Java control statements are an integral part of any Java program as they help regulate the execution flow. These statements allow developers to make decisions, create loops, and modify the sequence of program execution.

Java Control Statements

Types of Control Statements

Selection Statements
Iteration Statements
Jump Statements

1.Selection Statements

Selection statements are an important part of programming languages.

Java offers two types of selection statements:

if-else statements
switch statements

These statements allow developers to make decisions based on certain conditions and control the flow of execution in their programs.

1.1. if-else statements

If-else statements are an important part of Java programming that allows developers to make decisions based on specific conditions. The if-else statement executes a block of code if a particular condition is true, and another block of code if the condition is false.

Syntax for the if-else statement

if (condition) { 
// code to execute if the condition is true 
} else { 
// code to execute if the condition is false 
}

Here, the condition is a Boolean expression that evaluates to true or false. If the condition is true, the code inside the if-block is executed, and if the condition is false, the code inside the else-block is executed.

Example 1.

int num = 10; 
if (num > 0) { 
 System.out.println("Number is positive"); 
} else { 
 System.out.println("Number is not positive"); 
}

In the above example, we have declared a variable num with the value 10. We then use an if-else statement to check whether num is positive or not. The condition in this case is num > 0. Since the value of num is greater than 0, the code inside the if-block is executed, which prints the message "Number is positive" to the console.

Example 2.

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

In the above example, we have declared a variable num with the value -5. We use an if-else statement to check whether num is positive or not. Since the value of num is less than 0, the code inside the else-block is executed, which prints the message "Number is not positive" to the console.

if-else statements are a crucial part of Java programming, enabling developers to execute different blocks of code based on specific conditions. The syntax is straightforward and easy to understand, making it a fundamental concept for beginners to grasp. By mastering if-else statements, developers can build more complex programs that involve more intricate decision-making.

1.2.Switch statements

Switch statements are another type of control statement in Java that allows developers to execute different blocks of code based on the value of an expression. It provides a more concise way of writing multiple if-else statements.

Syntax for a switch statement


switch (expression) { 
case value1: 
// code to execute if expression == value1 
break; 
case value2: 
// code to execute if expression == value2 
break; 
 ... 
default: 
// code to execute if none of the above cases are true 
}

Here, the expression is a variable or expression that is evaluated. The switch statement then checks if the value of the expression matches any of the values specified in the case statements. If a match is found, the code inside that case statement is executed, and the break statement is used to exit the switch statement. If no match is found, the code inside the default block is executed.

Example 1.


int dayOfWeek = 3; 
switch (dayOfWeek) { 
case 1: 
 System.out.println("Monday"); 
break;
    case 2: 
 System.out.println("Tuesday"); 
break; 
case 3: 
 System.out.println("Wednesday"); 
break; 
case 4: 
 System.out.println("Thursday"); 
break; 
case 5: 
 System.out.println("Friday"); 
break; 
default: 
 System.out.println("Invalid day"); 
}

In the above example, we have declared a variable dayOfWeek with the value 3. We use a switch statement to print the day of the week based on the value of dayOfWeek. Since the value of dayOfWeek is 3, the code inside the case statement for 3 is executed, which prints "Wednesday" to the console.

Example 2.

int dayOfWeek = 7; 
switch (dayOfWeek) { 
case 1: 
 System.out.println("Monday"); 
break; 
case 2: 
 System.out.println("Tuesday"); 
break; 
case 3: 
 System.out.println("Wednesday"); 
break; 
case 4: 
 System.out.println("Thursday"); 
break; 
case 5: 
 System.out.println("Friday"); 
break; 
default: 
 System.out.println("Invalid day"); 
}

In the above example, we have declared a variable dayOfWeek with the value 7. We use a switch statement to print the day of the week based on the value of dayOfWeek. Since the value of dayOfWeek does not match any of the case statements, the code inside the default block is executed, which prints "Invalid day" to the console.

switch statements provide a more concise way of writing multiple if-else statements in Java. By using switch statements, developers can execute different blocks of code based on the value of an expression. The syntax is straightforward and easy to understand, making it a fundamental concept for beginners to grasp. By mastering switch statements, developers can build more complex programs that involve more intricate decision-making.

2.Iteration Statements

Iteration statements, also known as loops, are control structures in Java that allow developers to execute a block of code repeatedly until a specific condition is met.

