Explanations “Top Java Quiz Questions”

What is the result of the following code?

public class Lion {
 public void roar(String roar1, StringBuilder roar2) {
 roar1.concat("!!!");
 roar2.append("!!!");
 }
public static void main(String[] args) {
 String roar1 = "roar";
 StringBuilder roar2 = new StringBuilder("roar");
 new Lion().roar(roar1, roar2);
 System.out.println(roar1 + " " + roar2);
} }

❌ A. roar roar
✅ B. roar roar!!!
❌ C. roar!!! roar
❌ D. roar!!! roar!!!
❌ E. An exception is thrown.
❌ F. The code does not compile.

Explanation:
A String is immutable. Calling concat() returns a new String but does not change the original. A StringBuilder is mutable. Calling append() adds characters to the existing character sequence along with returning a reference to the same object

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471 viewsMar 26, 2021 at 09:04

What is the result of the following code?

public class Lion {
 public void roar(String roar1, StringBuilder roar2) {
 roar1.concat("!!!");
 roar2.append("!!!");
 }
public static void main(String[] args) {
 String roar1 = "roar";
 StringBuilder roar2 = new StringBuilder("roar");
 new Lion().roar(roar1, roar2);
 System.out.println(roar1 + " " + roar2);
} }

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