Java Strings

As I explained the reason all of the functions are defined in the String class. So this is correct answer.

This is the correct answer. Substring method takes two parameters (beginIndex,EndIndex).Substring( int Begin , int End). It return the string from begin to end – 1.But if the begin index is greater than the endindex, then a "IndexOutOfBoubd" exception will occur. So here substring(4,3) will give runtime error.So this is the correct answer.

This is the correct answer. The compiler will throw an error that method match() was not declared.Because String class do not contains any method named match().The correct method is matches(). So the above statement should be s.matches(s1).So this is the correct answer.

This is the correct answer. Because there is no method defined in the String class named toLower(). So it cannot be invoked using the object of String class.The correct method is toLowerCase() which converts the characters to lowercase.So this is correct answer according to the question asked.

This is the correct answer. The first two characters from s1 and s2 (a vs a) are compared, they are equal. Then (b vs b) are compared they are also equal. Now ( c vs g ) are compared. Since c is 4 less than g, so -4 is returned. So this is correct answer.

As explained that all of the methods given are defined in the character class. So this is the correct choice.

lastIndexOf(String s , index i) method return the last occurrence of string s before the from index. Return -1 if string not found. So here the string to find is “Java” before the index 5 which means before the character m.but string “java” is not present before the index 5 i.e character m.so it will return -1.So this is the correct answer.

This is the correct answer. S.length() wil return 15 because there are 15 characters in the String.So the code looks like this :-s.charAt(15);the index count starts at 0. In this way the last character a is at index number 14. So if we try to access a character in a string which is out of bound then a runtime exception “StringOutOfBound” will be thrown.So we can pass only till s.charAt(s.length()-1).So this is correct answer.

The correct answer is 16. When stringbuffer object is created the default capacity of the object is always 16.If the number of characters in the string increases the capacity will increase with the following formula:-2 * (previous capacity + 1)In this case hello has 5 characters so default capacity will not change.So this is correct answer.

As I explained that both 1 & 2 options are valid functions in java.So this is the correct answer.

This is the correct answer. Because the String class objects are immutable i.e once the object of the String class is created its contents cannot be changed.So we cannot append new characters or string in the old string.So this is the correct answer.

As I explained both char and string can be passed as the first parameter to the lastIndexOf() method.So this is the correct answer.

This is the correct answer. delete(int start , int end) delete the characters from the start index till end-1 index.So the welcome to java will delete the characters from 8 to 11 characters.So the resulting string remains “ Welcome ava”.Index starts from 0.So this is the correct answer.

This is the correct answer. Length() function return the number of characters in the string. As we can count that the number of characters in the given string are 15. So length() will return 15.charAt() function return the character at the given index in the parameter. Remember that the index count starts at 0.So charAt(0) is W , counting in this way we reach charAt(9) is o.So this is the correct answer.

This is the correct answer. Substring method takes two parameters (beginIndex,EndIndex).Substring( int Begin , int End). It return the string from begin to end – 1.But if the begin index is equal to the endindex then an empty String with length 0 will be returned. So here substring(4,4) will return an empty string of length 0.So this is the correct answer.