Loops in Java
Agenda
-
for loops
-
while loops
-
do-while loops
-
break statement
-
continue statement
For loop
Java for loop is used to execute a block a code a certain number of times.
It is recommended to use for loop when the exact number of iterations is known beforehand.
for (initialisation; condition; update) {
// body of the loop
}The syntax of for loop is:
Print numbers from 1 till 10
Print all integers from 1 to 10 i.e. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10
class Main {
public static void main(String[] args) {
}
}Print numbers from 1 till 10
Print all integers from 1 to 10 i.e. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10
class Main {
public static void main(String[] args) {
for (<initialisation>; <condition> ; <update>) {
...
}
}
}Print numbers from 1 till 10
Print all integers from 1 to 10 i.e. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10
class Main {
public static void main(String[] args) {
for (int i = 1; <condition> ; <update>) {
...
}
}
}Print numbers from 1 till 10
Print all integers from 1 to 10 i.e. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10
class Main {
public static void main(String[] args) {
for (int i = 1; <condition> ; i++) {
...
}
}
}Print numbers from 1 till 10
Print all integers from 1 to 10 i.e. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10
class Main {
public static void main(String[] args) {
for (int i = 1; i <= 10 ; i++) {
...
}
}
}Print numbers from 1 till 10
Print all integers from 1 to 10 i.e. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10
class Main {
public static void main(String[] args) {
for (int i = 1; i <= 10; i++) {
System.out.println(i);
}
}
}
Largest of N numbers
Given an integer N i.e. the size of the input, followed by N more integers, find the largest of these N numbers.
Sample Input
5
10 -3 2 12 7
Sample Output
12
Largest of N numbers
Given an integer N i.e. the size of the input, followed by N more integers, find the largest of these N numbers.
Sample Input
5
10 -3 2 12 7
Sample Output
12
class Main {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int n = sc.nextInt();
}
}Largest of N numbers
Given an integer N i.e. the size of the input, followed by N more integers, find the largest of these N numbers.
Sample Input
5
10 -3 2 12 7
Sample Output
12
class Main {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int n = sc.nextInt();
for (int i = 1; i <= n; i++) {
int current = sc.nextInt();
}
}
}Largest of N numbers
Given an integer N i.e. the size of the input, followed by N more integers, find the largest of these N numbers.
Sample Input
5
10 -3 2 12 7
Sample Output
12
class Main {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int n = sc.nextInt();
int maxValue = Integer.MIN_VALUE;
for (int i = 1; i <= n; i++) {
int current = sc.nextInt();
}
System.out.println(maxValue);
}
}Largest of N numbers
Given an integer N i.e. the size of the input, followed by N more integers, find the largest of these N numbers.
Sample Input
5
10 -3 2 12 7
Sample Output
12
class Main {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int n = sc.nextInt();
int maxValue = Integer.MIN_VALUE;
for (int i = 1; i <= n; i++) {
int current = sc.nextInt();
maxValue = Math.max(maxValue, current);
}
System.out.println(maxValue);
}
}The Java while loops is used to execute a specific block of code until a certain condition is met.
The syntax of the while loop is:
While loops
while (condition) {
// body of loop
}Print all integers from 1 to 10 i.e. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10
Print numbers from 1 till 10
class Main {
public static void main(String[] args) {
}
}Print all integers from 1 to 10 i.e. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10
Print numbers from 1 till 10
class Main {
public static void main(String[] args) {
int i = 1; // Initialisation
}
}Print all integers from 1 to 10 i.e. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10
Print numbers from 1 till 10
class Main {
public static void main(String[] args) {
int i = 1; // Initialisation
// Condition
while (i <= 10) {
// Body of the loop
}
}
}Print all integers from 1 to 10 i.e. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10
Print numbers from 1 till 10
class Main {
public static void main(String[] args) {
int i = 1; // Initialisation
// Condition
while (i <= 10) {
System.out.println(i);
}
}
}Print all integers from 1 to 10 i.e. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10
Print numbers from 1 till 10
class Main {
public static void main(String[] args) {
int i = 1; // Initialisation
// Condition
while (i <= 10) {
System.out.println(i);
i++; // Update
}
}
}Count Digits of a Number
Given an integer N, count and print its number of digits
Sample Input
35493
Sample Output
5
Count Digits of a Number
Given an integer N, count and print its number of digits
Sample Input
35493
Sample Output
5
class Main {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int num = sc.nextInt();
}
}Count Digits of a Number
Given an integer N, count and print its number of digits
Sample Input
35493
Sample Output
5
class Main {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int num = sc.nextInt();
int digits = 0;
while (/* condition */) {
// body of loop
}
System.out.println(digits);
}
}Count Digits of a Number
Given an integer N, count and print its number of digits
Sample Input
35493
Sample Output
5
class Main {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int num = sc.nextInt();
int digits = 0;
while (/* condition */) {
num /= 10;
}
System.out.println(digits);
}
}Count Digits of a Number
Given an integer N, count and print its number of digits
Sample Input
35493
Sample Output
5
class Main {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int num = sc.nextInt();
int digits = 0;
while (num > 0) {
num /= 10;
}
System.out.println(digits);
}
}Count Digits of a Number
Given an integer N, count and print its number of digits
Sample Input
35493
Sample Output
5
class Main {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int num = sc.nextInt();
int digits = 0;
while (num > 0) {
num /= 10;
digits++;
}
System.out.println(digits);
}
}The do-while loop is very similar to the while loop. However the body of do-while loop is executed once before the condition is checked.
