{"id":1222,"date":"2021-10-23T17:46:29","date_gmt":"2021-10-23T17:46:29","guid":{"rendered":"https:\/\/rahulshettyacademy.com\/blog\/index.php\/2021\/10\/23\/sdet-interview-questions-part-2\/"},"modified":"2021-10-23T17:46:29","modified_gmt":"2021-10-23T17:46:29","slug":"sdet-interview-questions-part-2","status":"publish","type":"post","link":"https:\/\/rahulshettyacademy.com\/blog\/index.php\/2021\/10\/23\/sdet-interview-questions-part-2\/","title":{"rendered":"Top SDET Interview Questions in Java – Part 2"},"content":{"rendered":"

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table of contents<\/div>\n<\/p><\/div>\n<\/div>\n<\/div>\n

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1. How to make class read-only explain briefly?<\/a><\/div>\n

2. What is Object Class explain?<\/a><\/div>\n

3. What is the difference between Mutable and Immutable Object? Explain String and StringBuilder in the same context<\/a><\/div>\n

4. What are the different types of exceptions in java?<\/a><\/div>\n

5. Can we have a Single Catch Block and Multiple Try block?<\/a><\/div>\n

6. Can we have try block without catch block? How do you handle multiple exception with single try block?<\/a><\/div>\n

7. Tell me the difference between == and .equals<\/a><\/div>\n

8. Tell me some helpful string methods in Java<\/a><\/div>\n

9. Why should avoid static methods in Java? Explain<\/a><\/div>\n

10. How can I use the thread concept in Java, Explain two types<\/a><\/div>\n

Course Alert<\/a><\/div>\n<\/div>\n

<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n

1. How to make class read-only explain briefly?<\/a><\/h3>\n
Java provides access modifiers such as private, public, protected, etc, The read-only class is where you can get the values of class members however you are not allowed to set values.<\/p>\n
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\n<\/ins>\n<\/div>\n
Simply, you are providing only the get method and not providing any set method<\/p>\n
Example Code Snippet<\/strong><\/p>\n<\/div>\n
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<\/div>\n
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\/\/Read-only class in Java<\/span><\/p>\n
\u00a0public class Fruit{<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0 private String fruitName= “Apple”;<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0 public String getFruitName() {<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 return fruitName;<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0 }<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0 public static void main(String[] args) {<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 Fruit f = new Fruit();<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 String result = f.getFruitName();<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 System.out.println(“Name of the Fruit:” + ” ” + result);<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0 }<\/span><\/p>\n
\u00a0}<\/span><\/p>\n<\/div>\n<\/div>\n<\/div>\n
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2. What is Object Class explain?<\/a><\/h3>\n
\n
Object class is the parent of all classes by default, This is the root class.<\/li>\n
Every class has Object as a superclass<\/li>\n
Object class is part of java.lang package<\/li>\n
You can assign Object of any type to Object class (Ex: Object obj = new Fruit();)<\/li>\n<\/ul>\n
Some useful methods provided by Object Class<\/strong><\/p>\n
toString():<\/strong> returns the string representation of this object.<\/p>\n
getClass():<\/strong> returns the Class class object of this object<\/p>\n
equals(Object obj):<\/strong> compares the given object to this object.<\/p>\n
finalize():<\/strong>\u00a0 this is invoked by the garbage collector before the object is being garbage collected.<\/p>\n
3. What is the difference between Mutable and Immutable Object? Explain String and StringBuilder in the same context<\/a><\/h3>\n
A mutable object can be changed after it’s created. An immutable object can’t change.<\/p>\n
Mutable objects provide a method to change the content of the object. The immutable objects do not provide any method to change the values<\/p>\n
Considering String and StringBuilder<\/p>\n
When you alter the values of String new object is formed so String is immutable<\/p>\n
If you alter the values in StringBuidler no new object is formed so StringBuilder is mutable \u00a0\u00a0<\/p>\n
Example Code Snippet : String is Immutable<\/strong><\/p>\n<\/div>\n
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<\/div>\n
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public class ImmutableString{\u00a0<\/span><\/p>\n
\u00a0public static void main(String args[]){\u00a0<\/span><\/p>\n
\u00a0\u00a0 String s=”Some text” ;<\/span><\/p>\n
\u00a0\u00a0 s.concat(“Another Text”);<\/span><\/p>\n
\u00a0\u00a0 System.out.println(s);\u00a0<\/span><\/p>\n
\u00a0}\u00a0<\/span><\/p>\n
}\u00a0<\/span><\/p>\n
<\/strong><\/span><\/p>\n
<\/strong><\/span><\/p>\n
Output:<\/span><\/span><\/strong><\/p>\n
Sometext<\/span><\/p>\n<\/div>\n<\/div>\n<\/div>\n
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Example Code Snippet : StringBuilder is mutable<\/strong><\/p>\n<\/div>\n
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<\/div>\n
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public class MutableString<\/span><\/p>\n
{<\/span><\/p>\n
\u00a0\u00a0\u00a0 public static void main (String[] args)<\/span><\/p>\n
\u00a0\u00a0\u00a0 {<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 StringBuffer str1 = new StringBuffer(“Java”);<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 StringBuilder str2 = new StringBuilder(“Demo”);<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 System.out.println(“Value of str1 before change :” + str1);<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 System.out.println(“Value of str2 before change :” + str2);<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 str1.append(” Some text”);<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 str2.append(” Another text”);<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 System.out.println(“Value of str1 after change :” + str1);<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 System.out.println(“Value of str2 after change :” + str2);<\/span><\/p>\n
\u00a0\u00a0\u00a0 }<\/span><\/p>\n
}<\/span><\/p>\n

