I wrote a piece of code for a class homework. However I thought it was quite long! Is there a more optimized way to do this?
String text = input.readLine();
int num = (text.length())/2;
double letter = (double)(text.length())/2;
String s1 = text.substring(0,num);
int u1 = Integer.parseInt(s1);
if (letter%1==0) {
StringBuffer s2 = new StringBuffer(text.substring(num));
s2 = s2.reverse();
String t2 = s2.toString();
int u2 = Integer.parseInt(t2);
if (u1==u2) {
System.out.println("Palindrome");
} else {
System.out.println("FAIL");
}
} else {
StringBuffer s2 = new StringBuffer(text.substring(num+1));
s2= s2.reverse();
String t2 = s2.toString();
int u2 = Integer.parseInt(t2);
if (u1==u2) {
System.out.println("Palindrom");
}else {
System.out.println("FAIL");
}
}
You don't need to convert the string back to number in order to compare them. You can use string's equals() method to check if they are equal. Check this out (with necessary changes this will work for any string though, not just numbers).
int num = 12300321;
String numString = String.valueOf(num);
String reverseNumString = new StringBuilder(numString).reverse().toString();
if(numString.equals(reverseNumString)) {
System.out.println(num + " is a Palindrome!");
}
else {
System.out.println(num + " is not a Palindrome!");
}
Output:
12300321 is a Palindrome!
Alternate method (using only number manipulation; will work for integers only)
int num = 12300321;
int numCopy = num;
int reverseNumInt = 0;
while(numCopy != 0) {
reverseNumInt = reverseNumInt * 10 + numCopy % 10;
numCopy /= 10;
}
if(reverseNumInt == num) {
System.out.println(num + " is a Palindrome!");
}
else {
System.out.println(num + " is not a Palindrome!");
}
Your code works, but handling the numbers digit by digit is simpler and more readable:
public static boolean isPalindromic(String num) {
for(int i = 0, len = num.length() ; i < len/2 ; i++) {
if(num.charAt(i) != num.charAt(num.charAt(len-i-1))) return false;
}
return true;
}
Related
public class Car {
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
int n = in.nextInt();
System.out.println(n+"!="+factorial(n));
}
public static int factorial(int num) {
return (num == 0) ? 1 : num * factorial (num - 1);
}
}
how make this code to text in console 3! = 1*2*3 = 6?
Don't use recursion for this. Besides, it isn't really efficient or necessary.
Scanner in = new Scanner(System.in);
int n = in.nextInt();
int fact = 1;
String s = n + "! = 1";
for (int i = 2; i <= n; i++) {
fact *= i;
s += "*" + i;
}
s += " = ";
System.out.println(s + fact);
There can be many ways to do it e.g. you can build the required string or print the trail while calculating the factorial. In the following example, I have done the former.
As an aside, you should check the input whether it is a positive integer.
import java.util.Scanner;
public class Car {
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
System.out.print("Enter a positive integer: ");
int n = in.nextInt();
if (n >= 0) {
StringBuilder strFact = new StringBuilder();
int fact = factorial(n, strFact);
if (strFact.length() > 0) {
// Delete the last '*'
strFact.deleteCharAt(strFact.length() - 1);
System.out.println(n + "!= " + strFact + " = " + fact);
} else {
System.out.println(n + "!= " + fact);
}
} else {
System.out.println("This is an invalid input.");
}
}
public static int factorial(int num, StringBuilder strFact) {
int fact;
if (num == 0) {
fact = 1;
} else {
fact = num * factorial(num - 1, strFact);
strFact.append(num + "*");
}
return fact;
}
}
A sample run:
Enter an integer: 3
3!= 1*2*3 = 6
import java.util.*;
public class HangManP5
{
public static void main(String[] args)
{
int attempts = 10;
int wordLength;
boolean solved;
Scanner k = new Scanner(System.in);
System.out.println("Hey, what's your name?");
String name = k.nextLine();
System.out.println(name+ ", hey! This is a hangman game!\n");
RandomWord(word);
int len = word.length();
char[] temp = new char[len];
for(int i = 0; i < temp.length; i++)
{
temp[i] = '*';
}
System.out.print("\n");
System.out.print("Word to date: ");
while (attempts <= 10 && attempts > 0)
{
System.out.println("\nAttempts left: " + attempts);
System.out.print("Enter letter: ");
String test = k.next();
if(test.length() != 1)
{
System.out.println("Please enter 1 character");
continue;
}
char testChar = test.charAt(0);
int foundPos = -2;
int foundCount = 0;
while((foundPos = word.indexOf(testChar, foundPos + 1)) != -1)
{
temp[foundPos] = testChar;
foundCount++;
len--;
}
if(foundCount == 0)
{
System.out.println("Sorry, didn't find any matches for " + test);
}
else
{
System.out.println("Found " + foundCount + " matches for " + test);
}
for(int i = 0; i < temp.length; i++)
{
System.out.print(temp[i]);
}
System.out.println();
if(len == 0)
{
break; //Solved!
