What are Decision Making Statements in Java? A Complete Guide

Decision Making Statements in Java are fundamental constructs that allow programmers to control the flow of their code based on certain conditions. These statements are crucial for implementing logic that makes the program more dynamic and responsive to different scenarios. 

According to Glassdoor, the average salary for a Java Developer is £64,560 per year in London, United Kingdom. Decision Making statements play a crucial role in making Java programs more intelligent and capable of adapting to changing inputs or user interactions, enhancing the overall functionality and efficiency of the applications. This blog will discuss various Decision Making Statements in Java that enable Java programmers to manage program flow according to specific conditions. 

Table of Contents 

1) A brief introduction to Decision Making Statements in Java 

2) Decision Making Statements in Java 

       a) if statement 

       b) if-else statement 

       c) if-else-if ladder 

       d) Nested if statements 

       e) switch statement 

3) Conclusion 

A brief introduction to Decision Making Statements in Java 

Java's Decision Making statements are essential programming components that enable developers to regulate code execution based on specific conditions. These statements enable Java programs to make informed choices and adapt to different scenarios dynamically. The most basic decision-making statement is the "if" statement, which executes a block of code only if a specified condition evaluates to true. 

By leveraging Decision Making Statements, developers can introduce logic and intelligence into their Java programs, making them more interactive and responsive to user inputs or changing data. These constructs are crucial for creating efficient and versatile applications, as they empower developers to handle diverse situations gracefully. 

Decision Making Statements in Java 

Following are a few Decision Making Statements in Java with examples:
 

if statement 

“If statement” executes a block of code if a condition is true. The "if statement" is a fundamental decision-making construct in Java that enables developers to selectively execute a block of code based on a given condition. The condition is specified within the parentheses following the "if" keyword. If the condition evaluates to true, the code block enclosed within curly braces immediately following the "if" statement is executed; otherwise, it is bypassed. 

Example code:
 

Output: 

The number is greater than 5. 

End of the program. 

In the example code, we have an integer variable 'number' with a value of 10. The if statement checks if the 'number' is greater than 5, which evaluates to true. Thus, the message "The number is greater than 5." is printed, followed by "End of the program." The "if statement" is a powerful tool for conditional execution and allows developers to make dynamic decisions based on varying conditions in their Java programs. 

if-else statement 

The "if-else statement" in Java is an extension of the basic "if statement" that allows developers to execute different blocks of code based on a given condition. If the condition specified in the "if" part evaluates to true, the code block within the corresponding curly braces is executed. However, if the condition is false, the code block within the "else" part is executed instead. 

Example code: 
 

Output: 

The number is greater than 5. 

End of the program. 

In the example code, the integer variable 'number' has a value of 10. The if-else statement checks if the 'number' is greater than 5, which is true. Consequently, the message "The number is greater than 5." is printed. The "else" part is skipped, and the program proceeds to print "End of the program." The if-else statement is a crucial tool for handling two distinct cases and making decisions based on the outcome of a condition in Java programs. 

if-else-if ladder 

The "if-else-if ladder" in Java is a sequence of conditional statements that allow developers to check multiple conditions one by one and execute the corresponding block of code based on the first true condition encountered. Each "if" condition is followed by an "else if" condition, except for the last one, which can be an "else" statement if none of the previous conditions evaluates to true. 

Example code: 
 

Output: 

The number is positive. 

End of the program. 

In the example code, the integer variable 'number' has a value of 10. The if-else-if ladder first checks if the 'number' is greater than 0, which is true, so it prints "The number is positive." The "else if" and "else" parts are skipped, and the program proceeds to print "End of the program." The if-else-if ladder is a powerful tool for handling multiple conditions in Java, enabling developers to execute the appropriate code block based on varying situations. 

Nested if statements 

Nested if statements in Java allow developers to create multiple levels of conditions by placing if statements within other if statements. This construct helps handle complex decision-making scenarios where certain conditions depend on the outcome of inner conditions. Each inner if statement is executed only if its parent condition evaluates to true. 

Example code:
 

Output: 

The number is positive and even. 

End of the program. 