<\/span><\/p>\n
Output:<\/span><\/strong><\/span><\/p>\n
Value of str1 before change :Java<\/span><\/p>\n
Value of str2 before change :Demo<\/span><\/p>\n
Value of str1 after change :JavaSome text<\/span><\/p>\n
Value of str2 after change :DemoAnother text<\/span><\/p>\n<\/div>\n<\/div>\n<\/div>\n
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4. What are the different types of exceptions in java?<\/a><\/h3>\n
Java Exceptions are broadly categorized into Checked<\/strong> and Un Checked<\/strong> exceptions.<\/p>\n
Checked exceptions are checked during compile time, Unchecked exceptions are thrown during run time.<\/p>\n
Consider if you are using eclipse IDE, checked exceptions are shown instantly inside your IDE, however, Unchecked exceptions are thrown only when you execute the program<\/p>\n
Example of Checked Exception: Eclipse IDE <\/strong>(For your Reference Only)<\/p>\n
$\"\"$ <\/p>\n
Example : Unchecked Exception<\/strong><\/p>\n<\/div>\n
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public class UnCheckedException<\/span><\/p>\n
{<\/span><\/p>\n
\u00a0\u00a0\u00a0 public static void main (String[] args)<\/span><\/p>\n
\u00a0\u00a0\u00a0 {<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0 int a=10;<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0 int b = a\/0;<\/span><\/p>\n
\u00a0\u00a0\u00a0 }<\/span><\/p>\n
}<\/span><\/p>\n
Output:<\/span><\/span><\/strong><\/p>\n
Exception in thread “main” java.lang.ArithmeticException<\/u>: \/ by zero<\/span><\/p>\n
\u00a0\u00a0 at UnCheckedException.main(UnCheckedException.java:6<\/u>)<\/span><\/p>\n<\/div>\n<\/div>\n<\/div>\n
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5. Can we have a Single Catch Block and Multiple Try block?<\/a><\/h3>\n
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We can have single or multiple catch blocks associated with the try block<\/li>\n
We cannot have multiple try blocks, there can be only one try block before catch\/finally block<\/li>\n
You can have try block inside try block followed by the catch block<\/li>\n<\/ul>\n
Important!: Below code doesn\u2019t Execute<\/strong><\/p>\n
<\/strong><\/p>\n
Example : Multiple try block at the same level<\/strong><\/p>\n<\/div>\n
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<\/div>\n
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\/\/INVALID, this throws Error<\/span><\/p>\n
public class TryCatchExample {<\/span><\/p>\n
\u00a0\u00a0\u00a0 public static void main(String[] args) {<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 try {<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 int a = 10;<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 int b = a \/ 0;<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 }<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 try {<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 }<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 catch (ArithmeticException e) {<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 }<\/span><\/p>\n
\u00a0\u00a0\u00a0 }<\/span><\/p>\n
}<\/span><\/p>\n<\/div>\n<\/div>\n<\/div>\n
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Example : try inside try block, Below code is correct example, Try inside try block is valid<\/strong><\/p>\n<\/div>\n
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<\/div>\n
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\/\/Completely Valid Example try insdie try block<\/span><\/p>\n
public class TryCatchExample {<\/span><\/p>\n
\u00a0\u00a0\u00a0 public static void main(String[] args) {<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 try {<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 try { \/\/nested try<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 int a = 10;<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 int b = a \/ 0;<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 } catch (Exception e) {<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 }<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 }<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 catch (ArithmeticException e) {<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 }<\/span><\/p>\n
