# Print prime numbers from 1 to 100 in Java

In this post, you will learn different ways to print **prime numbers from 1 to 100** using the **Java** programming language.

A **prime number** is a whole number greater than 1 whose only factors are 1 and itself, like -2, 3, 5, 7, 11, etc. For example, 17 is a prime number because it is only divisible by 1 and 17. On the other hand, 18 is not a prime number because it is divisible by 2, 3, 6, 9, and the number itself.

## Java print prime numbers from 1 to 100 using for loop

Here, we have used **for loop** to get prime numbers from 1 to 100. We loop over the number range (1 to 100) and check whether the number is prime or not. The for loop iterates from **i = 0** to **i = given number**. If the remainder of **i/num = 0**, then it increases the count by 1. After all the iterations, if **counter=2**, then that number is a prime number.

```
public class CheckPrimeNumbers
{
public static void main (String[] args)
{
int i =0;
int num =0;
String prime_numbers = "";
for (i = 1; i <= 100; i++)
{
int counter=0;
for(num =i; num>=1; num--)
{
if(i%num==0)
{
counter = counter + 1;
}
}
if (counter ==2)
{
prime_numbers = prime_numbers + i + " ";
}
}
System.out.println("Prime Numbers between 1 and 100 :");
System.out.println(prime_numbers);
}
}
```

**Output of the above code:**

```
Prime Numbers between 1 and 100 :
2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97
```

## Java print prime numbers from 1 to 100 using while loop

Here, we have used the **while loop** to get prime numbers from 1 to 100.

```
public class PrimeNumbers
{
public static void main(String[] args)
{
int counter=0, n=0, i=1, j=1;
while(i<100)
{
j=1;
counter=0;
while(j<=i)
{
if(i%j==0)
counter++;
j++;
}
if(counter==2)
{
System.out.printf("%d ",i);
n++;
}
i++;
}
}
}
```

**Output of the above code:**

`2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97 `

In the above code, we have two while loops. The inner while loop does the testing with each possible divisor. If the inner loop finds a divisor, the number is not prime, so it breaks out without printing anything. If counter = 2, then we can assume that the number is prime. The outer loop works through all the numbers between 1 and 100. This loop is broken when we have reached the breaking point of numbers to test.

## Java print prime numbers from 1 to 100 using method

Here, we ask the user to provide the minimum and maximum values, and we separate the logic of the prime numbers and place it in a separate method.

```
import java.util.Scanner;
public class PrimeNumbers {
private static Scanner sc;
public static void main(String[] args)
{
int num, min, max, i, count;
sc = new Scanner(System.in);
System.out.print("Please enter the minimum value: ");
min = sc.nextInt();
System.out.print("Please enter the maximum value: ");
max = sc.nextInt();
System.out.println("Prime numbers from 1 to 100 are: ");
for(num = min; num <= max; num++)
{
count = 0;
for (i = 2; i <= num/2; i++)
{
if(num % i == 0)
{
count++;
break;
}
}
if(count == 0 && num != 1 )
{
System.out.print(num + " ");
}
}
}
}
```

**Output of the above code:**

```
Please enter the minimum value: 1
Please enter the maximum value: 100
Prime numbers from 1 to 100 are:
2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97
```

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