Multiple choice technology web technology

What is the output of the following StringBuffer sb1 = new StringBuffer("Amit"); StringBuffer sb2= new StringBuffer("Amit"); String ss1 = "Amit"; System.out.println(sb1==sb2); System.out.println(sb1.equals(sb2)); System.out.println(sb1.equals(ss1)); System.out.println("Poddar".substring(3));

  1. false false false dar

  2. false true false Poddar

  3. Compiler Error

  4. true true false dar
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

StringBuffer does not override equals() so it uses Object's equals() which compares references. sb1 and sb2 are different objects, so sb1==sb2 returns false and sb1.equals(sb2) also returns false. StringBuffer cannot be compared with String using equals(). "Poddar".substring(3) extracts characters from index 3 to end, giving "dar".

AI explanation

To answer this question, let's go through each option one by one:

Option A) false false false dar - This option is incorrect. The output of the given code is not "false false false dar".

Option B) false true false Poddar - This option is incorrect. The output of the given code is not "false true false Poddar".

Option C) Compiler Error - This option is incorrect. There is no compiler error in the given code.

Option D) true true false dar - This option is incorrect. The output of the given code is not "true true false dar".

Now, let's analyze the code step by step:

StringBuffer sb1 = new StringBuffer("Amit");
StringBuffer sb2 = new StringBuffer("Amit");
String ss1 = "Amit";
System.out.println(sb1 == sb2);
System.out.println(sb1.equals(sb2));
System.out.println(sb1.equals(ss1));
System.out.println("Poddar".substring(3));

In the given code, sb1 and sb2 are StringBuffer objects with the value "Amit", and ss1 is a String object with the value "Amit".

  1. System.out.println(sb1 == sb2); - This statement compares the references of sb1 and sb2. Since they are two separate StringBuffer objects, the result is false.

  2. System.out.println(sb1.equals(sb2)); - This statement compares the contents of sb1 and sb2. The equals() method in the StringBuffer class is not overridden to compare the contents, so it compares the references. Since sb1 and sb2 are two separate objects, the result is false.

  3. System.out.println(sb1.equals(ss1)); - This statement compares the contents of sb1 and ss1. The equals() method in the StringBuffer class is not overridden to compare the contents, so it compares the references. Since sb1 is a StringBuffer object and ss1 is a String object, the result is false.

  4. System.out.println("Poddar".substring(3)); - This statement returns a substring of the string "Poddar" starting from index 3. The substring is "dar".

Therefore, the correct answer is option A) false false false dar.

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