How can I make my code more efficient on reading prime number, and continue on looping when 0 or 1 is input











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import java.util.*;


public class PrimeNumber {
private static ArrayList<Integer> listOfPrime = new ArrayList<Integer>();

public static void main(String args) {
Scanner userInput = new Scanner(System.in);
System.out.print("Please enter a number to checked the list of prime number > ");
//Request user to input number.
String input = userInput.nextLine();
int number = 0;
boolean check = false;
//Check if integer entered is it integer
while(check != true) {
try {
// if input can be parse into integer, shows that its number so can change check into true to exit the while loop


number = Integer.parseInt(input);
check = true;
}
catch(NumberFormatException e) {
System.out.println("Please enter numbers only > ");
input = userInput.nextLine();
}
}

//Check if input enter is 0 or 1, as prime number cannot be those.
if(number < 2) {
System.out.println("Prime number cannot be 0 or 1");
}else {
checkPrime(number);
}


}


//Check for all prime numbers within the number user input.
private static void checkPrime(int input) {
boolean primeValidation = true;
//first for loop to check from small to biggest integer in the input
for(int i = 1; i <= input;i++) {
if(i !=1) {

//Second for loop to check from prime number in the small to big number.



//If the number i is 2 or 3, the loop will exit and add into the list as the default is prime, and no option changes it to not prime number.



for(int x = 2; x < i ; x++) {
if(i%x == 0) {
//If the number is divisable by any number to 0, set it to not prime.
primeValidation = false;
}
}
}

`//if the input is either 0 or 1 set it to false and 0 and 1 is not prime


`else {
primeValidation = false;
}
if(primeValidation == true) {
listOfPrime.add(i);
}else {
primeValidation = true;
}


}

System.out.println("The list of prime numbers of the number " + input + " are "+listOfPrime);


}

}









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New contributor




Hau Jia Hung is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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  • Welcome to Code Review. Please fix your indentation. The easiest way to post core is to paste it into the question editor, highlight it, and press Ctrl-K to mark it as a code block. Also tell us what the code accomplishes — see How to Ask.
    – 200_success
    39 mins ago















up vote
0
down vote

favorite












import java.util.*;


public class PrimeNumber {
private static ArrayList<Integer> listOfPrime = new ArrayList<Integer>();

public static void main(String args) {
Scanner userInput = new Scanner(System.in);
System.out.print("Please enter a number to checked the list of prime number > ");
//Request user to input number.
String input = userInput.nextLine();
int number = 0;
boolean check = false;
//Check if integer entered is it integer
while(check != true) {
try {
// if input can be parse into integer, shows that its number so can change check into true to exit the while loop


number = Integer.parseInt(input);
check = true;
}
catch(NumberFormatException e) {
System.out.println("Please enter numbers only > ");
input = userInput.nextLine();
}
}

//Check if input enter is 0 or 1, as prime number cannot be those.
if(number < 2) {
System.out.println("Prime number cannot be 0 or 1");
}else {
checkPrime(number);
}


}


//Check for all prime numbers within the number user input.
private static void checkPrime(int input) {
boolean primeValidation = true;
//first for loop to check from small to biggest integer in the input
for(int i = 1; i <= input;i++) {
if(i !=1) {

//Second for loop to check from prime number in the small to big number.



//If the number i is 2 or 3, the loop will exit and add into the list as the default is prime, and no option changes it to not prime number.



for(int x = 2; x < i ; x++) {
if(i%x == 0) {
//If the number is divisable by any number to 0, set it to not prime.
primeValidation = false;
}
}
}

`//if the input is either 0 or 1 set it to false and 0 and 1 is not prime


`else {
primeValidation = false;
}
if(primeValidation == true) {
listOfPrime.add(i);
}else {
primeValidation = true;
}


}

System.out.println("The list of prime numbers of the number " + input + " are "+listOfPrime);


}

}









share|improve this question









New contributor




Hau Jia Hung is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.




















