Java lastIndexOf always return -1 if the character is space and fromIndex is set

Question

Test Code

public class HelloWorld{
     public static void main(String []args){
        System.out.println("Hello World".lastIndexOf(' '));
        System.out.println("Hello World".lastIndexOf(' ', 1));
        System.out.println("Hello World".lastIndexOf('e'));
        System.out.println("Hello World".lastIndexOf('e', 1));
     }
}

Result

I expected the second result be 5 but it is -1. How can the first one is right but the second is wrong?

Checkout Documentation : @return the index of the last occurrence of the character in the * character sequence represented by this object that is less * than or equal to {@code fromIndex}, or {@code -1} * if the character does not occur before that point. — Abhishek, Jun 27 '17 at 09:02
From the javadoc : " if no such character occurs in this string _at or before_ position _fromIndex_, then -1 is returned." . — Arnaud, Jun 27 '17 at 09:02
Thx guys. I know -1 is not found but I didn't notice if right to left. The variable named fromIndex confused me and I assume it search the substring of start from fromIndex. — Joshua, Jun 27 '17 at 09:10

score 2 · Accepted Answer · answered Jun 27 '17 at 09:00

2

lastIndexOf() goes from right to left, so when it starts with index 1 (the second character, namely 'e'), it does not find a space (which has index 5).

answered Jun 27 '17 at 09:00

Roman Puchkovskiy

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score 2 · Answer 2 · answered Jun 27 '17 at 09:08

Simplest Way

lastIndexOf(int ch, int fromIndex) returns index of ch only if it occurs at or before fromIndex, Otherwise return -1.

System.out.println("Hello World".lastIndexOf(' ', 3));

returns -1.

System.out.println("He llo World".lastIndexOf(' ', 3));

returns 2.

Java lastIndexOf always return -1 if the character is space and fromIndex is set

2 Answers2