Java String and IO

The keyword “out” is the object of System class.

The ^ operator is used for <span style="font-family:" arial;="" font-size:="" small;="">representing<span style="font-family:" arial;="" font-size:="" small;=""> the XOR operator in Java.

The given statement creates 2 objects. The first object is refereed to by “str” and the second by the last string “Aliens”.

The method str.delete() deletes the characters in the string in the sequence 2 to 6. Hence, the output will be “I student”.

The size of an array cannot grow or shrink but the size of a vector can grow or shrink.

The number of elements in the vector represents the size of the vector and the maximum number of elements stored in the vector is the capacity of the vector that is 10 in this case.

The toCharArray() method is used to convert a given string to a new character array. Its return type is character array.
Syntax:
char[] toCharArray();

The ready() method is used to check whether the stream is ready to read.

Here, the output will be -1 because the ASCII difference of unmatched characters in “Rakesh” and “Roshan” is negative.

The steps to read a character are as follows.
char ch;
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
ch=(char)br.read();

The index of character ‘e’ is 3 because the index is starting from 0. The character at position 5 is ‘h'.

The readLine() method can be accessed by the object of a BufferedReader class. For example, 
String str;
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
str=br.readLine();

The correct syntax of the replace() method is
StringBuffer replace(int s,int e,String str)
Replaces the characters in a substring of the given sequence with the given string 'str'.

The NumberFormat class belongs to java.text package. It has three methods that yield standard formats for numbers, currency values and percentage values.

Both the statements are correct. The methods valueOf() and toString() belong to String class. The valueOf() method is a static method, so it is always called by using the class name String and the method toString() is overridden in wrapper classes, such as Integer and Double.

There are 8 parameterized constructors defined for a Scanner class.

The constructor StringBuffer() of a StringBuffer class creates a StringBuffer with the capacity of 16 characters by default.

The class String is defined in the package java.lang.

Java does not support pointers due to security reasons.

The method equlaIgnoreCase() is used to compare the given string to another string by ignoring the case consideration. Hence, to compare str1 and str2, the statement will be as follows:
str1.equalsIgnorecase(str2);

The method indexOf() is used to get the index within the given string “str” at the first occurrence of the specified substring “str1”. Hence, the statement will be
str.indexOf(String str1);

All are valid statements except str1.equalsIgnoreCase() because at least one parameter is required of string type.

We can also use the printf() statement in Java like C language. The correct way to display using printf() method is
System.out.printf(“Hello”);

Object of the Scanner class are useful in breaking down the inputs from the user into tokens, and these tokens can be converted into individual basic data types.

The nextToken() is the method of a StringTokenizer() class, and ttype is the filed name.

The PushBackReader class is not directly derived from the Reader class.

Character Oriented Input Stream provides support for reading and writing 16-bit characters.

The LineNumberInputStream, DataInputStream, BufferedInputStream, and PushBackInputStream classes are derived from FilterInputStream class.

In Java, the inputs are always considered as string datatypes. 

The countTokens() method is used to calculate the number of times the tokenizer's nextToken method can be called before it generates an exception