  • Welcome to Code Review. Please fix your indentation. The easiest way to post core is to paste it into the question editor, highlight it, and press Ctrl-K to mark it as a code block. Also tell us what the code accomplishes — see How to Ask.
    – 200_success
    39 mins ago













up vote
0
down vote

favorite









up vote
0
down vote

favorite











import java.util.*;


public class PrimeNumber {
private static ArrayList<Integer> listOfPrime = new ArrayList<Integer>();

public static void main(String args) {
Scanner userInput = new Scanner(System.in);
System.out.print("Please enter a number to checked the list of prime number > ");
//Request user to input number.
String input = userInput.nextLine();
int number = 0;
boolean check = false;
//Check if integer entered is it integer
while(check != true) {
try {
// if input can be parse into integer, shows that its number so can change check into true to exit the while loop


number = Integer.parseInt(input);
check = true;
}
catch(NumberFormatException e) {
System.out.println("Please enter numbers only > ");
input = userInput.nextLine();
}
}

//Check if input enter is 0 or 1, as prime number cannot be those.
if(number < 2) {
System.out.println("Prime number cannot be 0 or 1");
}else {
checkPrime(number);
}


}


//Check for all prime numbers within the number user input.
private static void checkPrime(int input) {
boolean primeValidation = true;
//first for loop to check from small to biggest integer in the input
for(int i = 1; i <= input;i++) {
if(i !=1) {

//Second for loop to check from prime number in the small to big number.



//If the number i is 2 or 3, the loop will exit and add into the list as the default is prime, and no option changes it to not prime number.



for(int x = 2; x < i ; x++) {
if(i%x == 0) {
//If the number is divisable by any number to 0, set it to not prime.
primeValidation = false;
}
}
}

`//if the input is either 0 or 1 set it to false and 0 and 1 is not prime


`else {
primeValidation = false;
}
if(primeValidation == true) {
listOfPrime.add(i);
}else {
primeValidation = true;
}


}

System.out.println("The list of prime numbers of the number " + input + " are "+listOfPrime);


}

}









share|improve this question









New contributor




Hau Jia Hung is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.











import java.util.*;


public class PrimeNumber {
private static ArrayList<Integer> listOfPrime = new ArrayList<Integer>();

public static void main(String args) {
Scanner userInput = new Scanner(System.in);
System.out.print("Please enter a number to checked the list of prime number > ");
//Request user to input number.
String input = userInput.nextLine();
int number = 0;
boolean check = false;
//Check if integer entered is it integer
while(check != true) {
try {
// if input can be parse into integer, shows that its number so can change check into true to exit the while loop


number = Integer.parseInt(input);
check = true;
}
catch(NumberFormatException e) {
System.out.println("Please enter numbers only > ");
input = userInput.nextLine();
}
}

//Check if input enter is 0 or 1, as prime number cannot be those.
if(number < 2) {
System.out.println("Prime number cannot be 0 or 1");
}else {
checkPrime(number);
}


}


//Check for all prime numbers within the number user input.
private static void checkPrime(int input) {
boolean primeValidation = true;
//first for loop to check from small to biggest integer in the input
for(int i = 1; i <= input;i++) {
if(i !=1) {

//Second for loop to check from prime number in the small to big number.



//If the number i is 2 or 3, the loop will exit and add into the list as the default is prime, and no option changes it to not prime number.



for(int x = 2; x < i ; x++) {
if(i%x == 0) {
//If the number is divisable by any number to 0, set it to not prime.
primeValidation = false;
}
}
}

`//if the input is either 0 or 1 set it to false and 0 and 1 is not prime


`else {
primeValidation = false;
}
if(primeValidation == true) {
listOfPrime.add(i);
}else {
primeValidation = true;
}


}

System.out.println("The list of prime numbers of the number " + input + " are "+listOfPrime);


}

}






java






share|improve this question









New contributor




Hau Jia Hung is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.











share|improve this question









New contributor




Hau Jia Hung is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.









share|improve this question




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edited 33 mins ago









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asked 43 mins ago









Hau Jia Hung

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New contributor




Hau Jia Hung is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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New contributor





Hau Jia Hung is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.






Hau Jia Hung is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.












  • Welcome to Code Review. Please fix your indentation. The easiest way to post core is to paste it into the question editor, highlight it, and press Ctrl-K to mark it as a code block. Also tell us what the code accomplishes — see How to Ask.
    – 200_success
    39 mins ago


















  • Welcome to Code Review. Please fix your indentation. The easiest way to post core is to paste it into the question editor, highlight it, and press Ctrl-K to mark it as a code block. Also tell us what the code accomplishes — see How to Ask.
    – 200_success
    39 mins ago
















Welcome to Code Review. Please fix your indentation. The easiest way to post core is to paste it into the question editor, highlight it, and press Ctrl-K to mark it as a code block. Also tell us what the code accomplishes — see How to Ask.
– 200_success
39 mins ago




Welcome to Code Review. Please fix your indentation. The easiest way to post core is to paste it into the question editor, highlight it, and press Ctrl-K to mark it as a code block. Also tell us what the code accomplishes — see How to Ask.
– 200_success
39 mins ago















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