The syntax of the do while loop is:
do-while loop
do {
// body of loop
} while (condition);Sum of positive numbers
Given a stream of numbers, read the numbers till you read a -ve integer and print their sum of numbers read so far.
Sample Input
5 3 2 -4 2 0 9 ...
Sample Output
6
Sum of positive numbers
class Main {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
}
}
Given a stream of numbers, read the numbers till you read a -ve integer and print their sum of numbers read so far.
Sample Input
5 3 2 -4 2 0 9 ...
Sample Output
6
Sum of positive numbers
Given a stream of numbers, read the numbers till you read a -ve integer and print their sum of numbers read so far.
Sample Input
5 3 2 -4 2 0 9 ...
Sample Output
6
class Main {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int sum = 0;
int num;
}
}
Sum of positive numbers
Given a stream of numbers, read the numbers till you read a -ve integer and print their sum of numbers read so far.
Sample Input
5 3 2 -4 2 0 9 ...
Sample Output
6
class Main {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int sum = 0;
int num;
do {
num = sc.nextInt();
} while (/* condition */);
}
}
Sum of positive numbers
Given a stream of numbers, read the numbers till you read a -ve integer and print their sum of numbers read so far.
Sample Input
5 3 2 -4 2 0 9 ...
Sample Output
6
class Main {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int sum = 0;
int num;
do {
num = sc.nextInt();
} while (num >= 0);
}
}
Sum of positive numbers
Given a stream of numbers, read the numbers till you read a -ve integer and print their sum of numbers read so far.
Sample Input
5 3 2 -4 2 0 9 ...
Sample Output
6
class Main {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int sum = 0;
int num;
do {
num = sc.nextInt();
sum += num;
} while (num >= 0);
}
}
Sum of positive numbers
Given a stream of numbers, read the numbers till you read a -ve integer and print their sum of numbers read so far.
Sample Input
5 3 2 -4 2 0 9 ...
Sample Output
6
class Main {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int sum = 0;
int num;
do {
num = sc.nextInt();
sum += num;
} while (num >= 0);
System.out.println("Sum = " + sum);
}
}
The break statement is used to terminate a loop it is enclosed inside. The program resumes control at the next statement following the loop.
break statement
class Main {
public static void main(String[] args) {
for (int i = 1; i <= 10; i++) {
if (i == 5)
break;
System.out.println(i);
}
System.out.println("After the loop");
}
}
Output:
1
2
3
4
After the loop
The break statement is used to terminate a loop it is enclosed inside. The program resumes control at the next statement following the loop.
break statement
class Main {
public static void main(String[] args) {
int i = 1;
while (i <= 10) {
if (i == 5)
break;
System.out.println(i);
i++;
}
System.out.println("After the loop");
}
}Output:
1
2
3
4
After the loop
The continue statement is used in loop control to skip an iteration. It can be used in all types of loops.
continue statement
class Main {
public static void main(String[] args) {
for (int i = 1; i <= 10; i++) {
if (i % 3 == 0)
continue;
System.out.print(i + " ");
}
}
}This program skips the print statement in every 3rd iteration.
Output:
1 2 4 5 7 8 10
Random Game
Write a program to generate random numbers between [1, 10] and print them to the output.
Terminate when you get 5.
Random Game
Write a program to generate random numbers between [1, 10] and print them to the output.
Terminate when you get 5.
class Main {
public static void main(String[] args) {
while (true) {
int num = (int) (Math.random() * 10 + 1);
System.out.print(num + " ");
}
}
}Random Game
Write a program to generate random numbers between [1, 10] and print them to the output.
Terminate when you get 5.
class Main {
public static void main(String[] args) {
while (true) {
int num = (int) (Math.random() * 10 + 1);
if (num == 5)
break;
System.out.print(num + " ");
}
}
}Random Game
Write a program to generate random numbers between [1, 10] and print them to the output.
Terminate when you get 5.
Skip all multiples of 4.
class Main {
public static void main(String[] args) {
while (true) {
int num = (int) (Math.random() * 10 + 1);
if (num == 5)
break;
System.out.print(num + " ");
}
}
}Random Game
Write a program to generate random numbers between [1, 10] and print them to the output.
Terminate when you get 5.
Skip all multiples of 4.
class Main {
public static void main(String[] args) {
while (true) {
int num = (int) (Math.random() * 10 + 1);
if (num == 5)
break;
if (num % 4 == 0)
continue;
System.out.print(num + " ");
}
}
}