How to make a program that returns the first recurring character in a string in Java? [closed]

I got a school assignment in computers in which I have to make a small program that returns the first recurring characters in a string using loops and conditional statements but I can't figure out how to so. Please help!

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3 Answers
3

The following code will do so:

String text = ""; // String that holds the text
int length = text.length();
outerloop:
for (int i = 0; i <= length - 1; i++) {
char curChar = text.charAt(i);
for (int j = i + 1; j <= length - 1; j++) {
if (curChar == text.charAt(j)) {
System.out.println("The first recurring character in string " + text + " is '" + curChar + "'.");
break outerloop;
}
}
}


But try doing things yourself!

Since it is a school assignment, I am not sure if you're going to be allowed to have the full code, but I'm sure this will at least help

Pseudo code:

string = "asda"

foreach letter in string DO
temp = string
temp.remove_char_from_string(letter)
if (letter in temp = true)
OUTPUT string.indexOf(letter)
exit foreach
endif
endfor


if (letter in string = true)

In Java 8, you can do it easily as:

public class HelloWorld {
public static void main(String... args) {
String s = "Hi, there";
Map<Character, Long> characterIntegerMap = s.chars()
.mapToObj(c -> (char) c)
.collect(Collectors.groupingBy(Character::valueOf, Collectors.counting()));
for (int i = 0, len = s.length(); i < len; ++i) {
Character c = s.charAt(i);
if (characterIntegerMap.get(Character.valueOf(c)) > 1) {
System.out.println(c);
break;
}
}
}
}


If you'd prefer a simpler version, you can just ignore map used here instead using this, which might tumble into performance issues when string is large:

map

for (int i = 0, len = s.length(); i < len; ++i) {
Character c = s.charAt(i);
if (i != s.lastIndexOf(c)) {
System.out.println(c);
break;
}
}