Given the code fragment: String digits = "0123456789"; System.out.println( digits.substring( digits.indexOf("4"), digits.indexOf("8"))).concat("89")); What is the result?

Question

Options

• A456789
• B45678
• C45678
• D3456789

• A
  78% (29)
• B
  14% (5)
• C
  5% (2)
• D
  3% (1)

Explanation

Option A (456789) is correct because digits.indexOf("4") returns 4 and digits.indexOf("8") returns 8, so substring(4, 8) yields "4567" - then .concat("89") appends "89", producing "456789".

Why the distractors fail:

• B/C (45678): This mistakes substring as inclusive on both ends - but Java's substring(start, end) excludes the end index, so index 8 ('8') is never included. These also ignore the .concat("89") call entirely.
• D (3456789): This suggests indexOf("4") returns 3, which would happen if someone confused the character '4' with a zero-based offset from '1' - but indexOf returns the actual position in the string, and '4' sits at index 4.

Memory tip: Think of substring(start, end) as a fence post - you start at the first post but stop before the last one. A quick way to verify: "0123456789".substring(4, 8) spans 4 characters (8 - 4 = 4), giving "4567", not five.

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