History and Development of Java: Functions, Conditionals and iterative statements

Learning Java is a basic today just like learning English. If you know English you can travel anywhere in the world. Similarly, if you know Java you can step into any aspect of programming and problem-solving. Java has wide usage in android and web apps development and much more. In our last few articles, we managed to bring you the basics of Java programming. So now let's dive deeper and know more about Java. In this article, we are going to read about functions. Functions are the basic building blocks of a program, we can never execute a program without having any function. This article is the third instalment of the ongoing java series. In this article, we are going to discuss library functions and some of the built-in function which is provided by the BlueJ. Apart from that the conditionals and iterative statements are also going to be included. All the program snippets are done in BlueJ code editor for Java. So now let's jump into the article and know what exactly are functions, conditionals and loops.

Built-in functions are those which are pre-installed and pre-defined in the platform which we are using for performing a programming language. 

      int a= Math.max(6,9);

      9

Math.min(): This function can be used to take out the smallest number between the two.

      int a=Math.min(6,9);

      6

Math.pow(): This function can be used to take out the raised power of the number.

      int a=Math.pow(2,3);

      8

Math.abs(): This function is used to take out the absolute value of a given number.

      int a=Math.abs(-5.673);

      5.673

Math.sqrt(): This function returns the square root of the given number.

      int a=Math.sqrt(36);

      6

Math.log(): This function returns the natural logarithmic value of a given number.

      int a=Math.log(4);

      0.602059991

Math.rint(): This function returns the exact value if the difference is less than 0.5 or else it returns the higher value.

      double a=Math.rint(7.34);

      7.0

      double a=Math.rint(7.68);

      8.0

Math.round(): This function returns the rounded off value.

      double a=Math.round(6.25);

      6.0

      double a=Math.round(-7.89);

      -8.0

Math.random(): This function returns a random value between 0 to 1. 

      double a=Math.random();

      0.2538751474867425368

Math.ceil(): This function returns themes higher value corresponding to the argument given.

      double a=Math.ceil(7.69);

      8.0

Math.floor(): This function returns the lowest nearer small integer corresponding to the given value.

      double a=Math.floor(7.98);

      7.0

In Java, it is possible to declare functions as per the user's requirement. The built-in functions and user-defined functions basically obey the same rules however the user has to define them as per its requirement in the whole program. As we know a function or method is a block of code which contains the mechanism of what is to be performed when called somewhere in the program. Some basic rules of user-defined function are:

1. A function name is an identifier i.e only letters, numbers and a special character '_' is only allowed.
2. A function name must not be a reserved keyword.
3. A function name must not exceed 128 characters.
4. A function name cannot start with numbers however numbers can be included in the middle or at the end.
5. No spaces or special characters are allowed however in case of space, '_' can be used.

Java follows every aspect of object-oriented programming. Every function must be included inside a class i.e they should be a part of the class. A function is declared by its name followed by parenthesis  '()'. At the time of declaring a method, the programmer has to declare what type of value does the function returns. In Java, return types can be int, float, double, char, String, Map, List etc are allowed. If the function doesn't return any value, then its default return type is void.

The programmer can use modifiers to define the access types whether it is public, private etc. The keyword static is used to define that the function can be accessed without creating objects. And at last inside the parenthesis, parameters are passed by declaring their types. A parameter is a value passed to a function. 

                   public static int sum(int arg1, int arg2){

The statements which can be used in decision making are called Conditional Statements. In a conditional statement, we use the if-else statements.

We use if statement, when we have to check for a specific condition the if statement performs a specific task when the condition provided, is true or else it ignores the condition.

Syntax

If the given condition provided in the above syntax will be true then Statement 1 and Statement 2 will be executed and if not then control passes to the next code written in the program and skips it.

When there is a group of tasks and a particular task has to be done, in this situation we use the only if statement. In this type of if statement we can use multiple if and can give multiple conditions, provided if the condition is true then the statement corresponding to the condition will be executed and the control will come out.

Syntax

For example, you need to check a number to be a single-digit, double-digit or triple-digit number.

Here if the condition satisfies then the statements present inside the if block will be executed and if not then it will automatically print the statement written in the else block.

Syntax

For example, you've to check whether a number is even or odd :

An if within an if is called a nested if statement. When there is two or more condition present after the execution of host conditions in this state we use nested if. 

Syntax

For example, you've to check the greatest number among the three :

We have just seen that whenever that is a condition or more than one possibility is present we use the if statement, but in many cases the if statement proves to be very much complicated.

For example, the nested if is much more complicated when its branches go deeper. That's why it is a bit difficult to recognise if statement. To solve this problem Java provides with one more built-in function which is the Switch Statement.

Java provides us with multiple branching selection statements which are known as the Switch Statement. This function successively compares the value with the Case, whenever the case is matched with the value, the following block of statements associated with the Case gets executed.

Syntax

For example, you've to do a menu-driven program to execute addition, subtraction, multiplication and division :

The statement which we right under the case must be terminated with a break. If we don't apply a break, the program will think that it has to proceed forward and it will execute the following cases also, that is why we use a break. When we use this break statement the control of the program come out from the Switch Statement. 

When no match is found the program automatically execute the Default case.

In programming, certain situations occur when the following task has to be repeated repeatedly. In those conditions we use Loops.

Loops are basically the functions which repeat the following task for a certain period. Basically, there are three types of loops used in Java :

Hope you enjoyed reading this Java tutorial article. In this article, the basics of java programming have been discussed. In the next article, we are bringing more exciting stuff. So, subscribe to our newsletter to stay tuned to our latest posts. 

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