\u00a0\u00a0\u00a0 }<\/span><\/p>\n
}<\/span><\/p>\n<\/div>\n<\/div>\n<\/div>\n
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6. Can we have try block without catch block? How do you handle multiple exception with single try block?<\/a><\/h3>\n
Yes, we can have try block without catch block, in that case we need to have finally block associated with try block.<\/p>\n
Example Code Snippet : try without catch block and having finally block<\/strong><\/p>\n<\/div>\n
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<\/div>\n
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\/\/Completely Valid Example try without catch but with finally<\/span><\/p>\n
public class TryCatchFinallyExample {<\/span><\/p>\n
\u00a0\u00a0\u00a0 public static void main(String[] args) {<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 try {<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 int a = 10;<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 int b = a \/ 0;<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 }<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 finally {<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 System.out.println(“Finally Executed”);<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 }<\/span><\/p>\n
\u00a0\u00a0\u00a0 }<\/span><\/p>\n
}<\/span><\/p>\n<\/div>\n<\/div>\n<\/div>\n
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Example Code Snippet : Multiple Exception can be handled with multiple catch block, and single try block<\/strong><\/p>\n<\/div>\n
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<\/div>\n
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public class MultipleExceptionHandling {<\/span><\/p>\n
\u00a0\u00a0\u00a0 public static void main(String[] args) {<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 try {<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 int a[] = new int[15];<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 a[15] = 99 \/ 0;<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 } catch (ArithmeticException e) {<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 System.out.println(“Arithmetic Exception”);<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 } catch (ArrayIndexOutOfBoundsException e) {<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 System.out.println(“ArrayIndexOutOfBounds Exception”);<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 } catch (Exception e) {<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 System.out.println(“Parent Exception”);<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 }<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 System.out.println(“Prints at the end”);<\/span><\/p>\n
\u00a0\u00a0\u00a0 }<\/span><\/p>\n
}<\/span><\/p>\n
Output:<\/span><\/strong><\/p>\n
Arithmetic Exception<\/span><\/p>\n
Prints at the end<\/span><\/p>\n<\/div>\n<\/div>\n<\/div>\n
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7. Tell me the difference between == and .equals<\/a><\/h3>\n
==<\/strong> is operator and .equals<\/strong> is method<\/p>\n
==<\/strong> is used for comparison for memory address. .equals<\/strong> is used for competition of value<\/p>\n
<\/strong><\/p>\n
Example Code Snippet<\/strong><\/p>\n<\/div>\n
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<\/div>\n
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public class Demo{<\/span><\/p>\n
\u00a0\u00a0\u00a0 public static void main(String[] args)<\/span><\/p>\n
\u00a0\u00a0\u00a0 {<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 String s1 = “Test”;<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 String s2 = “Test”;<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 String s3 = new String(“Test”);<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 System.out.println(s1 == s2); \/\/ prints true<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 System.out.println(s1 == s3); \/\/ prints false<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 System.out.println(s1.equals(s2)); \/\/ prints true<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 System.out.println(s1.equals(s3)); \/\/ prints true<\/span><\/p>\n
