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Decision Making in Java

Hey there! In this guide, we'll explore decision-making in Java. Decision-making structures allow you to execute different blocks of code based on certain conditions. Let's dive in!

  • Decision-making structures allow you to execute different blocks of code based on certain conditions.
  • Java provides several constructs for decision-making, including if, else, else if, and switch.

1. The if Statement​

Syntax:​

if (condition) {
// code to be executed if condition is true
}

Example:​

int num = 10; if (num > 0) {
System.out.println("The number is positive."); }

2. The if...else Statement​

Syntax:​

if (condition1) {     // code to be executed if condition1 is true 
} else { // code to be executed if condition1 is false
}

Example:​

int num = -5; if (num > 0) {     
System.out.println("The number is positive."); }
else {
System.out.println("The number is not positive."); }

3. The if...else if...else Statement​

Syntax:​

if (condition1) {     // code to be executed if condition1 is true 
} else if (condition2) { // code to be executed if condition2 is true
} else { // code to be executed if both conditions are false
}

Example:​

int num = 0; if (num > 0) {     
System.out.println("The number is positive."); }
else if (num < 0) {
System.out.println("The number is negative."); }
else {
System.out.println("The number is zero."); }

4. The switch Statement​

Syntax:​

switch (expression) {     
case value1: // code to be executed if expression == value1
break;
case value2: // code to be executed if expression == value2
break;
default: // code to be executed if expression doesn't match any case
}

Example:​

int day = 3; switch (day) {     
case 1:
System.out.println("Monday");
break;
case 2:
System.out.println("Tuesday");
break;
case 3:
System.out.println("Wednesday");
break;
default:
System.out.println("Not a valid day"); }

5. Nested if Statements​

Example:​

int num = 15; if (num > 10) {     
System.out.println("The number is greater than 10.");
if (num > 20) {
System.out.println("The number is also greater than 20.");
} }

6. Conditional Operators​

Java also supports conditional operators for compact decision-making.

Ternary Operator​

Syntax:​

(condition) ? expression1 : expression2;

Example:​

int num = 10; String result = (num > 0) ? "Positive" : "Non-positive";
System.out.println(result);

Understanding decision-making structures in Java is crucial for controlling the flow of your program and executing different actions based on conditions. Happy coding!