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JAVA Programming
What are control statements in Java and what are they used for?
Control statements in Java are statements that control the flow of execution in a program based on certain conditions or loops. They allow programmers to specify which statements should be executed under certain conditions, or to execute a set of statements repeatedly based on certain conditions.
Some of the commonly used control statements in Java include:
ifstatement: It is used to execute a block of code if a certain condition is true.if-elsestatement: It is used to execute a block of code if a condition is true, and a different block of code if the condition is false.switchstatement: It is used to execute different blocks of code based on the value of an expression.forloop: It is used to execute a set of statements repeatedly for a specified number of times.whileloop: It is used to execute a set of statements repeatedly as long as a certain condition is true.do-whileloop: It is used to execute a set of statements repeatedly at least once, and then as long as a certain condition is true.breakstatement: It is used to terminate the execution of a loop or a switch statement.continuestatement: It is used to skip the current iteration of a loop and move on to the next iteration.
Control statements are an essential part of any programming language, as they allow programmers to create more complex and dynamic programs that can make decisions and repeat tasks based on certain conditions.
Explain the different types of control statements in Java and give examples of each type?
Sure, here are the different types of control statements in Java along with examples of each type:
ifstatement: This control statement is used to execute a block of code only if a certain condition is true.
Example:
int x = 5;
if (x < 10) {
System.out.println("x is less than 10");
}
if-elsestatement: This control statement is used to execute one block of code if a condition is true, and a different block of code if the condition is false.
Example:
int x = 5;
if (x < 10) {
System.out.println("x is less than 10");
} else {
System.out.println("x is greater than or equal to 10");
}
switchstatement: This control statement is used to execute different blocks of code based on the value of an expression.
Example:
int dayOfWeek = 2;
switch (dayOfWeek) {
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("Invalid day of week");
}
forloop: This control statement is used to execute a set of statements repeatedly for a specified number of times.
Example:
for (int i = 0; i < 10; i++) {
System.out.println(i);
}
whileloop: This control statement is used to execute a set of statements repeatedly as long as a certain condition is true.
Example:
int i = 0;
while (i < 10) {
System.out.println(i);
i++;
}
do-whileloop: This control statement is used to execute a set of statements repeatedly at least once, and then as long as a certain condition is true.
Example:
int i = 0;
do {
System.out.println(i);
i++;
} while (i < 10);
breakstatement: This control statement is used to terminate the execution of a loop or a switch statement.
Example:
for (int i = 0; i < 10; i++) {
if (i == 5) {
break;
}
System.out.println(i);
}
continuestatement: This control statement is used to skip the current iteration of a loop and move on to the next iteration.
Example:
for (int i = 0; i < 10; i++) {
if (i == 5) {
continue;
}
System.out.println(i);
}
What is the syntax for an if-else statement in Java and how does it work?
The syntax for an if-else statement in Java is as follows:
if (condition) {
// code to be executed if condition is true
} else {
// code to be executed if condition is false
}
In this syntax, the if keyword is used to begin the statement, followed by the condition to be evaluated in parentheses. If the condition is true, the code within the first set of curly braces will be executed. If the condition is false, the code within the second set of curly braces (the else block) will be executed instead.
Here is an example:
int age = 18;
if (age >= 18) {
System.out.println("You are old enough to vote.");
} else {
System.out.println("You are not yet old enough to vote.");
}
In this example, the condition age >= 18 is evaluated. Since the value of age is 18, which is greater than or equal to 18, the code within the first set of curly braces is executed, and the output “You are old enough to vote.” is printed to the console.
Give an example of using a switch statement in Java?
Certainly! Here’s an example of using a switch statement in Java:
int dayOfWeek = 3;
String dayName;
switch (dayOfWeek) {
case 1:
dayName = "Monday";
break;
case 2:
dayName = "Tuesday";
break;
case 3:
dayName = "Wednesday";
break;
case 4:
dayName = "Thursday";
break;
case 5:
dayName = "Friday";
break;
case 6:
dayName = "Saturday";
break;
case 7:
dayName = "Sunday";
break;
default:
dayName = "Invalid day";
break;
}
System.out.println("Today is " + dayName);
In this example, the switch statement evaluates the value of the dayOfWeek variable. Depending on the value, the code within the corresponding case block will be executed. The break statement is used to prevent execution from falling through to the next case block.
If the value of dayOfWeek does not match any of the case values, the code within the default block will be executed. In this example, if dayOfWeek had a value other than 1 through 7, the value of dayName would be set to “Invalid day”.
In the end, the program prints the value of dayName, which is set based on the value of dayOfWeek. In this example, the output would be “Today is Wednesday”.
Questions on Chapter 6