The following code should give me a String concatenated from all characters after a space in a sentence:
public class Main {
public static void main (String[] args) {
System.out.println(generateFromSentence("Hello World!"));
}
public static String generateFromSentence(String sentence) {
String output = String.valueOf(sentence.charAt(0));
for (int i = 0; i <= sentence.length(); i++) {
if (sentence.charAt(i) == ' '){
String following = String.valueOf(sentence.charAt(i+1));
output = output.concat(following);
}
}
return output;
}
}
Sadly it throws:
Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String index out of range: 12
at java.base/java.lang.StringLatin1.charAt(StringLatin1.java:47)
at java.base/java.lang.String.charAt(String.java:693)
at Main.generateFromSentence(Main.java:9)
at Main.main(Main.java:3)
I don’t understand why the index would be out of range, at
String output = String.valueOf(sentence.charAt(0));
I specify Index 0 – should be the first character of my string, right?
Thanks already.
>Solution :
Your issue is not in line String.valueOf(sentence.charAt(0)); but in line if (sentence.charAt(i) == ' '). The reason is your for loop stoping condition. You must use i < sentence.length() instead of i <= sentence.length() as follows:
public class Main {
public static void main (String[] args) {
System.out.println(generateFromSentence("Hello World!"));
}
public static String generateFromSentence(String sentence) {
String output = String.valueOf(sentence.charAt(0));
for (int i = 0; i <= sentence.length(); i++) {
if (sentence.charAt(i) == ' '){
String following = String.valueOf(sentence.charAt(i+1));
output = output.concat(following);
}
}
return output;
}
}
Keep in mind that indexes start at 0, so you can’t iterate over a List or Array starting at 0 up to and including the List or Array size.
Additionally, keep in mind that for the same reason your (and my) code above will fail if the sentence is "Hello World! " (mind the at the end of the sentence). The reason is the line String following = String.valueOf(sentence.charAt(i+1));. To get around this issue you need to add a condition to your if statement:
public class Main {
public static void main (String[] args) {
System.out.println(generateFromSentence("Hello World! "));
}
public static String generateFromSentence(String sentence) {
String output = String.valueOf(sentence.charAt(0));
for (int i = 0; i < sentence.length(); i++) {
if (sentence.charAt(i) == ' ' && ((i + 1) < sentence.length())){
String following = String.valueOf(sentence.charAt(i+1));
output = output.concat(following);
}
}
return output;
}
}