}
attempts--;
}
if(len == 0)
{
System.out.println("\n---------------------------");
System.out.println("Solved!");
}
else
{
System.out.println("\n---------------------------");
System.out.println("Sorry you didn't find the mystery word!");
System.out.println("It was \"" + word + "\"");
}
}
public static String RandomWord(String word)
{
//List of words
Random r = new Random();
int a = 1 + r.nextInt(5);
if(a == 1)
{
word=("Peace");
}
if(a == 2)
{
word=("Nuts");
}
if(a == 3)
{
word=("Cool");
}
if(a == 4)
{
word=("Fizz");
}
if(a == 5)
{
word=("Awesome");
}
return (word);
}
}
Ok, so this is my code for a hangman game, the only thing I have left to do is to get my program to randomize one of the words, which it should do in the method successfully. But the only problem I'm having is getting the String variable "word" to go back to the main class (there are errors underlining all the "word" variables in the main class).
If I could get help with either this or another way to produce a random word from a list, that would be amazing.
In java, parameters are passed by value and not by reference. Therefore, you cannot change the reference of a parameter.
In your case, you need to do:
public static String getRandomWord() {
switch(new Random().nextInt(5)) {
case 0:
return "Peace";
case 1:
return "Nuts";
// ...
default:
throw new IllegalStateException("Something went wrong!");
}
}
And in main:
// ...
String word = getRandomWord();
int len = word.length();
// ...
You can't modify the caller's reference.
RandomWord(word);
needs to be something like
word = RandomWord(word);
Also, by convention, Java methods start with a lower case letter. And, you could return the word without passing one in as an argument and I suggest you save your Random reference and use an array like
private static Random rand = new Random();
public static String randomWord() {
String[] words = { "Peace", "Nuts", "Cool", "Fizz", "Awesome" };
return words[rand.nextInt(words.length)];
}
And then call it like
word = randomWord();
I'm trying to make a simple calculator in Java which takes input in the form of a string and does a simple '+' and '-' operation.
Single digit inputs work but my problem is when i try to implement this for double digit
input string is: 5+20+5+11
list 1 = [5, 20, 2, 0, 5, 11, 1]
list 2 = [+, +, +]
Answer:27
I need to find a way where after storing [5] in list1 how i can add [5,20] instead of [5,20,2,0] which the current code is doing.
public int calC(String input) {
int len = input.length();
ArrayList list1 = new ArrayList();
ArrayList list2 = new ArrayList();
for (int i = 0; i < len; i++) {
if ((input.charAt(i) != '+') && (input.charAt(i) != '-')) {
// check if the number is double-digit
if ((i + 1 <= len - 1)) {
if ((input.charAt(i + 1) != '+')&& (input.charAt(i + 1) != '-')) {
String temp = "";
temp = temp + input.charAt(i) + input.charAt(i + 1);
int tempToInt = Integer.parseInt(temp);
// adding the double digit number
list1.add(tempToInt);
}
// add single digit number
list1.add(input.charAt(i) - '0');
}
} else {
// adding the symbols
list2.add(input.charAt(i));
}
}
int result = 0;
result = result + (int) list1.get(0);
for (int t = 0; t < list2.size(); t++) {
char oper = (char) list2.get(t);
if (oper == '+') {
result = result + (int) list1.get(t + 1);
} else if (oper == '-') {
result = result - (int) list1.get(t + 1);
}
}
return result;
}
Edit: working version
#Ker p pag thanks for the updated methods
input string is: 5+20+5+11
[5, 20, 5, 11]
[+, +, +]
Answer:41
I'll need to try to implement this with stack as suggested but the current version works
static boolean isDigit(char check) {
if (Character.isDigit(check)) {
return true;
}
return false;
}
public static int calC(String input) {
int len = input.length();
ArrayList list1 = new ArrayList();
ArrayList list2 = new ArrayList();
for (int i = 0; i < len; i++) {
if ((i + 1 <= len - 1)) {
if (isDigit(input.charAt(i)) && isDigit(input.charAt(i + 1))) {
String temp = input.charAt(i) + "" + input.charAt(i + 1);
int toInt = Integer.parseInt(temp);
list1.add(toInt);
