javaistic · arghyaxcodes · Oct 19, 2022 · Oct 19, 2022 · Oct 19, 2022
diff --git a/src/navs/documentation.js b/src/navs/documentation.js
@@ -23,5 +23,6 @@ export const documentationNav = {
     pages['switch-statement'],
     pages['for-loop'],
     pages['enhanced-for-loop'],
+    pages['while-and-do-while-loop'],
   ],
 }
diff --git a/src/pages/docs/while-and-do-while-loop.mdx b/src/pages/docs/while-and-do-while-loop.mdx
@@ -0,0 +1,298 @@
+---
+title: Java while & do...while loop
+description: In this tutorial, we will learn how to use while and do while loop in Java with the help of examples.
+---
+
+In computer programming, loops are used to repeat a block of code. For example, if you want to show a message 100 times, then you can use a loop. It's just a simple example; you can achieve much more with loops.
+
+In the previous tutorial, you learned about [Java for loop](./for-loop). Here, you are going to learn about `while` and `do...while` loops.
+
+import { List, ListItemGood } from '@/components/List'
+import { TipInfo } from '@/components/Tip'
+
+
+## Java while loop
+
+Java while loop is used to run a specific code until a certain condition is met. The syntax of the while loop is:
+
+```java
+while (testExpression) {
+    // body of loop
+}
+```
+Here,
+
+1. A `while` loop evaluates the **textExpression** inside the parenthesis `()`.
+2. If the **textExpression** evaluates to `true`, the code inside the `while` loop is executed.
+3. The **textExpression** is evaluated again.
+4. This process continues until the **textExpression** is `false`.
+5. When the **textExpression** evaluates to `false`, the loop stops.
+
+To learn more about the conditions, visit [Java relational](./operators#3-java-relational-operators) and [logical operators](./operators#4-java-logical-operators).
+
+---
+
+## Flowchart of while loop
+![Flowchart of Java while loop](https://via.placeholder.com/600x400?text=Flowchart+of+Java+while+loop)
+
+---
+
+### Example 1: Display Numbers from 1 to 5
+
+```java
+// Program to display numbers from 1 to 5
+
+class Main {
+  public static void main(String[] args) {
+
+    // declare variables
+    int i = 1, n = 5;
+
+    // while loop from 1 to 5
+    while(i <= n) {
+      System.out.println(i);
+      i++;
+    }
+  }
+}
+```
+
+
+#### Output
+
+```text
+1
+2
+3
+4
+5
+```
+
+Here is how this program works.
+
+| Iteration | Variable          | Condition: i <= n | Action                                     |
+|-----------|-------------------|-------------------|--------------------------------------------|
+| 1st       | `i = 1` `n = 5`   | `true`            | `1` is printed. `i` is increased to **2**. |
+| 2nd       | `i = 2` `n = 5 `  | `true`            | `2` is printed. `i` is increased to **3**. |
+| 3rd       | `i = 3` ` n = 5 ` | `true`            | `3` is printed.`i` is increased to **4**.  |
+| 4th       | `i = 4` ` n = 5 ` | `true`            | `4` is printed. `i` is increased to **5**. |
+| 5th       | `i = 5` ` n = 5`  | `true`            | `5` is printed. `i` is increased to **6**. |
+| 6th       | `i = 6` `n = 5`   | `false`           | The loop is terminated                     |
+
+### Example 2: Sum of Positive Numbers Only
+
+```java
+// Java program to find the sum of positive numbers
+import java.util.Scanner;
+
+class Main {
+  public static void main(String[] args) {
+
+    int sum = 0;
+
+    // create an object of Scanner class
+    Scanner input = new Scanner(System.in);
+
+    // take integer input from the user
+    System.out.println("Enter a number");
+    int number = input.nextInt();
+
+    // while loop continues
+    // until entered number is positive
+    while (number >= 0) {
+      // add only positive numbers
+      sum += number;
+
+      System.out.println("Enter a number");
+      number = input.nextInt();
+    }
+
+    System.out.println("Sum = " + sum);
+    input.close();
+  }
+}
+```
+
+#### Output
+
+```text
+Enter a number
+25
+Enter a number
+9
+Enter a number
+5
+Enter a number
+-3
+Sum = 39
+```
+
+In the above program, we have used the [Scanner class](./scanner) to take input from the user. Here, `nextInt()` takes integer input from the user.
+
+The `while` loop continues until the user enters a negative number. During each iteration, the number entered by the user is added to the `sum` variable.
