Which statement will empty the contents of a StringBuilder variable named sb?

The correct answer is C. sb.delete(0, sb.length());. To clear a StringBuilder variable, use its delete method with a start index of 0 and an end index equal to its current length, effectively removing all characters.

Working with Selected Classes from the Java API

Question

Options

Asb.deleteAll;
Bsb.delete(0, sb.size());
Csb.delete(0, sb.length());
Dsb.removeAll();

How the community answered

(26 responses)

A
4% (1)
B
4% (1)
C
85% (22)
D
8% (2)

Why each option

To clear a `StringBuilder` variable, use its `delete` method with a start index of 0 and an end index equal to its current length, effectively removing all characters.

Asb.deleteAll;

The `StringBuilder` class does not have a method named `deleteAll`.

Bsb.delete(0, sb.size());

The `StringBuilder` class uses the `length()` method to get its current length, not `size()`.

Csb.delete(0, sb.length());Correct

The `StringBuilder.delete(int start, int end)` method removes the characters in a substring of this sequence. Passing `0` as the start index and `sb.length()` as the end index will delete all characters, making the `StringBuilder` empty.

Dsb.removeAll();

The `StringBuilder` class does not have a method named `removeAll`.

Concept tested: StringBuilder manipulation methods

Source: https://docs.oracle.com/javase/8/docs/api/java/lang/StringBuilder.html#delete-int-int-

Topics

#StringBuilder#String manipulation#API methods

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