Conditional Statements in Java

The below article goes through the Conditional Statements in Java. It covers if, if-else, nested if-else, and switch statements with examples. 

Contents

• Introduction
• Conditional Statements in Java
  • If statement
  • If else statement
  • Nested If-Else Statements
• Switch Statement
  • Multiple case labels in a switch
• If else vs. Switch statements
• Conclusion

Introduction

Conditional Statements come under Control Structures in Java. As the same suggests, it controls the flow of the execution of the program. Controlling here means branching, decision-making, and iterating.

Generally, there are 3 types of Control Structures in Java:

• Conditional Statements or Decisional Statements (if, if-else, switch)
• Iteration Statements or Loops (for, while, do-while, for-each)
• Jump Statements (break, continue, return)

In this article, we aim to explain conditional statements in Java and their working with examples.

Conditional Statements in Java

Conditional statements in Java are the executable block of code (or branch to a specific code) dependent on certain conditions. These statements are also known as decision statements or selection statements in Java.

Following are the statements covered under conditional statements in Java:

• If statement
• If else statement
• Switch Statement

If Statement

If a statement executes a set of statements based upon certain conditions. The condition statement follows the if keyword.

Syntax:

if (condition)
{
//Statements to be executed
}

Working of if statement:

The if clause accepts a condition and executes the set of statements falling under it only when the condition evaluated is true. 

Instance: displaying a number as positive (statement) if the number is greater than zero (condition).

Example:

Output:

Also read: Variables in Java

If-Else Statement

If-Else statement is a control structure that selects or chooses a set of statements depending upon certain conditions. 

If statements are like a subset of if-else statements.

Syntax:

if (condition)
{
//Statements to be executed if condition satisfies
}
else
{
//Statements to be executed if the condition is not satisfied
}

Working of if-else statements:

Here, the if clause evaluates the expression. If it comes out as true, statements under if block gets executed. Else, statements under the else block get executed. As you can observe here, depending upon the condition some sets of statements are executed and some are bypassed. 

Note: An else clause should always come after the if clause. If not, then the compiler will generate an error stating “misplaced else”.

Read: Difference between JDK, JVM and JRE.

Instance: Display a number as positive or negative based upon the condition: if the number is greater than 0 or not.

Example:

Output:

Also Read: Java Hello World Program

Nested If-Else Statements

The nested if-else statements are statements that incorporate more than one if-else clause. 

Syntax:

if (condition)
{
//Statements set 1
}
else if (condition 2) 
{ 
//Statements set 2
}
 
. . .
 
else
{
//Statements to be executed if no condition is satisfied.
}

Example:

Output:

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Switch Statement

Unlike the if-else statement, the switch has multiple paths of execution. Moreover, it evaluates the expression based on some of the primitive types or class types and matches their value with its cases.

A switch can work well with a byte, char, short, and int primitive data types.

Syntax: 

switch (Expression)
{
case value 1: Statement 1;
case value 2: Statement 2;
case value 3: Statement 3;
.
.
.
case value n: Statement n;
Default: default statement;
}

Example:

Output:

Note: The break statement used in the above program is a jump statement that alters the flow of execution and jumps to a new set of statements.  Here, a break jump statement bypasses all the other cases and jumps out of a switch.

Also Read: Java Operators Explained

Multiple case labels in a switch

We can have multiple case labels in a switch statement. This type of switch case label is required when we want to perform the same task for a set of cases. 

Example:

Output:

Read: Arrays in Java

If-Else vs. Switch statements

The below table shows you the differences between if-else and switch statements in Java.

	If-Else	Switch
Flow of Execution	Can have only two possible paths of execution either if or else.	Can have multiple paths of execution in the forms of different cases.
Type of Outcome	Always evaluates an expression to a boolean value.	Can evaluate an expression to a byte, short, char, and int primitive type values.
Readability	Less readable in case of multiple if-else.	More readable in case of multiple cases.
Efficiency	It becomes less efficient in case of multiple if-else. Since it checks for every if/else and evaluates the corresponding statements.	More efficient working because once a valid match is found, the other cases are bypassed if handled carefully with a break statement.

Conclusion

Hope you enjoyed reading the above article and learned something new about conditional statements in Java. Share your thoughts and queries in the link below.

For more, Read: 8 Most Important Data Structures a Programmer Must Know

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