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Conditionals and Control Flow

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else Statement

The else statement executes a block of code when the condition inside the if statement is false. The else statement is always the last condition.

boolean condition1 = false;


if (condition1){
    System.out.println("condition1 is true");
}
else{
    System.out.println("condition1 is not true");
}
// Prints: condition1 is not true

else if Statements

else-if statements can be chained together to check multiple conditions. Once a condition is true, a code block will be executed and the conditional statement will be exited.

There can be multiple else-if statements in a single conditional statement.

int testScore = 76;
char grade;


if (testScore >= 90) {
  grade = 'A';
} else if (testScore >= 80) {
  grade = 'B';
} else if (testScore >= 70) {
  grade = 'C';
} else if (testScore >= 60) {
  grade = 'D';
} else {
  grade = 'F';
}


System.out.println("Grade: " + grade); // Prints: C

if Statement

An if statement executes a block of code when a specified boolean expression is evaluated as true.

if (true) {
	System.out.println("This code executes");
}
// Prints: This code executes


if (false) {
	System.out.println("This code does not execute");
}
// There is no output for the above statement

Nested Conditional Statements

A nested conditional statement is a conditional statement nested inside of another conditional statement. The outer conditional statement is evaluated first; if the condition is true, then the nested conditional statement will be evaluated.

boolean studied = true;
boolean wellRested = true;


if (wellRested) {
  System.out.println("Best of luck today!");  
  if (studied) {
    System.out.println("You are prepared for your exam!");
  } else {
    System.out.println("Study before your exam!");
  }
}


// Prints: Best of luck today!
// Prints: You are prepared for your exam!

NOT Operator

The NOT logical operator is represented by !. This operator negates the value of a boolean expression.

boolean a = true;
System.out.println(!a); // Prints: false


System.out.println(!false) // Prints: true

AND Operator

The AND logical operator is represented by &&. This operator returns true if the boolean expressions on both sides of the operator are true; otherwise, it returns false.

System.out.println(true && true); // Prints: true
System.out.println(true && false); // Prints: false
System.out.println(false && true); // Prints: false
System.out.println(false && false); // Prints: false

The OR Operator

The logical OR operator is represented by ||. This operator will return true if at least one of the boolean expressions being compared has a true value; otherwise, it will return false.

System.out.println(true || true); // Prints: true
System.out.println(true || false); // Prints: true
System.out.println(false || true); // Prints: true
System.out.println(false || false); // Prints: false

Conditional Operators - Order of Evaluation

If an expression contains multiple conditional operators, the order of evaluation is as follows: Expressions in parentheses -> NOT -> AND -> OR.

boolean foo = true && (!false || true); // true
/* 
(!false || true) is evaluated first because it is contained within parentheses. 


Then !false is evaluated as true because it uses the NOT operator. 


Next, (true || true) is evaluation as true. 


Finally, true && true is evaluated as true meaning foo is true. */

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    Learn Java

    Learn to code in Java — a robust programming language used to create software, web and mobile apps, and more.
    • Beginner Friendly.
      17 hours
  • Skill path

    Build Basic Android Apps with Java

    By the end of this Skill Path, you will have created your very own fully functional quiz game for Android Devices with Java.
    • Includes 6 Courses
    • With Certificate
    • Beginner Friendly.
      16 hours
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