+
+When the user enters a negative number, the loop terminates. Finally, the total sum is displayed.
+
+## Java do...while loop
+
+The `do...while` loop is similar to while loop. However, the body of `do...while` loop is executed once before the test expression is checked. For example,
+```java
+do {
+    // body of loop
+} while(textExpression);
+```
+Here,
+
+1. The body of the loop is executed at first. Then the **textExpression** is evaluated.
+2. If the **textExpression** evaluates to `true`, the body of the loop inside the `do` statement is executed again.
+3. The **textExpression** is evaluated once again.
+4. If the **textExpression** evaluates to `true`, the body of the loop inside the `do` statement is executed again.
+5. This process continues until the **textExpression** evaluates to false. Then the loop stops.
+
+## Flowchart of do...while loop
+![Flowchart of Java do...while loop](https://via.placeholder.com/600x400?text=Flowchart+of+Java+do...while+loop)
+
+Let's see the working of `do...while` loop.
+
+---
+
+### Example 3: Display Numbers from 1 to 5
+
+```java
+// Java Program to display numbers from 1 to 5
+
+import java.util.Scanner;
+
+// Program to find the sum of natural numbers from 1 to 100.
+
+class Main {
+  public static void main(String[] args) {
+
+    int i = 1, n = 5;
+
+    // do...while loop from 1 to 5
+    do {
+      System.out.println(i);
+      i++;
+    } while(i <= n);
+  }
+}
+```
+#### Output
+
+```text
+1
+2
+3
+4
+5
+```
+
+Here is how this program works.
+
+| Iteration | Variable          | Condition: i <= n | Action                                     |
+|-----------|-------------------|-------------------|--------------------------------------------|
+|           | `i = 1` `n = 5`   | not checked       | `1` is printed. `i` is increased to **2**. |
+| 1st       | `i = 2` `n = 5 `  | `true`            | `2` is printed. `i` is increased to **3**. |
+| 2nd       | `i = 3` ` n = 5 ` | `true`            | `3` is printed.`i` is increased to **4**.  |
+| 3rd       | `i = 4` ` n = 5 ` | `true`            | `4` is printed. `i` is increased to **5**. |
+| 4th       | `i = 5` ` n = 5`  | `true`            | `5` is printed. `i` is increased to **6**. |
+| 5th       | `i = 6` `n = 5`   | `false`           | The loop is terminated                     |
+
+---
+
+### Example 4: Sum of Positive Numbers
+
+```java
+// Java program to find the sum of positive numbers
+import java.util.Scanner;
+
+class Main {
+  public static void main(String[] args) {
+
+    int sum = 0;
+    int number = 0;
+
+    // create an object of Scanner class
+    Scanner input = new Scanner(System.in);
+
+    // do...while loop continues
+    // until entered number is positive
+    do {
+      // add only positive numbers
+      sum += number;
+      System.out.println("Enter a number");
+      number = input.nextInt();
+    } while(number >= 0);
+
+    System.out.println("Sum = " + sum);
+    input.close();
+  }
+}
+```
+#### Output 1
+
+```text
+Enter a number
+25
+Enter a number
+9
+Enter a number
+5
+Enter a number
+-3
+Sum = 39
+```
+Here, the user enters a positive number, that number is added to the `sum` variable. And this process continues until the number is negative. When the number is negative, the loop terminates and displays the sum without adding the negative number.
+
+#### Output 2
+
+```text
+Enter a number
+-8
+Sum is 0
+```
+Here, the user enters a negative number. The test condition will be `false` but the code inside of the loop executes once.
+
+## Infinite while loop
+
+If **the condition** of a loop is always `true`, the loop runs for infinite times (until the memory is full). For example,
+
+```java
+// infinite while loop
+while(true){
+    // body of loop
+}
+```
+## Infinite do...while loop
+
+Here is an example of an infinite `do...while` loop.
+
+```java
+// infinite do...while loop
+int count = 1;
+do {
+   // body of loop
+} while(count == 1)
+```
+In the above programs, the **textExpression** is always `true`. Hence, the loop body will run for infinite times.
+
+---
+
+## for and while loops
+
+The `for` loop is used when the number of iterations is known. For example,
+
+```java
+for (let i = 1; i <=5; ++i) {
+   // body of loop
+}
+```
+
+And `while` and `do...while` loops are generally used when the number of iterations is unknown. For example,
+
+```java
+while (condition) {
+    // body of loop
+}
+```