\u00a0\u00a0\u00a0 }<\/span><\/p>\n
}<\/span><\/p>\n<\/div>\n<\/div>\n<\/div>\n
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8. Tell me some helpful string methods in Java<\/a><\/h3>\n
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charAt() :<\/strong> This method returns the character at the specified index (position)<\/li>\n<\/ul>\n
Example Code Snippet<\/strong><\/p>\n<\/div>\n
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<\/div>\n
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String string = “Academy”;<\/span><\/p>\n
char ch = string.charAt(1); \/\/ Returns c<\/span><\/p>\n<\/div>\n<\/div>\n<\/div>\n
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concat():<\/strong> Appends a string to the end of another string<\/li>\n<\/ul>\n
Example Code Snippet<\/strong><\/p>\n<\/div>\n
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<\/div>\n
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String string1 = “Rahul Shetty”;<\/span><\/p>\n
String string2 = ” Academy”;<\/span><\/p>\n
String str = string1.concat(string2); \/\/Returns Rahul Shetty Academy<\/span><\/p>\n<\/div>\n<\/div>\n<\/div>\n
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contains():<\/strong> Checks whether a string contains a sequence of characters<\/li>\n<\/ul>\n
Example Code Snippet<\/strong><\/p>\n<\/div>\n
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String string2 = ” Academy”;<\/span><\/p>\n
boolean bool = string2.contains(“my”); \/\/Returns true<\/span><\/p>\n<\/div>\n<\/div>\n<\/div>\n
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equals():<\/strong> Compares two strings. Returns true if the strings are equal, and false if not<\/li>\n<\/ul>\n
Example Code Snippet<\/strong><\/p>\n<\/div>\n
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String string1 = “Tiger”;<\/span><\/p>\n
String string2 = “Tiger”;<\/span><\/p>\n
boolean bool = string1.equals(string2);\/\/Returns true<\/span><\/p>\n<\/div>\n<\/div>\n<\/div>\n
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equalsIgnoreCase()<\/strong><\/a> : <\/strong>Compares two strings, ignoring case considerations<\/li>\n<\/ul>\n
Example Code Snippet<\/strong><\/p>\n<\/div>\n
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String string1 = “TiGer”;<\/span><\/p>\n
String string2 = “TigeR”;<\/span><\/p>\n
boolean bool = string1.equalsIgnoreCase(string2);\/\/Returns true<\/span><\/p>\n<\/div>\n<\/div>\n<\/div>\n
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indexOf():<\/strong> Returns the position of the first found occurrence of specified characters in a string<\/li>\n<\/ul>\n
Example Code Snippet<\/strong><\/p>\n<\/div>\n
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String string2 = “Academy”;<\/span><\/p>\n
int index = string2.indexOf(“my”); \/\/Returns 5<\/span><\/p>\n<\/div>\n<\/div>\n<\/div>\n
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length():<\/strong> Returns the length of a specified string<\/li>\n<\/ul>\n
Example Code Snippet<\/strong><\/p>\n<\/div>\n
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String string = “Academy”;<\/span><\/p>\n
int l = string.length(); \/\/Returns 7<\/span><\/p>\n<\/div>\n<\/div>\n<\/div>\n
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isEmpty():<\/strong> Checks whether a string is empty or not<\/li>\n<\/ul>\n
Example Code Snippet<\/strong><\/p>\n<\/div>\n
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String string = “”;<\/span><\/p>\n
boolean isEmpty = string.isEmpty(); \/\/Returns true<\/span><\/p>\n<\/div>\n<\/div>\n<\/div>\n
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replace(): <\/strong>Searches a string for a specified value, and returns a new string where the specified values are replaced<\/li>\n<\/ul>\n
Example Code Snippet<\/strong><\/p>\n<\/div>\n
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<\/div>\n
