syntax

First, a method consists of six parts:

Access modifier: optionally we can specify from wherein the code one can access the method
Return type: the type of the value returned by the method, if any
Method identifier: the name we give to the method
Parameter list: an optional comma-separated list of inputs for the method
Exception list: an optional list of exceptions the method can throw
Body: definition of the logic (can be empty)

Let’s take a closer look at each of these six parts of a Java method.

2.1. Access Modifier

The access modifier allows us to specify which objects can have access to the method. There are four possible access modifiers: public, protected, private, and default (also called package-private).

A method can also include the static keyword before or after the access modifier. This means that the method belongs to the class and not to the instances, and therefore, we can call the method without creating an instance of the class. Methods without the static keyword are known as instance methods and may only be invoked on an instance of the class.

Regarding performance, a static method will be loaded into memory just once – during class loading – and are thus more memory-efficient.

2.2. Return Type

Methods can return data to the code where they have been called from. A method can return a primitive value or an object reference, or it can return nothing if we use the void keyword as the return type.

Let’s see an example of a void method:

public void printFullName(String firstName, String lastName)

If we declare a return type, then we have to specify a return statement in the method body. Once the return statement has been executed, the execution of the method body will be finished and if there are more statements, these won’t be processed.

On the other hand, a void method doesn’t return any value and, thus, does not have a return statement.

2.3. Method Identifier

The method identifier is the name we assign to a method specification. It is a good practice to use an informative and descriptive name. It’s worth mentioning that a method identifier can have at most 65536 characters (a long name though).

2.4. Parameter List

We can specify input values for a method in its parameter list, which is enclosed in parentheses. A method can have anywhere from 0 to 255 parameters that are delimited by commas. A parameter can be an object, a primitive or an enumeration. We can use Java annotations at the method parameter level (for example the Spring annotation @RequestParam).

2.5. Exception List

We can specify which exceptions are thrown by a method by using the throws clause. In the case of a checked exception, either we must enclose the code in a try-catch clause or we must provide a throws clause in the method signature.

So, let’s take a look at a more complex variant of our previous method, which throws a checked exception:

public void writeName(String name) throws IOException

2.6. Method Body

The last part of a Java method is the method body, which contains the logic we want to execute. In the method body, we can write as many lines of code as we want — or none at all in the case of static methods. If our method declares a return type, then the method body must contain a return statement.

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3. Method Signature

As per its definition, a method signature is comprised of only two components — the method’s name and parameter list.

So, let’s write a simple method:

public String getName(String firstName, String lastName)

The signature of this method is getName(String firstName, String lastName).

The method identifier can be any identifier. However, if we follow common Java coding conventions, the method identifier should be a verb in lowercase that can be followed by adjectives and/or nouns.

4. Calling a Method

Now, let’s explore how to call a method in Java. Following the previous example, let’s suppose that those methods are enclosed in a Java class called PersonName:

Since our getName method is an instance method and not a static method, in order to call the method getName, we need to create an instance of the class PersonName:

PersonName personName = new PersonName(); String fullName = personName.getName("Alan", "Turing");

As we can see, we use the created object to call the getName method.

Finally, let’s take a look at how to call a static method. In the case of a static method, we don’t need a class instance to make the call. Instead, we invoke the method with its name prefixed by the class name.

Let’s demonstrate using a variant of the previous example:

In this case, the method call is:

String fullName = PersonName.getName("Alan", "Turing");

5. Method Overloading

Java allows us to have two or more methods with the same identifier but different parameter list — different method signatures. In this case, we say that the method is overloaded. Let’s go with an example:

public String getName(String firstName, String lastName) < return getName(firstName, "", lastName); >public String getName(String firstName, String middleName, String lastName) < if (!middleName.isEqualsTo("")) < return firstName + " " + lastName; >return firstName + " " + middleName + " " + lastName; >

Method overloading is useful for cases like the one in the example, where we can have a method implementing a simplified version of the same functionality.

Finally, a good design habit is to ensure that overloaded methods behave in a similar manner. Otherwise, the code will be confusing if a method with the same identifier behaves in a different way.

6. Conclusion

In this tutorial, we’ve explored the parts of Java syntax involved when specifying a method in Java.

In particular, we went through the access modifier, the return type, the method identifier, the parameter list, the exception list, and the method body. Then we saw the definition of the method signature, how to call a method, and how to overload a method.

As usual, the code seen here is available over on GitHub.

Slow MySQL query performance is all too common. Of course it is. A good way to go is, naturally, a dedicated profiler that actually understands the ins and outs of MySQL.

Critically, it has very minimal impact on your server’s performance, with most of the profiling work done separately — so it needs no server changes, agents or separate services.

Basically, you install the desktop application, connect to your MySQL server, hit the record button, and you’ll have results within minutes:

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