i = i+1;
} else if (isDigit(input.charAt(i))) {
list1.add(input.charAt(i)- '0');
} else {
list2.add(input.charAt(i));
}
}
}
int result = 0;
result = result + (int) list1.get(0);
for (int t = 0; t < list2.size(); t++) {
char oper = (char) list2.get(t);
if (oper == '+') {
result = result + (int) list1.get(t + 1);
} else if (oper == '-') {
result = result - (int) list1.get(t + 1);
}
}
return result;
}
Here is the code:
String a = "5+20-15+8";
System.out.println(a);
String operators[]=a.split("[0-9]+");
String operands[]=a.split("[+-]");
int agregate = Integer.parseInt(operands[0]);
for(int i=1;i<operands.length;i++){
if(operators[i].equals("+"))
agregate += Integer.parseInt(operands[i]);
else
agregate -= Integer.parseInt(operands[i]);
}
System.out.println(agregate);
If you want the result 41 for input string "5+20+5+11",
why not use ScriptEngineManager with JavaScript engine,
public double calC(String input) {
int result = 0;
ScriptEngineManager mgr = new ScriptEngineManager();
ScriptEngine engine = mgr.getEngineByName("JavaScript");
return (Double)engine.eval(input);
}
But note that the return type is double here.
If you want only int as return type in this case, try with this
return new BigDecimal(engine.eval(input).toString()).intValue();
Another way to think about this:
public class InlineParsing {
public static void main(String []args){
String input = "5-2+20+5+11-10";
input = input.replace(" ","");
String parsedInteger = "";
String operator = "";
int aggregate = 0;
for (int i = 0; i < input.length(); i++){
char c = input.charAt(i);
if (Character.isDigit(c)) {
parsedInteger += c;
}
if (!Character.isDigit(c) || i == input.length()-1){
int parsed = Integer.parseInt(parsedInteger);
if (operator == "") {
aggregate = parsed;
}
else {
if (operator.equals("+")) {
aggregate += parsed;
}else if (operator.equals("-")){
aggregate -= parsed;
}
}
parsedInteger ="";
operator = ""+c;
}
}
System.out.println("Sum of " + input+":\r\n" + aggregate);
}
}
It's basically a state machine that traverses over each char.
Iterate over each char:
if current char is a digit, add to current number buffer
if current char is not a digit or we're parsing the last digit
if an operator has been parsed use that to add the newly parsed number to the sum
if no operator has been parsed, set sum to current parsed number
clear current number buffer
store current char as operator
I agree that stack is the best solution,but still giving an alternative way
of doing this.
String input = "5+20+11+1";
StringBuilder sb = new StringBuilder();
List<Integer> list1 = new ArrayList<Integer>();
List<Character> list2 = new ArrayList<Character>();
char[] ch = input.toCharArray();
for(int i=0;i<ch.length;i++)
{
if(ch[i]!='+')
{
sb.append(ch[i]);
}else
{
list2.add(ch[i]);
list1.add(Integer.valueOf(sb.toString()));
sb.setLength(0);
}
}
if(sb.length()!=0)
list1.add(Integer.valueOf(sb.toString()));
System.out.println(list1.size());
for(Integer i:list1)
{
System.out.println("values"+i);
}
for storing the input to the list you could try this snippet
for (int i = 0; i < input.length() - 1; i++) {
// make a method
// check if current character is number || check if current
// character is number and the next character
if (isDigit(input.charAt(i)) && isDigit(input.charAt(i + 1))) {
list.add(input.charAt(i) +""+ input.charAt(i + 1));
} else if (isDigit(input.charAt(i))) {
list.add(input.charAt(i));
}else{
operator.add(input.charAt(i));
}
}
//check if it is a number
public boolean isDigit(char input){
if(input == '1' ||
input == '2' ||
input == '3' ||
input == '4' ||
input == '5' ||
input == '6' ||
input == '7' ||
input == '8' ||
input == '9' ||
input == '0')
return true;
return false;
}
I could advise you to use Exp4j. It is easy to understand as you can see from the following example code:
Expression e = new ExpressionBuilder("3 * sin(y) - 2 / (x - 2)")
.variables("x", "y")
.build()
.setVariable("x", 2.3)
.setVariable("y", 3.14);
double result = e.evaluate();
Especially for the case of using more complex expression this could be a better choice.
