Given: 1. public class TestString3 { 2. public static void main(String[] args) { 3. // insert code here 5. System.out.println(s); 6. } 7. } Which two code fragments, inserted independently at line 3, generate the output 4247? (Choose two.) A. String s = “123456789”; s = (s-”123”).replace(1,3,”24”) - “89”; B. StringBuffer s = new StringBuffer(”123456789”); s.delete(0,3).replace( 1,3, “24”).delete(4,6); C. StringBuffer s = new StringBuffer(”123456789”); s.substring(3,6).delete( 1 ,3).insert( 1, “24”); D. StringBuilder s = new StringBuilder(”123456789”); s.substring(3,6).delete( 1 ,2).insert( 1, “24”); E. StringBuilder s = new StringBuilder(”123456789”); s.delete(0,3).delete( 1 ,3).delete(2,5).insert( 1, “24”);

  1. A

  2. B

  3. C

  4. D

  5. E


Correct Option: B,E

AI Explanation

To determine which code fragments inserted independently at line 3 generate the output 4247, let's go through each option:

Option A) String s = "123456789"; s = (s-"123").replace(1,3,"24") - "89"; This code will not compile because you cannot subtract a string from another string. Additionally, the replace() method does not have a subtract operator. Therefore, this option is incorrect.

Option B) StringBuffer s = new StringBuffer("123456789"); s.delete(0,3).replace(1,3, "24").delete(4,6); This code fragment will generate the output 4247.

  • The delete(0,3) method deletes the characters from index 0 to index 3 in the string, resulting in "456789".
  • The replace(1,3, "24") method replaces the characters from index 1 to index 3 with "24", resulting in "424789".
  • The delete(4,6) method deletes the characters from index 4 to index 6 in the string, resulting in "4247".

Therefore, this option is correct.

Option C) StringBuffer s = new StringBuffer("123456789"); s.substring(3,6).delete(1 ,3).insert(1, "24"); This code will not generate the output 4247.

  • The substring(3,6) method returns the substring from index 3 to index 6, resulting in "456".
  • The delete(1,3) method deletes the characters from index 1 to index 3 in the substring, resulting in "46".
  • The insert(1, "24") method inserts the string "24" at index 1 in the substring, resulting in "4246".

Therefore, this option is incorrect.

Option D) StringBuilder s = new StringBuilder("123456789"); s.substring(3,6).delete(1,2).insert(1, "24"); This code will not generate the output 4247.

  • The substring(3,6) method returns the substring from index 3 to index 6, resulting in "456".
  • The delete(1,2) method deletes the character at index 1 in the substring, resulting in "46".
  • The insert(1, "24") method inserts the string "24" at index 1 in the substring, resulting in "4246".

Therefore, this option is incorrect.

Option E) StringBuilder s = new StringBuilder("123456789"); s.delete(0,3).delete(1,3).delete(2,5).insert(1, "24"); This code fragment will generate the output 4247.

  • The delete(0,3) method deletes the characters from index 0 to index 3 in the string, resulting in "456789".
  • The delete(1,3) method deletes the characters from index 1 to index 3 in the string, resulting in "479".
  • The delete(2,5) method deletes the characters from index 2 to index 5 in the string, resulting in "47".
  • The insert(1, "24") method inserts the string "24" at index 1 in the string, resulting in "4247".

Therefore, this option is correct.

The correct answers are B and E.

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