In the example code, the integer variable 'number' has a value of 10. The nested if statements first check if the 'number' is greater than 0, which is true. Then, it checks if 'number' is even, and since it is, the message "The number is positive and even." is printed. The outer else part is skipped, and the program proceeds to print "End of the program." Nested-if statements provide a flexible way to handle intricate conditional logic in Java programs. 

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switch statement 

The "switch statement" in Java is a decision-making construct that allows developers to choose one of many code blocks to execute based on the value of a specific expression. The expression's value is evaluated, and the switch statement matches it against the constant values specified in each "case" label. When a matching value is found, the corresponding block of code is executed. If no case matches the expression's value, the "default" block, if present, is executed. 

Example code: 

Output: 

Today is Tuesday. 

In the example code, the integer variable 'dayOfWeek' has a value of 3, representing Tuesday. The switch statement matches this value with the "case 3" label and executes the corresponding code block, assigning "Tuesday" to the 'dayName' variable. The program then prints, "Today is Tuesday." The switch statement is an efficient way to handle multiple possible cases based on the value of an expression in Java programs. 

Ternary operator 

The ternary operator in Java is a concise way to write simple if-else statements in a single line. It allows developers to assign a value to a variable based on a condition, making code more compact and readable. The syntax of the ternary operator consists of three parts: the condition, the value if true (before the "?" symbol), and the value if false (after the ":" symbol). 

Example code: 
 

Output: 

The number is: Greater than 5 

In the example code, the integer variable ‘number’ has a value of 10. The ternary operator checks if the ‘number’ is greater than 5, which evaluates to true. Consequently, the value "Greater than 5" is assigned to the ‘result’ variable. The program then prints, "The number is: Greater than 5." The ternary operator is a powerful tool for streamlining simple conditional assignments in Java, enhancing code readability and conciseness. 

Multi-way ternary operator (Java 12+) 

In Java 12 and later versions, the switch expression can be used as a multi-way ternary operator, providing a more concise and expressive way to perform conditional assignments. Instead of using multiple if-else or ternary operators for multiple conditions, developers can use the switch expression to handle various cases elegantly. 

Example code:
 

Output: 

The number is: Three 

In the example code, the integer variable ‘number’ has a value of 3. The switch expression matches this value with the corresponding case label and assigns the appropriate value to the ‘result’ variable. In this case, "Three" is assigned to ‘result’, and the program prints "The number is: Three." The switch expression as a multi-way ternary operator simplifies code and improves readability, especially when dealing with multiple conditions in Java programs. 

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if-else with initialisation (Java 12+) 

In Java 12 and later versions, developers can use the if-else construct with variable initialisation, providing a more concise way to initialise variables based on conditions. This feature streamlines the code by combining variable declaration and initialisation with conditional checks in a single statement. 

Example code: 
 

Output: 

The number is: Greater than 5 

In the example code, the integer variable ‘number’ has a value of 10. The if-else construct with variable initialisation checks if the ‘number’ is greater than 5, which evaluates to true. Consequently, the value "Greater than 5" is assigned to the ‘result’ variable. The program then prints, "The number is: Greater than 5." This feature simplifies code and enhances readability, making it easier to handle conditional variable initialisation in Java programs. 

Enhanced switch statements (Java 12+) 

In Java 12 and later versions, enhanced switch statements offer a more concise syntax for handling multiple cases within a switch block. With this enhancement, developers can use "case" labels directly as expressions, simplifying the code and making it more readable. 

Example code:

Output: 

Today is Tuesday. 

In the example code, the integer variable ‘dayOfWeek’ has a value of 3, representing Tuesday. The enhanced switch statement directly assigns the matching day name to the ‘dayName’ variable. The program then prints, "Today is Tuesday." This enhancement simplifies switch statements and enhances code readability in Java, especially when dealing with a large number of cases.
 

Conclusion 

In summary, Decision Making Statements in Java programming are essential as they control the program's flow and implement conditional logic. Whether using if, switch, or ternary operators, mastering these constructs is crucial in creating efficient, dynamic, and intelligent Java applications. Understanding these statements empowers developers to make informed choices and build robust software solutions. 

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