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String string = “Academy”;<\/span><\/p>\n
String newString = string.replace(“my”,”-replacetest”); \/\/Returns Acade-replacetest<\/span><\/p>\n<\/div>\n<\/div>\n<\/div>\n
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replaceAll():<\/strong> Replaces each substring of this string that matches the given regular expression with the given replacement<\/li>\n<\/ul>\n
Example Code Snippet<\/strong><\/p>\n<\/div>\n
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String string = “academy”;<\/span><\/p>\n
String newString = string.replace(“a”,”O”); \/\/Returns OcOdemy<\/span><\/p>\n<\/div>\n<\/div>\n<\/div>\n
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replaceFirst():<\/strong> Replaces the first occurrence of a substring that matches the given regular expression with the given replacement<\/li>\n<\/ul>\n
Example Code Snippet<\/strong><\/p>\n<\/div>\n
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<\/div>\n
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String string = “academy”;<\/span><\/p>\n
String newString = string.replaceFirst(“a”,”O”); \/\/Returns Ocademy<\/span><\/p>\n<\/div>\n<\/div>\n<\/div>\n
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split():<\/strong> Splits a string into an array of substrings<\/li>\n<\/ul>\n
Example Code Snippet<\/strong><\/p>\n<\/div>\n
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<\/div>\n
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String string = “Rahul Shetty Academy”;<\/span><\/p>\n
String[] newString = string.split(” “);<\/span><\/p>\n
\/\/ newString will have values like [Rahul, Shetty, Academy]<\/span><\/p>\n<\/div>\n<\/div>\n<\/div>\n
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substring():<\/strong> Returns a new string which is the substring of a specified string<\/li>\n<\/ul>\n
Example Code Snippet<\/strong><\/p>\n<\/div>\n
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<\/div>\n
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String string = “Rahul Shetty Academy”;<\/span><\/p>\n
String newString = string.substring(0,3); \/\/ Returns Rah<\/span><\/p>\n<\/div>\n<\/div>\n<\/div>\n
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toCharArray():<\/strong> Converts this string to a new character array<\/li>\n<\/ul>\n
Example Code Snippet<\/strong><\/p>\n<\/div>\n
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<\/div>\n
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String string = “Academy”;<\/span><\/p>\n
char[] charArray = string.toCharArray();<\/span><\/p>\n
\/\/charArray will have values like [‘A’,’c’,’a’,’d’,’e’,’m’,’y’] \u00a0 \u00a0 <\/span><\/p>\n<\/div>\n<\/div>\n<\/div>\n
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toLowerCase() :<\/strong> Converts a string to lower case letters<\/li>\n<\/ul>\n
Example Code Snippet<\/strong><\/p>\n<\/div>\n
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<\/div>\n
\n
\n
String string = “AcAdEmY”;<\/span><\/p>\n
String newString = string.toLowerCase(); \/\/ Returns academy<\/span><\/p>\n<\/div>\n<\/div>\n<\/div>\n
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toUpperCase() :<\/strong> Converts a string to upper case letters<\/li>\n<\/ul>\n
Example Code Snippet<\/strong><\/p>\n<\/div>\n
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<\/div>\n
\n
\n
String string = “AcAdEmY”;<\/span><\/p>\n
String newString = string.toUpperCase(); \/\/ Returns ACADEMY<\/span><\/p>\n<\/div>\n<\/div>\n<\/div>\n
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trim():<\/strong> Removes whitespace from both ends of a string<\/li>\n<\/ul>\n
Example Code Snippet<\/strong><\/p>\n<\/div>\n
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<\/div>\n
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String string = ” \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 Academy \u00a0 \u00a0 \u00a0 “;<\/span><\/p>\n
String newString = string.trim(); \/\/ Returns Academy<\/span><\/p>\n<\/div>\n<\/div>\n<\/div>\n
\n
9. Why should avoid static methods in Java? Explain<\/a><\/h3>\n