private static int myCal() {
String[] digits = {
"1",
"2",
"3",
"4",
"5"
};
String[] ops = {
"+",
"+",
"+",
"-"
};
int temp = 0;
int res = 0;
int count = ops.length;
for (int i = 0; i < digits.length; i++) {
res = Integer.parseInt(digits[i]);
if (i != 0 && count != 0) {
count--;
switch (ops[i - 1]) {
case "+":
temp = Math.addExact(temp, res);
break;
case "-":
temp = Math.subtractExact(temp, res);
break;
case "*":
temp = Math.multiplyExact(temp, res);
break;
case "/":
temp = Math.floorDiv(temp, res);
break;
}
}
}
return temp;
}
You can check this code that I created using array only. I also tried several arithmetic problems also your given problem.
Please see also the comments within the method.
public static String Calculator(String str) {
// will get all numbers and store it to `numberStr`
String numberStr[] = str.replaceAll("[+*/()-]+"," ").split(" ");
// will get all operators and store it to `operatorStr`
String operatorStr[] = str.replaceAll("[0-9()]+","").split("");
int total = Integer.parseInt(numberStr[0]);
for (int i=0; i<operatorStr.length; i++) {
switch (operatorStr[i]) {
case "+" :
total += Integer.parseInt(numberStr[i+1]);
break;
case "-" :
total -= Integer.parseInt(numberStr[i+1]);
break;
case "*" :
total *= Integer.parseInt(numberStr[i+1]);
break;
case "/" :
total /= Integer.parseInt(numberStr[i+1]);
break;
}
if(i+2 >= operatorStr.length) continue; // if meets the last operands already
numberStr[i+1] = String.valueOf(total);
}
return String.valueOf(total);
}
import java.util.ArrayList;
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
ArrayList<Character> listOfOpertionsCharFORM = new ArrayList<>();
ArrayList<Character> listOfNumbersCharFORM = new ArrayList<>();
ArrayList<Integer> listOfNumbersINTEGERFORM = new ArrayList<>();
int Total = 0;
Scanner sc = new Scanner(System.in);
String input;
System.out.print("Please enter your math equation :");
input = sc.nextLine();
System.out.println("string is : " + input);
separator();
char[] convertAllToChar = input.toCharArray();
for (char inputToChar : convertAllToChar) {
System.out.println("convertAllToChar " + inputToChar);
}
for (int i = 0; i < input.length(); i++) {
if (convertAllToChar[i] == '+') {
listOfOpertionsCharFORM.add(convertAllToChar[i]);
}
if (convertAllToChar[i] == '-') {
listOfOpertionsCharFORM.add(convertAllToChar[i]);
}
if (convertAllToChar[i] == '*') {
listOfOpertionsCharFORM.add(convertAllToChar[i]);
}
if (convertAllToChar[i] == '/') {
listOfOpertionsCharFORM.add(convertAllToChar[i]);
}
if (Character.isDigit(convertAllToChar[i])) {
listOfNumbersCharFORM.add(convertAllToChar[i]);
}
}
separator();
for (Character aa : listOfOpertionsCharFORM) {
System.out.println("list Of Operations Char FORM " + aa);
}
separator();
for (Character aa : listOfNumbersCharFORM) {
System.out.println("list Of Numbers Char FORM " + aa);
}
separator();
for (Character aa : listOfNumbersCharFORM) {
if (aa == '0') listOfNumbersINTEGERFORM.add(0);
if (aa == '1') listOfNumbersINTEGERFORM.add(1);
if (aa == '2') listOfNumbersINTEGERFORM.add(2);
if (aa == '3') listOfNumbersINTEGERFORM.add(3);
if (aa == '4') listOfNumbersINTEGERFORM.add(4);
if (aa == '5') listOfNumbersINTEGERFORM.add(5);
if (aa == '6') listOfNumbersINTEGERFORM.add(6);
if (aa == '7') listOfNumbersINTEGERFORM.add(7);
if (aa == '8') listOfNumbersINTEGERFORM.add(8);
if (aa == '9') listOfNumbersINTEGERFORM.add(9);
}
for (Integer aaa : listOfNumbersINTEGERFORM) {
System.out.println("list Of Numbers INTEGER FORM " + aaa);
}
separator();
separator();
separator();
System.out.print(listOfNumbersINTEGERFORM);
System.out.print(listOfOpertionsCharFORM);
System.out.println();
System.out.println();
if (listOfNumbersINTEGERFORM.size() == (listOfOpertionsCharFORM.size() + 1)) {
for (int i = 0; i < listOfOpertionsCharFORM.size(); i++) {
System.out.println("i :" + i);