Types of Iteration Statements

for-each loop
while
do-while loop
for loop

2.1. for-each loop

The for-each loop is a type of for loop introduced in Java 5 that simplifies iteration over arrays and collections. It is also known as the enhanced for loop or the for-in loop.
Syntax of the for-each loop.

Syntax of the for-each loop


for (elementType element : array/collection) { 
// code to execute 
}

Here, elementType is the data type of the elements in the array/collection, element is a variable that represents each element in the array/collection, and array/collection is the array or collection that we want to iterate over.

Example of the for-each loop

Let's take an example to understand how the for-each loop works in Java


int[] numbers = {1, 2, 3, 4, 5}; 
for (int num : numbers) { 
 System.out.println(num); 
}

In the above example, we use the for-each loop to iterate over the numbers array and print each element. The elementType is int, the element variable is num, and the array is numbers.

Output:

Advantages of the for-each loop

Simplicity: The for-each loop simplifies the code for iterating over arrays and collections.
Safety: The for-each loop eliminates the possibility of index-out-of-bounds errors and makes the code safer.
Readability: The for-each loop makes the code more readable and easier to understand.
Performance: The for-each loop is generally faster than the traditional for loop for iterating over arrays and collections.

The for-each loop is a powerful construct in Java that simplifies iteration over arrays and collections. By using the for-each loop, developers can write cleaner, safer, and more readable code.

2.2. while loop

In Java, the while loop is a control statement that allows code to be executed repeatedly based on a boolean condition. The while loop will continue executing the code as long as the condition remains true. In this article, we will explore how to use the while loop in Java with an example.

Syntax of the while loop


while (condition) {
    // code to execute
}

Here, condition is a boolean expression that is evaluated before each iteration of the loop. If the condition is true, the code inside the loop will execute. If the condition is false, the loop will terminate.

Example of the while loop

int i = 1; 
while (i <= 5) { 
 System.out.println(i); 
 i++; 
}

In the above example, we use the while loop to print the numbers 1 through 5. The condition is i <= 5, which is true for the first five iterations of the loop. Inside the loop, we print the value of i and then increment it by 1 using the i++ operator.

Output:

Advantages of the while loop

Flexibility: The while loop is very flexible and can be used in a variety of situations.
Simplicity: The while loop is simple and easy to understand, making it a good choice for many programming tasks.
Efficiency: The while loop is very efficient and can be used to process large amounts of data quickly.

The while loop is a powerful construct in Java that allows code to be executed repeatedly based on a boolean condition. By using the while loop, developers can write flexible, simple, and efficient code.

2.3. do-while loop

The do-while loop is a control statement that allows code to be executed repeatedly based on a boolean condition. The do-while loop is similar to the while loop, but the code inside the loop is executed at least once before the condition is checked. In this article, we will explore how to use the do-while loop in Java with an example.

Syntax of the do-while loop


do {
    // code to execute
} 
while (condition);

Here, condition is a boolean expression that is evaluated after each iteration of the loop. If the condition is true, the code inside the loop will execute again. If the condition is false, the loop will terminate.

Example of the do-while loop

int i = 1; 
do { 
 System.out.println(i); 
 i++; 
} 
while (i <= 5);

In the above example, we use the do-while loop to print the numbers 1 through 5. The code inside the loop is executed at least once, regardless of the value of i. Then, the condition is checked. If the condition is true, the code inside the loop will execute again. Inside the loop, we print the value of i and then increment it by 1 using the i++ operator.

Output:

Advantages of the do-while loop

Flexibility: The do-while loop is very flexible and can be used in a variety of situations.
Simplicity: The do-while loop is simple and easy to understand, making it a good choice for many programming tasks.
Efficiency: The do-while loop is very efficient and can be used to process large amounts of data quickly.

the do-while loop is a powerful construct in Java that allows code to be executed repeatedly based on a boolean condition. By using the do-while loop, developers can write flexible, simple, and efficient code.

2.4. for loop

In Java, the for loop is a control statement that allows code to be executed repeatedly based on a specified condition. The for loop is typically used when the number of iterations is known in advance. In this article, we will explore how to use the for loop in Java with an example.

Syntax of the for loop


for (initialization; condition; increment/decrement) { 
// code to execute 
}

Here, initialization is an expression that is executed once before the loop starts. condition is a boolean expression that is evaluated before each iteration of the loop. If the condition is true, the code inside the loop will execute. If the condition is false, the loop will terminate. increment/decrement is an expression that is executed at the end of each iteration of the loop.

