Question 1

What will be the value of position after the following code is executed? int position;
String str = "The cow jumped over the moon.";
Position = str.indexOf("ov");

Accepted Answer

The indexOf method returns the index within the string of the first occurrence of the specified substring. In this case, "ov" first appears starting at index 15 (considering the first character of the string has index 0).

Question 2

If str is declared as: String str = "ABCDEFGHI";
What will be returned from the following statement?
Character.toLowerCase(str.charAt(5))

Accepted Answer

The `charAt(5)` method call on the string "ABCDEFGHI" returns the character at index 5 (0-based indexing), which is 'F'. The `Character.toLowerCase()` method then converts this character to lowercase, resulting in 'f'.

Question 3

What is the value of str after the following code has been executed? 
 String str;
String sourceStr = "Hey diddle, diddle, the cat
And the fiddle";
Str = sourceStr.substring(12,17);

Accepted Answer

The substring method extracts characters from index 12 to 16 (17 is exclusive), resulting in "diddl".

Question 4

In the following statement, what data type must recField be? str.getChars(5, 10, recField, 0);

Accepted Answer

The method getChars(int srcBegin, int srcEnd, char[] dst, int dstBegin) of the String class requires the destination array (where characters are copied) to be of type char[]. Hence, recField must be a char array (char[]).

Question 5

What will be displayed after the following code is executed? String str = "RSTUVWXYZ";
System.out.println(str.charAt(5));

Accepted Answer

The charAt method returns the character at a specific index in a string, starting from 0. Therefore, str.charAt(5) returns the character at index 5, which is 'W'.

Question 6

In the following code, how many times will the for loop execute? 
String str = "1,2,3,4,5,6,7,8,9");
String[ ] tokens = str.split(",");
For (String s : tokens)
System.out.println(s);

Accepted Answer

The for loop will execute 9 times, once for each element in the array created by splitting the string "1,2,3,4,5,6,7,8,9" at commas, resulting in 9 elements.

Question 7

What would be the results of executing the following code? 
StringBuilder str = new StringBuilder("Little Jack
Horner ");
Str)append("sat on the ");
Str)append("corner");

Accepted Answer

The code, despite the syntax errors in the append method calls (should be str.append instead of Str)append), is intended to demonstrate how a StringBuilder object can be used to append strings. The correct syntax would result in "Little Jack Horner sat on the corner" being the final value of str. Assuming the intent behind the question and correcting the syntax errors, option D is correct.

Question 8

In the following code, how many times will the for loop execute? 
String str = ("Ben and Jerry's ice cream is great.");
String[ ] tokens = str.split(" ");
For (String s : tokens)
System.out.println(s);

Accepted Answer

The for loop will execute 7 times because the string "Ben and Jerry's ice cream is great." will be split into 7 tokens ["Ben", "and", "Jerry's", "ice", "cream", "is", "great."] based on spaces.

Question 9

What will be displayed after the following code is executed? boolean matches;
String str1 = "The cow jumped over the moon.";
String str2 = "moon";
Matches = str1.endsWith(str1);
System.out.println(matches);

Accepted Answer

The code checks if `str1` ends with `str1` itself, which is always true, but due to a typo in the case of the variable `matches` (it should be lowercase at its declaration), the code will not compile as written. If corrected, it would print `true`, but given the options and the mistake, the intended logic suggests `false` would be expected, yet this is a misunderstanding based on the provided code and options.

Question 10

What will be displayed after the following code is executed? StringBuilder strb = new StringBuilder(12);
Strb.append("The cow ");
Strb.append("jumped over the ");
Strb.append("moon.");
System.out.println(strb);

Accepted Answer

The StringBuilder object `strb` is used to append several strings together without creating multiple string objects, resulting in the output "The cow jumped over the moon." without any line breaks or additional characters.

Question 11

What will be displayed after the following code is executed? 
String str = "abc456";
For (int i = 0; i < str.length(); i++)
{
Char chr = str.CharAt(i);
If (!Character.isLetter(chr))
System.out.print(Character.toUpperCase(chr));
}

Accepted Answer

The code checks each character in the string "abc456" to determine if it is not a letter. If it is not a letter (i.e., it is a digit in this case), it prints the character as it is because `Character.toUpperCase(chr)` has no effect on digits. Therefore, only "456" is printed.

Question 12

What are the tokens in the following code? String str = "123-456-7890";
String[ ] tokens = str.split("-");

Accepted Answer

The correct tokens after splitting the string "123-456-7890" by "-" are "123", "456", and "7890". The split method divides the string into parts based on the delimiter, which is "-" in this case, and each part becomes a token.

Question 13

What are the tokens in the following statement? StringTokenizer st = new StringTokenizer("9-14-2018", "-", true);

Accepted Answer

The StringTokenizer class in Java is used to break a string into tokens. The constructor used here, `StringTokenizer("9-14-2018", "-", true)`, specifies that the delimiter ("-") should be returned as a token as well. Therefore, the tokens are "9", "-", "14", "-", "2018".

Question 14

Which of the following statements will convert the string, str = "285" to an int?

Accepted Answer

The correct method to convert a string to an integer in Java is by using the parseInt method of the Integer class, as shown in option D: int x = Integer.parseInt(str);.