if (listOfOpertionsCharFORM.get(i) == '+') if (i == 0) {
Total = Total + listOfNumbersINTEGERFORM.get(i) + listOfNumbersINTEGERFORM.get(i + 1);
System.out.println("total : " + Total);
separatorShort();
} else {
Total = Total + listOfNumbersINTEGERFORM.get(i + 1);
System.out.println("total : " + Total);
separatorShort();
}
if (listOfOpertionsCharFORM.get(i) == '-') if (i == 0) {
Total = Total + listOfNumbersINTEGERFORM.get(i) - listOfNumbersINTEGERFORM.get(i + 1);
System.out.println("total : " + Total);
separatorShort();
} else {
Total = Total - listOfNumbersINTEGERFORM.get(i + 1);
System.out.println("total : " + Total);
separatorShort();
}
if (listOfOpertionsCharFORM.get(i) == '*') if (i == 0) {
Total = Total + listOfNumbersINTEGERFORM.get(i) * listOfNumbersINTEGERFORM.get(i + 1);
System.out.println("total : " + Total);
separatorShort();
} else {
Total = Total * listOfNumbersINTEGERFORM.get(i + 1);
System.out.println("total : " + Total);
separatorShort();
}
if (listOfOpertionsCharFORM.get(i) == '/') if (i == 0) {
Total = Total + listOfNumbersINTEGERFORM.get(i) / listOfNumbersINTEGERFORM.get(i + 1);
System.out.println("total : " + Total);
separatorShort();
} else {
Total = Total / listOfNumbersINTEGERFORM.get(i + 1);
System.out.println("total : " + Total);
separatorShort();
}
}
} else {
System.out.println("*********###############**********");
System.out.println("** your input not correct input **");
System.out.println("*********###############**********");
}
System.out.println("*** Final Answer *** : " + Total);
}
public static void separator() {
System.out.println("___________________________________");
}
public static void separatorShort() {
System.out.println("_____________");
}
So I have to read a sequence of numbers from the console ( 1 to 50 numbers), none of which are equal and print out the numbers for which is true that a|b == c|d (example: 5|32 == 53|2), but I get an NubmferFormatException each time. Why?
import java.util.Scanner;
public class StuckNumbers {
public static void main(String[] args) {
// create Scanner
Scanner input = new Scanner(System.in);
// input count and declare array
System.out.println("input number of numbers");
int count = input.nextInt();
int[] numbers = new int[count];
// check if count is between 1 and 50
if (count < 1 && count > 50) {
System.out.println("Wrong input. Input a number between 1 and 50");
count = input.nextInt();
}
// input n numbers
for (int i : numbers) {
i = input.nextInt();
// check if i = j
for (int j : numbers) {
if (i == j) {
System.out
.println("All numbers must be dist75inct. Try again.");
i = input.nextInt();
}
}
}
for (int i = 0; i < count; i++) {
for (int j = 0; j < count; j++) {
if (stuckNumbers(numbers[i], numbers[j]) == stuckNumbers(
numbers[j], numbers[i])) {
System.out.println(i + "|" + j + " == " + j + "|" + i);
}
}
}
input.close();
}
public static int stuckNumbers(int a, int b) {
String firstNum = "a";
String secondNum = "b";
String res = "ab";
int result = Integer.parseInt(res);
return result;
}
}
Look at these lines:
String res = "ab";
int result = Integer.parseInt(res);
"ab" is not a number, so you're going to get a NumberFormatException when you try to parse it as an integer.
Change the firstNum and SecondNum variables from "a" and "b" to Integer.toString(a); OR String.valueOf(a); and similar for b.
public static int stuckNumbers(int a, int b) {
String firstNum = String.valueOf(a);
String secondNum = String.valueOf(b);
String res = "";
res.concat(firstNum);
res.concat(secondNum);
int result = Integer.parseInt(res);
return result;
}
I hope this will remove any Exception being thrown.
I am trying to create a Palindrome tester in java using a method.. This is what I have so far. It is so close I just can't figure out why it won't say that it IS a palindrome and reverse it.
