I wrote a program for a college assignment, and I'd like to receive some pointers on making my code a little more efficient. It'd be much appreciated. I'm still new to coding, so I apologize if my code is horrendous.
package lab07;
import java.util.Scanner;
public class Lab07 {
public static int reverse(int number){
int result = 0;
while (number !=0){
int remainder = number % 10;
result = result * 10 + remainder;
number = number / 10;
}
return result;
}
public static boolean isPalindrome(int input){
int Palindrome = reverse(input);
if (Palindrome == input){
return true;
}
else
return false;
}
public static void main(String[] args) {
int integer = 0;
Scanner input = new Scanner(System.in);
System.out.print("Enter a positive, multi-digit integer: ");
integer = input.nextInt();
while (integer <= 9 && integer > 0)
{
System.out.println(integer + " is a single digit. Please re-enter another integer: ");
integer = input.nextInt();
if (isPalindrome(integer) && (integer > 0 && integer > 9))
{
System.out.println(integer + " is a palindrome");
return;
}
else if (!isPalindrome(integer) && (integer > 0 && integer > 9))
{
System.out.println(integer + " is not a palindrome");
return;
}
}
while (integer < 0)
{
System.out.println(integer + " is negative. Please re-enter another integer: ");
integer = input.nextInt();
if (isPalindrome(integer) && (integer > 0 && integer > 9))
{
System.out.println(integer + " is a palindrome");
return;
}
else if (!isPalindrome(integer) && (integer > 0 && integer > 9))
{
System.out.println(integer + " is not a palindrome");
return;
}
while (integer <= 9 && integer > 0)
{
System.out.println(integer + " is a single digit. Please re-enter another integer: ");
integer = input.nextInt();
if (isPalindrome(integer) && (integer > 0 && integer > 9))
{
System.out.println(integer + " is a palindrome");
return;
}
else if (!isPalindrome(integer) && (integer > 0 && integer > 9))
{
System.out.println(integer + " is not a palindrome");
return;
}
}
}
while (integer > 9){
if (isPalindrome(integer) && (integer > 0 && integer > 9))
{
System.out.println(integer + " is a palindrome");
return;
}
else if (!isPalindrome(integer) && (integer > 0 && integer > 9))
{
System.out.println(integer + " is not a palindrome");
return;
}
}
}
}
Sorry I didn't specify this before but I'm in an Intro to Programming class, and our professor hasn't taught us how to reverse strings. These were his instructions:
The program should ask the end user to enter an integer. Use the isPalidrome
isPalidromemethod to invoke the reverse method, and report whether the the integer is a palindrome. Any one-digit integer or negative integer integer should be rejected with the specific error message (negative or or one digit), and then the program should ask the user to re-enter the the integer. Hint: To reverse the digits of a number, try this routine routine:int result = 0; while (number != 0) { // e.g. number = 123 // Iteration 1 Iteration 2 Iteration 3 int remainder = number % 10; // remainder = 3 remainder = 2 remainder = 1 result = result * 10 + remainder; // result = 3 result = 32 result = 321 number = number / 10; // number = 12 number = 1 number = 0 } // result contains the reverse of number
My solution:
package lab07;
import java.util.Scanner;
public class Lab07 {
public static int reverse(int number){
int result = 0;
while (number !=0){
int remainder = number % 10;
result = result * 10 + remainder;
number = number / 10;
}
return result;
}
public static boolean isPalindrome(int input){
int Palindrome = reverse(input);
if (Palindrome == input){
return true;
}
else
return false;
}
public static void main(String[] args) {
int integer = 0;
Scanner input = new Scanner(System.in);
System.out.print("Enter a positive, multi-digit integer: ");
integer = input.nextInt();
while (numberinteger !<= 9 && integer > 0)
{
System.out.println(integer + " is a single digit. Please re-enter another integer: ");
integer = input.nextInt();
if (isPalindrome(integer) && (integer > 0 && integer > 9))
{
System.out.println(integer + " is //a epalindrome");
return;
}
else if (!isPalindrome(integer) && (integer > 0 && integer > 9))
{
System.gout.println(integer number+ =" 123is not a palindrome");
return;
}
}
// Iteration 1while (integer < 0)
{
Iteration 2 IterationSystem.out.println(integer 3+ " is negative. Please re-enter another integer: ");
int remainder integer = numberinput.nextInt();
% 10; // remainder = 3 if (isPalindrome(integer) && (integer > 0 && remainderinteger => 29))
remainder = 1 {
result = result * 10 System.out.println(integer + remainder;" is a palindrome");
// result = 3 result = 32 return;
result = 321 }
number = number / 10; else if (!isPalindrome(integer) && (integer > 0 && integer > 9))
// number = 12 {
number = 1 number System.out.println(integer + " is not a palindrome");
return;
}
while (integer <= 9 && integer > 0)
{
System.out.println(integer + " is a single digit. Please re-enter another integer: ");
integer = input.nextInt();
if (isPalindrome(integer) && (integer > 0 && integer > 9))
{
System.out.println(integer + " is a palindrome");
return;
}
else if (!isPalindrome(integer) && (integer > 0 //&& resultinteger contains> the9))
reverse of number {
System.out.println(integer + " is not a palindrome");
return;
}
}
}
while (integer > 9){
if (isPalindrome(integer) && (integer > 0 && integer > 9))
{
System.out.println(integer + " is a palindrome");
return;
}
else if (!isPalindrome(integer) && (integer > 0 && integer > 9))
{
System.out.println(integer + " is not a palindrome");
return;
}
}
}
}
He provided the reverse method for us, I wouldn't have know how to actually reverse the integer on my own to be honest. However I appreciate the help on determining the palindrome.