A static method can be choose based on the requirement, as static method comes with its pros and cons.<\/p>\n
A static method belongs to class not to instance<\/p>\n
A static method cannot be overridden<\/p>\n
A non-static method cannot be called inside a static method<\/p>\n
A static method cannot refer to \u201cthis\u201d or \u201csuper\u201d keywords in any way<\/p>\n
Considering above, with the static method we cannot fully utilize the Object-Oriented Feature, so it is good practice to avoid static methods, however, there might be cases we might need to use the static method intentionally then we can go for the static method.<\/p>\n
10. How can I use the thread concept in Java, Explain two types<\/a><\/h3>\n
Threads can be implemented using two ways in Java,<\/p>\n
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Extending Thread class<\/li>\n
Implementing Runnable interface<\/li>\n<\/ul>\n
Example Code Snippet: Extending Thread class<\/strong><\/p>\n<\/div>\n
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<\/div>\n
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public class Multi extends Thread {<\/span><\/p>\n
\u00a0\u00a0\u00a0 public void run() {<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 System.out.println(“Started…”);<\/span><\/p>\n
\u00a0\u00a0\u00a0 }<\/span><\/p>\n
\u00a0\u00a0\u00a0 public static void main(String args[]) {<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 Multi t1 = new Multi();<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 t1.start();<\/span><\/p>\n
\u00a0\u00a0\u00a0 }<\/span><\/p>\n
}<\/span><\/p>\n<\/div>\n<\/div>\n<\/div>\n
\n
Example Code Snippet: Implementing Runnable interface<\/strong><\/p>\n<\/div>\n
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<\/div>\n
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public class MultiT implements Runnable {<\/span><\/p>\n
\u00a0\u00a0\u00a0 public void run() {<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 System.out.println(“Started…”);<\/span><\/p>\n
\u00a0\u00a0\u00a0 }<\/span><\/p>\n
\u00a0\u00a0\u00a0 public static void main(String args[]) {<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 MultiT m1 = new MultiT();<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 Thread t1 = new Thread(m1);<\/span><\/p>\n
\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 t1.start();<\/span><\/p>\n
\u00a0\u00a0\u00a0 }<\/span><\/p>\n
}<\/span><\/p>\n<\/div>\n<\/div>\n<\/div>\n
\n
Note: <\/strong>In the above example, we are implementing a Runnable interface so, Class object is not treated as a thread, we need to create the Thread class explicitly passing the class object as a parameter to the constructor.<\/em><\/p>\n<\/div>\n
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Course Alert<\/span><\/em><\/h5>\n
If you are interested in landing a SDET or Sr. QA Automation Engineer role, check out our popular SDET course to learn the fundamental skills required an SDET needs to perform at work. Also, I have another popular course which covers Top 150+ Interview questions most commonly asked in SDET \/ Automation interviews.<\/strong><\/p>\n<\/div>\n
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SDET\/Test Architect Essentials -Road to Full stack QA<\/a><\/span><\/li>\n
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SDET\/QA Automation Interview Kit + Java logic Programs<\/a><\/span><\/li>\n<\/ul>\n<\/div>\n
\n
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<\/div>\n
\n
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A Quick Note<\/strong><\/em><\/h4>\n<\/div>\n\n
Please remember all these courses comes with 100% Lifetime acces<\/strong>s<\/strong> and free updates for Lifetime!!<\/strong><\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n
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Please click on the link\u00a0Sr.QA and SDET Interview Questions in Java \u2013 Part 3<\/span><\/a><\/em><\/strong> to continue to part-3 series of this article.<\/p>\n<\/div>\n<\/div>\n<\/div>\n
<\/div>\n<\/section>\n
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