Question 15

What will be displayed after the following code is executed? String str1 = "The quick brown fox jumped over the lazy dog.";
String str2 = str1.substring(20, 26);
System.out.println(str2);

Accepted Answer

The substring method in Java is used to extract a portion of a string. The method call str1.substring(20, 26) extracts the characters from index 20 to 25 (since the end index is exclusive). In the given string, this corresponds to the substring "jumped".

Question 16

Given the following, which of the statements below is not true? str.insert(8, 32);

Accepted Answer

The correct syntax for the insert method in the StringBuilder class is `insert(index, data)` where `index` is the position at which the data should be inserted, and `data` is the content to insert. Therefore, the insert will start at position 8, not 32, making option B incorrect.

Question 17

What will be the value of matches after the following code is executed? boolean matches;
String[ ] productCodes = {"456HI345", "3456hj"};
Matches = productCodes[0].regionMatches(true, 1,
ProductCodes[1], 2, 3);

Accepted Answer

The `regionMatches` method compares a specific region inside a string with another region in another string. In this case, it compares 3 characters starting from index 1 of `productCodes[0]` with 3 characters starting from index 2 of `productCodes[1]`, ignoring case. The regions being compared are "56H" from `productCodes[0]` and "56h" from `productCodes[1]`. Since the comparison is case-insensitive (`true` as the first argument), the regions match, hence the result is `true`.

Question 18

Which of the following statements will convert the string, str = "285.74" to a double?

Accepted Answer

Option B is correct because Double.parseDouble(String s) is the correct method to convert a String to a double in Java.

Question 19

What will be the value of position after the following code is executed?
 int position;
String str = "The cow jumped over the moon.";
Position = str.lastIndexOf("ov", 14);

Accepted Answer

The `lastIndexOf(String str, int fromIndex)` method searches for the last occurrence of a substring within the given string, starting the search at the specified index and moving backwards. It returns the index of the last occurrence of the substring or -1 if the substring is not found. In this case, the method is searching for "ov" starting from index 14 and moving backwards. Since "ov" occurs after index 14 in the string "The cow jumped over the moon.", it cannot be found when searching backwards from index 14, resulting in a return value of -1.

Question 20

Which of the following statements will print the maximum value an int variable may have?

Accepted Answer

The correct way to print the maximum value an int variable can have in Java is by using the wrapper class Integer and accessing its static field MAX_VALUE, as shown in option C: System.out.println(Integer.MAX_VALUE).

Quiz 9: Text Processing and More About Wrapper Classes

What will be the value of position after the following code is executed? int position; String str = "The cow jumped over the moon."; Position = str.indexOf("ov") ;

If str is declared as: String str = "ABCDEFGHI"; What will be returned from the following statement? Character.toLowerCase(str.charAt(5) )

What is the value of str after the following code has been executed? String str; String sourceStr = "Hey diddle, diddle, the cat And the fiddle"; Str = sourceStr.substring(12,17) ;

In the following statement, what data type must recField be? str.getChars(5, 10, recField, 0) ;

What will be displayed after the following code is executed? String str = "RSTUVWXYZ"; System.out.println(str.charAt(5) ) ;

In the following code, how many times will the for loop execute? String str = "1,2,3,4,5,6,7,8,9") ; String[ ] tokens = str.split(",") ; For (String s : tokens) System.out.println(s) ;

What would be the results of executing the following code? StringBuilder str = new StringBuilder("Little Jack Horner ") ; Str) append("sat on the ") ; Str) append("corner") ;

In the following code, how many times will the for loop execute? String str = ("Ben and Jerry's ice cream is great.") ; String[ ] tokens = str.split(" ") ; For (String s : tokens) System.out.println(s) ;

What will be displayed after the following code is executed? boolean matches; String str1 = "The cow jumped over the moon."; String str2 = "moon"; Matches = str1.endsWith(str1) ; System.out.println(matches) ;

What will be displayed after the following code is executed? StringBuilder strb = new StringBuilder(12) ; Strb.append("The cow ") ; Strb.append("jumped over the ") ; Strb.append("moon.") ; System.out.println(strb) ;

What will be displayed after the following code is executed? String str = "abc456"; For (int i = 0; i < str.length() ; i++) { Char chr = str.CharAt(i) ; If (!Character.isLetter(chr) ) System.out.print(Character.toUpperCase(chr) ) ; }

What are the tokens in the following code? String str = "123-456-7890"; String[ ] tokens = str.split("-") ;

What are the tokens in the following statement? StringTokenizer st = new StringTokenizer("9-14-2018", "-", true) ;

Which of the following statements will convert the string, str = "285" to an int?

What will be displayed after the following code is executed? String str1 = "The quick brown fox jumped over the lazy dog."; String str2 = str1.substring(20, 26) ; System.out.println(str2) ;

Given the following, which of the statements below is not true? str.insert(8, 32) ;

What will be the value of matches after the following code is executed? boolean matches; String[ ] productCodes = {"456HI345", "3456hj"}; Matches = productCodes[0].regionMatches(true, 1, ProductCodes[1], 2, 3) ;

Which of the following statements will convert the string, str = "285.74" to a double?

What will be the value of position after the following code is executed? int position; String str = "The cow jumped over the moon."; Position = str.lastIndexOf("ov", 14) ;

Which of the following statements will print the maximum value an int variable may have?