What we know about the "STRING"? MCQ on String for concepts and interview preparation QAE - SDET - AUTOMATION QA 2022

 

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Java Interview question Set-1: SET-01 1-10

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Java Interview question Set-3: SET-03 21-30

Here are the top 5 things to know about Java strings:

1. Strings are objects:
   In Java, strings are objects of the String class, which is included in the java.lang package. This means that strings have a wide range of methods available for manipulating and processing them.

2. Strings are immutable:
   In Java, strings are immutable, which means that once a string is created, it cannot be changed. Any operation that appears to modify a string actually creates a new string object. This has implications for memory usage and performance.

3. String literals:
   String literals are enclosed in double quotes (e.g. "hello"), and they are automatically created as String objects when the program is executed. String literals are also pooled, which means that if two string literals have the same value, they will be references to the same object.

4. String concatenation:
   Strings can be concatenated using the "+" operator or the concat() method. When concatenating strings in a loop or other performance-sensitive code, it is more efficient to use a StringBuilder or StringBuffer object, which can avoid creating many intermediate string objects.

5. String comparisons:
   Strings can be compared using the equals() method or the equalsIgnoreCase() method. The == operator can also be used to compare strings, but it checks for reference equality, not value equality. When comparing many strings in a performance-sensitive application, it can be more efficient to use the intern() method to intern the strings and compare their references.

1. What is the output for below?

String str1 = "test";
String str2 = "one";

String str3 = str1.concat(str2);

Ans:

a) testone

b) test

c) one

d) Let me check in IDE :)

2. What is the output for below?

String str1 = "test";
String str2 = "test";

String str3 = new String("test");

System.out.println(str1.equals(str2));

System.out.println(str1.equals(str3));

Ans:

a) true,true

b) false, true

c) false, false

d) Let me check in IDE :)

3. What is the output for below?

String str1 = "test";

String str2 = "test";

String str3 = new String("test");

System.out.println(str1==str2));

System.out.println(str1==str3);

a) true, true

b) true, false

c) false, true

d) false, false

4. What is the output for below?

String str = "test";

System.out.println(str1.charAt(2)); 

a) s

b) e

c) error

d) es

5. What is the output for below?

System.out.println("012301230123".replace(55, "45"));

 System.out.println("012301230123".replace("01", "45"));

a) compile error, 452345234523

b) 452345234523, 452345234523

c) error, error

d) Let me check in IDE :)

6. What is the output for below?

System.out.println("tes".substring(3));

System.out.println("test".substring(3));

a) error, error

b) error, t

c)  , t

d) t, t

7. How many ways we can create String Object in Java?

a) String s = "abc"; String s1 = new String("abc");

b) Literal, Keyword

c)  Both A and B

d)  Not sure

CLICK HERE FOR ANSWERS OF ALL QUESTIONS

8. Is String thread safe?

a) true

b) false

c) Not sure

9. What is the output for below?

String str8 = new StringBuilder("test").reverse().toString();

System.out.println(str8);

a) test

b) tset

c) Not sure

10. Which one is thread safe: StringBuffer or StringBuffer ?

a) Both

b) StringBuffer

c) StringBuilder

d) None of the options

Click below link for the answers of above 1-10 Question

CLICK HERE FOR ANSWERS OF ALL THE QUESTIONS

To go through all the string manipulation related interview Q&A, refer the link here: String Manipulation Interview Q&A

String Related Q&A

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These commands cover a range of basic UI interactions and are a good starting point for building automated tests with Cypress.

Do remember that knowing Linux is one of the most important aspect to work as an SDET.

Basic Linux Commands for Automation QA

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