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.