Effective value comparison of StringBuilder objects

Question

Hi there,
I got questions in comments of the code. Can anyone help?
public class StringBuilderTest {
     public static void main(String[] args) {
          StringBuilder sb = new StringBuilder("abc");
          StringBuilder sb1 = new StringBuilder("abc");
          // only if sb = sb1 returns true, coz different object referenced
          if ( sb.equals(sb1)){
               System.out.println("equal value");
           * I think the following blocks both return true as a result but the second
           * block is better choice from a performance perspective.
           * Am I right? or wrong?
           * (hopefully, comparison at object level runs faster than char level)
          // two String objects are newly created and compared on char sequence basis
          if ( sb.toString().contentEquals(sb1.toString())){
               System.out.println("equal value");
          // two String objects are newly created and compared on object basis
          if ( sb.toString().equals(sb1.toString())){
               System.out.println("equal value");
           * Overall, the following is the best practice to do the comparison because of
           * reducing intermediate string object to one can improve performance
           * Am I right? or wrong?
          // one String object is newly created and compared against StringBuilder object
          // on char sequence basis
          if (sb.toString().contentEquals(sb1)){
               System.out.println("equal value");
}

Answer 1

Jay-K wrote:
Do you mean sb.toString().equals(sb1.toString)?
Because due to API specification, sb.equals() method is used to compare reference objects not the actual value of sb.Yes - you are right and my suggestion was rubbish.
The comment was about the two string versions. "sb.toString().equals(sb1.toString())" and "sb.toString().contentEquals(sb1.toString())" just do the same thing as far as I can see. These were your first two versions.
>
My question is if these two methods are the same, then why would we need duplicate methods in Java. The only difference that I can think of is the performance issue. Which is what motivated my question.The reason for a contentEquals() as well as an equals() for String seems to be so that you can write code like your third version. Basically contentEquals() is a method that deliberately allows for strings to be compared with (and be regarded as equal to) things that are not strings.