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javastringstringbuilder

Time complexity of StringBuilder length() method

What is the time complexity of length() method from StringBuilder class?

String str = "hello";
StringBuilder sb = new StringBuilder(str);

System.out.println(sb.length()); // should print 5

My assumption is O(n) where n is number of characters in the string, similar to length() from String class.

Solution

  • This is a member variable in StringBuilder class:

    /**
 * The count is the number of characters used.
 */
int count;

    And this is the code of length():

    /**
 * Returns the length (character count).
 *
 * @return  the length of the sequence of characters currently
 *          represented by this object
 */
@Override
public int length() {
    return count;
}

    What do you think?