Example of the for loop

for (int i = 1; i <= 5; i++) { 
 System.out.println(i); 
}

In the above example, we use the for loop to print the numbers 1 through 5. The initialization expression creates a variable i and sets its initial value to 1. The condition expression checks whether i is less than or equal to 5. Inside the loop, we print the value of i using System.out.println(i). The increment/decrement expression increments i by 1 at the end of each iteration using the i++ operator.

Output:

Advantages of the for loop

Flexibility: The for loop is very flexible and can be used in a variety of situations.
Simplicity: The for loop is simple and easy to understand, making it a good choice for many programming tasks.
Efficiency: The for loop is very efficient and can be used to process large amounts of data quickly.

the for loop is a powerful construct in Java that allows code to be executed repeatedly based on a specified condition. By using the for loop, developers can write flexible, simple, and efficient code.

3.Jump Statements

Jump Statements are control statements that allow the program to transfer control from one part of the program to another.

Types of Jump Statements in Java

break
continue

3.1. Break

The break statement is used to exit a loop or a switch statement. When a break statement is encountered inside a loop, the loop is terminated, and program control is transferred to the next statement after the loop. Similarly, when a break statement is encountered inside a switch statement, the switch statement is terminated, and program control is transferred to the next statement after the switch.

Syntax of the Break


 break;

Example 1:


for (int i = 0; i < 10; i++) { 
if (i == 5) { 
break; 
 } 
 System.out.println(i); 
}

In this example, the for loop will iterate from 0 to 9, but when i becomes equal to 5, the break statement is encountered, and the loop is terminated.

Output

Example 2:

int i = 0; 
while (i < 10) {
if (i == 5) { 
break; 
 } 
 System.out.println(i); 
 i++; 
}

In this example, the while loop will iterate from 0 to 9, but when i becomes equal to 5, the break statement is encountered, and the loop is terminated.

Output

the break statement is a powerful tool for controlling the flow of a Java program. It can be used to terminate a loop or a switch statement and can even be used to exit from a nested loop.

3.2. Continue

The continue statement is used to skip the current iteration of a loop and move to the next iteration. When a continue statement is encountered inside a loop, the loop skips the remaining statements in the current iteration and moves on to the next iteration.

Syntax of the Continue :


 continue;

Example 1 :


for (int i = 0; i < 10; i++) {
if (i == 5) { 
continue; 
 } 
 System.out.println(i); 
}

In this example, the for loop will iterate from 0 to 9, but when i becomes equal to 5, the continue statement is encountered, and the remaining statements in that iteration are skipped.

Output :

The continue statement is often used in combination with an if statement to skip a certain iteration when a certain condition is met.

Example 2 :

int i = 0; 
while (i < 10) { 
 i++; 
if (i % 2 == 0) { 
continue; 
 } 
 System.out.println(i); 
}

In this example, the while loop will iterate from 1 to 10, but when i is an even number, the continue statement is encountered, and the remaining statements in that iteration are skipped. Therefore, the output of the above code will be:

Conclusion

Control Statements in Java are crucial for controlling the flow of execution of a program. Java provides several types of control statements, including selection statements, iteration statements, and jump statements. As a Java programmer, it is essential to understand how to use each type of control statement effectively to create efficient and effective programs.

You Know?

1. What are the control statements in Java?

There are three types of control statements: selection statements, iteration statements, and jump statements.

2. What is the control statement?

Control Statements means controlling the flow of execution of a program. Control statements are used to make decisions, perform loops, and alter the sequence of execution of a program.

3. What is flow control in Java?

Flow control refers to the ability of a program to control the order in which statements are executed. Flow control statements are used to determine the order in which statements are executed based on specific conditions or loops.

4. Is break a control statement?

Yes, break is a control statement in Java. The break statement is used to terminate a loop, switch statement, or labeled block. When executed, the break statement causes the program to immediately exit the enclosing loop, switch statement, or labeled block and resume execution at the next statement after the loop, switch statement, or labeled block.

5. What is a looping statement?

a Looping Statement is a type of control statement that allows a program to execute a block of code repeatedly based on a certain condition. The condition is evaluated before each iteration of the loop, and the loop continues to execute until the condition evaluates to false.

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