Control flow statements
The control flow statements are the statements that have capabilities to take control in the hand of program execution. Each statement inside our program is generally executed from top to bottom, in the same order they are written.
There are three categories of control statements
- Decision-Making statements (if-then, if-then-else, switch)
- Looping statements (for, while, do-while)
- Branching statements (break, continue, return)
Java If Statement with Example
It is the most basic and mostly used statement in our program statement. The if statement conditionally executes a single statement or block of code.
Syntax
if (boolean expression){
// this block will be executed if the
// boolean expression is evaluated to true;
statement…
}
If the Boolean statement is evaluated to true, the code written inside if statement will be executed. If the expression is evaluated to false then block will not be executed and it continues with program execution.
The below program checks whether an inputted number is even.
public class mydemo {
public static void main(String[] args) {
int n = 10;
if (n % 2 == 0) { // check reminder of number
System.out.println(n + " is Even Number");
}
}
}
Explanation:
Here in this example, 10 (even number). So it will print “10 is EVEN number” on the console.
Java if-else statement with Example
An if statement can be followed by an optional else statement. Else statements execute if a Boolean expression inside if evaluated to false.
Syntax
if(condition){
//code if condition is true
}else{
//code if condition is false
}
An if statement can have an else statement, here in the example –
Below the program check whether the inputted number is even or odd. If the number is even it will print Even number and Else the number is odd it will print Odd number.
public class mydemo {
public static void main(String[] args) {
int n = 35;
if (n % 2 == 0) { // check reminder of number
System.out.println(n + " is Even Number");
}
else
{
System.out.println(n + " is Odd Number");
}
}
}
Java if-else-if ladder Statement with Example
There is another way of putting else if together when multiple decisions are involved. A multipath decision is a chain of if in which the statement associated with each else is an if.
This construct is known as the else if ladder.
Syntax
if(condition1){
//code to be executed if condition1 is true
}else if(condition2){
//code to be executed if condition2 is true
}
else if(condition3){
//code to be executed if condition3 is true
}
...
else{
//code to be executed if all the conditions are false
}
public class mytest {
public static void main(String[] args) {
int marks = 20;
if (marks >= 70) { // if statement
System.out.println("Grade A");
}
else if (marks >= 30) { // else if statement
System.out.println("Grade B");
}
else if (marks >= 90) { // if statement
System.out.println("Grade C");
}
else { // else statement
System.out.println("Grade D");
}
}
}
Java Nested If statements with Example
When a series of decisions are involved, we may have to use more than one if…else statement in nested form as follows:
The logic in execution is that, if the test condition-1 is evaluated to false, the test statement-3 will be executed. Otherwise, it continues to perform the second test.
Here below program employs nested if…else statements to determine the largest of given three numbers.
Syntax
if(condition){
//code to be executed
if(condition){
//code to be executed
}
}
public class mytest {
public static void main(String[] args) {
int a = 155, b = 400, c = 1000;
System.out.println("Largest Value is :");
if (a > b) {
if (a > c) {
System.out.println(a);
} else {
System.out.println(c);
}
} else {
if (c > b) {
System.out.println(c);
} else {
System.out.println(b);
}
}
}
}