英文:
Determing if an integer/string is a palindrome, and returning the reversed string/integer if it isn't
问题
public class PalindromeChecker {
public static void main(String[] args) {
// ... (unchanged code for user input)
if (userInput.equals("string")) {
System.out.println("Enter the string now:");
String s;
s = keyboard.nextLine();
if (isPalindromeString(s)) {
System.out.println("Yes, the string is a palindrome.");
} else {
System.out.println("No, the string is not a palindrome.");
System.out.println("The reverse of the string is: " + reverseString(s));
}
} else if (userInput.equals("integer")) {
System.out.println("Enter the number now:");
int i;
i = keyboard.nextInt();
if (isPalindromeInteger(i)) {
System.out.println("Yes, the integer is a palindrome.");
} else {
System.out.println("No, the integer is not a palindrome.");
System.out.println("The reverse of the integer is: " + reverseInteger(i));
}
keyboard.nextLine();
}
}
public static boolean isPalindromeInteger(int a) {
// ... (unchanged code for palindrome check)
}
public static boolean isPalindromeString(String s) {
// ... (unchanged code for palindrome check)
}
public static int reverseInteger(int a) {
// ... (unchanged code for integer reversal)
}
public static String reverseString(String s) {
// ... (unchanged code for string reversal)
}
public static boolean isEven(int a) {
// ... (unchanged code for checking evenness)
}
}
Please note that the provided code is unchanged except for wrapping it within a class called PalindromeChecker. The class encapsulation helps organize the code and is good practice in Java.
英文:
I'm trying to to determine if a string or integer is a palindrome (same, if reversed). I've written a few methods, however, when I run the code, I keep getting an error for my isPalindromeString() and isPalindromeInteger() methods, saying the methods "must return a boolean type." I have setup clauses in the methods to return true/false based on my if statements. Not sure what I'm doing wrong here. Any guidance would be appreciated. Thanks. PS: I'm trying to not use any arrays, data structures and/or class methods.
public static void main(String[] args) {
Scanner keyboard = new Scanner(System.in);
String userInput;
System.out.println("Would you like to enter a string or integer?");
userInput = keyboard.nextLine().toLowerCase();
while(!userInput.equals("string") && !userInput.equals("integer"))
{
System.out.println("Invalid input. Try again. ");
userInput = keyboard.nextLine().toLowerCase();
}
if(userInput.equals("string"))
{
System.out.println("Enter the string now: ");
String s;
s = keyboard.nextLine();
if(isPalindromeString(s))
{
System.out.println("Yes, the string is a palindrome.");
}
else
{
System.out.println("No, the string is not a palindrome.");
System.out.println("The reverse of the string is: " + reverseString(s));
}
}
else if(userInput.equals("integer"))
{
System.out.println("Enter the number now: ");
int i;
i = keyboard.nextInt();
if(isPalindromeInteger(i))
{
System.out.println("Yes, the integer is a palindrome.");
}
else
{
System.out.println("No, the integer is not a palindrome.");
System.out.println("The reverse of the integer is: " + reverseInteger(i));
}
keyboard.nextLine();
}
}
public static boolean isPalindromeInteger(int a)
{
int counter=0;
String s = Integer.toString(a);
int reverseCounter = s.length()-1;
if(isEven(s.length()))
{
while(counter!=(s.length()/2))
{
if(s.charAt(counter)!=s.charAt(reverseCounter))
{
return false;
}
counter++;
reverseCounter--;
}
return true;
}
else if(!isEven(s.length()))
{
while(counter!= (s.length()/2))
{
if(s.charAt(counter)!=s.charAt(reverseCounter))
{
return false;
}
counter++;
reverseCounter--;
}
return true;
}
}
public static boolean isPalindromeString(String s)
{
int counter=0;
int reverseCounter = s.length()-1;
if(isEven(s.length()))
{
while(counter!=(s.length()/2))
{
if(s.charAt(counter)!=s.charAt(reverseCounter))
{
return false;
}
counter++;
reverseCounter--;
}
return true;
}
else if(!isEven(s.length()))
{
while(counter!= (s.length()/2))
{
if(s.charAt(counter)!=s.charAt(reverseCounter))
{
return false;
}
counter++;
reverseCounter--;
}
return true;
}
}
public static int reverseInteger(int a)
{
String s = Integer.toString(a);
String temp = new String();
for(int i = (s.length()-1); i >=0; i--)
{
temp = temp + s.charAt(i);
}
int num = Integer.parseInt(temp);
return num;
}
public static String reverseString(String s)
{
String temp = new String();
for(int i = (s.length()-1); i >=0; i--)
{
temp = temp + s.charAt(i);
}
return temp;
}
public static boolean isEven(int a)
{
if(a % 2 ==0)
return true;
else
return false;
}
答案1
得分: 1
在你的 isPalindromeString() 和 isPalindromeInteger() 方法中，你的 if/elif 代码块之外缺少了一个返回语句。只需在 else if 检查之后添加 return false，你的代码就应该可以工作。
英文:
In both your isPalindromeString() and isPalindromeInteger() methods, you do not have a return statement outside of your if/elif blocks. Simply adding a return false after your else if check should make your code work.
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