System.out.println("Fun with Palindromes!!");
Scanner in = new Scanner(System.in);
System.out.println("Enter the potential palindrome (or enter exit to quit): ");
String x = in.nextLine();
while(!x.equals("exit"))
{
String t = x.toLowerCase();
String u = CleanUpString(t);
Boolean wordCheck = checkPalindrome(u);
int wordCount = x.length();
String rev = "";
for(int i = 0; i <x.length(); i++)
{
rev = x.charAt(i)+rev;
}
if(wordCheck == true)
{
System.out.println("The orginal string\"" + u + "\" contains" + wordCount + "characters." );
System.out.println("The converted string\"" + rev + "\"is a palindrome");
}
else if(wordCheck == false)
{
System.out.println("The string \"" + u + "\" contains " + wordCount + " characters");
System.out.println("\"" + rev + "\" is not a palindrome");
}
System.out.println("\nEnter the potential palindrome, or enter exit to quit: ");
x = in.nextLine();
}
}
public static String CleanUpString(String words)
{
words = words.replace(".","");
words = words.replace("," ,"");
words = words.replace(":","");
words = words.replace("!","");
return words;
}
public static boolean checkPalindrome(String baseball)
{
String rev = "";
for(int i = 0; i<baseball.length()-1; i++)
{
rev = baseball.charAt(i) + rev;
}
if(rev.equals(baseball))
return true;
else
return false;
}
}
Here is the code I used to determine whether a string is Palindrome String or not:
private static boolean checkPalindrome(String str){
if (str == null)
return false;
int len = str.length();
for (int i=0;i<len/2 ; i++){
if (str.charAt(i) != str.charAt(len - i - 1)){
return false;
}
}
return true;
}
For reversing strings, you can simply use:
String reverse = new StringBuffer(string).reverse().toString();
Hope these can help you.
Use StringUtils for this
import org.apache.commons.lang.StringUtils;
boolean isPalindrome(String word) {
return StringUtils.reverse(word).equals(word);
}
Here is another option
public class PalindromeTester {
public static void main(String[] args) {
try {
String s = args[0];
int i = args[0].length()-1;
int i2 = args[0].length();
char [] chrs = new char[i2];
for ( int i3 = i; i3 > -1; i3-- ) {
chrs[i2-i3-1] = (s.charAt(i3) );
}
String s2 = String.valueOf(chrs);
if ( s2.equals(s) ) {
System.out.println( s + " is a palindrome!");
} else {
System.out.println( s + " is not a palindrome");
}
} catch ( ArrayIndexOutOfBoundsException e ) {
System.out.println("Please enter at least one letter or digit!");
}
}
}
Here's how I did it:
public class palindromeTWO
{
public static void main(String[] args)
{
Scanner scan = new Scanner(System.in);
int right = 0;
int left = 1;
System.out.println("Please enter a word: ");
String word = scan.next();
int word_length = word.length();
while(word.charAt(right) == word.charAt(word_length - left) && left < (word_length / 2))
{
left++;
right++;
}
if(word.charAt(right) == word.charAt(word_length - left))
{
System.out.println("'" + word + "'" + " is a palindrome!");
}
else
{
System.out.println("'" + word + "'" + " is NOT a palindrome.");
}
}
}
1st implementation using recursion -
import java.util.ArrayList;
import java.util.stream.Collectors;
public class PalindromeManager {
private static String str = "ehcache";
private static ArrayList<String> list = new ArrayList<>();
public static void main(String[] args) {
test(str);
String output = list.stream().collect(Collectors.joining());
System.out.println(output);
if (output.equals(str)) {
System.out.println("it was palindrome");
} else {
System.out.println("Nope! it wasn't");
}
}
private static void test(String str) {
if (str.length() <= 0) {
return;
}
String lastChar = "" + str.charAt(str.length() - 1);
list.add(lastChar);
test(str.substring(0, str.length() - 1));
}
}
2nd implementation using iteration -
public class PalindromeManager2 {
private static String str = "ehcache";
public static void main(String[] args) {
int startIndex = 0;
int lastIndex = str.length() - 1;
boolean result = true;
while (true) {
if (startIndex >= lastIndex) {
break;
}
char first = str.charAt(startIndex);
char last = str.charAt(lastIndex);
/*if (first == ' ') {
startIndex++;
continue;
}
if (last == ' ') {
lastIndex--;
continue;
}*/
if (first != last) {
result = false;
break;
}
startIndex++;
lastIndex--;
}
if (result) {
System.out.println("Yes! It was");
} else {
System.out.println("Nope! it wasn't");
}
}
}
In checkPalindrome method change the condition of for loop from i<baseball.length()-1 to i<baseball.length().