CODEWITHSUNDEEP
javastring
Murali
Murali

Reputation: 378

substring is not working

This is my previous question

In my above question's answer return id.substring(0, lastDot - 1); in this line lastDot is getting problem.

If I have the id 1.1 the in the above line lastDot value is 1 the substring is getting "".

How can I avoid the problem.

private String getParentId(String id) {
    int lastDot = id.lastIndexOf(".");
    if (lastDot == -1) {
        return null;
    }
    return id.substring(0, lastDot - 1);
}

Upvotes: 0

Views: 94

Answers (2)

Amer Qarabsa
Amer Qarabsa

Reputation: 6574

Check the java docs: https://docs.oracle.com/javase/8/docs/api/java/lang/String.html

The second parameter is the length of the string starting from the first parameter, so if you are always starting with index 0 , you do not need to subtract 1 

return id.substring(0, lastDot);

A more general approach would be to always subtract the first parameter

  int offset = 0;
return id.substring(offset, lastDot-offset);

Upvotes: 4

Eugene
Eugene

Reputation: 121068

 return id.substring(0, lastDot);

is what you meant probably. But think of the case when your id would be 1.2.3 what would like to return in this case? 1.2 or 2 or 1. At the moment your function will return 1.2 at it might be correct - but that depends on your needs.

Upvotes: 1

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