What is backslash in java

What are escape sequences in Java?

Many candidates are rejected or down-leveled in technical interviews due to poor performance in behavioral or cultural fit interviews. Ace your interviews with this free course, where you will practice confidently tackling behavioral interview questions.

Escape sequences are used to signal an alternative interpretation of a series of characters. In Java, a character preceded by a backslash (\) is an escape sequence.

The Java compiler takes an escape sequence as one single character that has a special meaning.

Common escape sequences

Below are some commonly used escape sequences in Java.

\t : Inserts a tab

This sequence inserts a tab in the text where it’s used.

\n : Inserts a new line

This sequence inserts a new line in the text where it’s used.

\r : Inserts a carriage return

This sequence inserts a carriage return in the text where it’s used. It’s expected to move the cursor back to the beginning of the line without moving down the line.

Note: Its output depends on the console being used. You may see the cursor moving down the line, or not moving at all.

\’ : Inserts a single quote

This sequence inserts a single quote character in the text where it’s used.

\» : Inserts a double quote

This sequence inserts a double quote character in the text where it’s used.

\\ : Inserts a backslash

This sequence inserts a backslash character in the text where it’s used.

Implementation

In the example below, the above escape sequences are shown in action:

class EscapeSequences
 
 
public static void main( String args[] )
 
 
// Add a tab between Edpresso and shot
 
System.out.println( "Edpresso\tshot" );
 
// Add a new line after Edpresso
 
System.out.println( "Edpresso\nshot" );
 
// Add a carriage return after Edpresso
 
System.out.println( "Edpresso\rshot" );
 
// Add a single quote between Edpresso and shot
 
System.out.println( "Edpresso\'shot" );
 
// Add a double quote between Edpresso and shot
 
System.out.println( "Edpresso\"shot" );
 
// Add a backslash between Edpresso and shot
 
System.out.println( "Edpresso\\shot" );
 
>
>

Every output matches the description provided above, except one. The expected result in the case of a \r sequence is:

Learn in-demand tech skills in half the time

Источник

Backslash Character in Java

Escape characters or escape sequences play an important role in Java when it comes to formatting strings, and the backslash character is what makes a character an escape character. In this article, we will discuss the Backslash character.

Use Backslash to Escape Characters in Java

In the example below, we use a backslash to perform different tasks.

Although a backslash can escape several characters like \t that inserts a tab, \b that puts a backspace where it is placed, or \r that is used for carriage return, but we talk about only three characters in the program.

The first string statement has the escape character \n , used to insert a new line where it is placed. The output shows that the escape sequence breaks the statement and puts on a new line, even if it is a single string.

In Java, we use double quotes to represent a string, but if we want to show or use double quotes in the string itself, we cannot do it without escaping the quotes. We enclose the string with the escape characters \» to escape the double-quotes.

The last string in the code below escapes the backslash itself, as it cannot be printed if a single backslash is used. This is why we use double backslashes.

public class JavaBackslash   public static void main(String[] args)   System.out.println("I am on the first line \nI am on the second line");  System.out.println("\"I am under double quotes because I am using a backslash to escape the double quotes.\"");  System.out.println("this\\is\\a\\path\\with\\escaped\\backslash");   > > 

I am on the first line I am on the second line "I am under double quotes because I am using a backslash to escape the double quotes." this\is\a\path\with\escaped\backslash 

Rupam Saini is an android developer, who also works sometimes as a web developer., He likes to read books and write about various things.

Related Article — Java Character

Источник

Characters

Most of the time, if you are using a single character value, you will use the primitive char type. For example:

char ch = 'a'; // Unicode for uppercase Greek omega character char uniChar = '\u03A9'; // an array of chars char[] charArray = < 'a', 'b', 'c', 'd', 'e' >;

There are times, however, when you need to use a char as an object—for example, as a method argument where an object is expected. The Java programming language provides a wrapper class that «wraps» the char in a Character object for this purpose. An object of type Character contains a single field, whose type is char . This Character class also offers a number of useful class (that is, static) methods for manipulating characters.

You can create a Character object with the Character constructor:

Character ch = new Character('a');

The Java compiler will also create a Character object for you under some circumstances. For example, if you pass a primitive char into a method that expects an object, the compiler automatically converts the char to a Character for you. This feature is called autoboxing—or unboxing, if the conversion goes the other way. For more information on autoboxing and unboxing, see Autoboxing and Unboxing.

Note: The Character class is immutable, so that once it is created, a Character object cannot be changed.

The following table lists some of the most useful methods in the Character class, but is not exhaustive. For a complete listing of all methods in this class (there are more than 50), refer to the java.lang.Character API specification.

Useful Methods in the Character Class

Method	Description
boolean isLetter(char ch) boolean isDigit(char ch)	Determines whether the specified char value is a letter or a digit, respectively.
boolean isWhitespace(char ch)	Determines whether the specified char value is white space.
boolean isUpperCase(char ch) boolean isLowerCase(char ch)	Determines whether the specified char value is uppercase or lowercase, respectively.
char toUpperCase(char ch) char toLowerCase(char ch)	Returns the uppercase or lowercase form of the specified char value.
toString(char ch)	Returns a String object representing the specified character value — that is, a one-character string.

Escape Sequences

A character preceded by a backslash (\) is an escape sequence and has special meaning to the compiler. The following table shows the Java escape sequences:

Escape Sequences

Escape Sequence	Description
\t	Insert a tab in the text at this point.
\b	Insert a backspace in the text at this point.
\n	Insert a newline in the text at this point.
\r	Insert a carriage return in the text at this point.
\f	Insert a form feed in the text at this point.
\’	Insert a single quote character in the text at this point.
\»	Insert a double quote character in the text at this point.
\\	Insert a backslash character in the text at this point.

When an escape sequence is encountered in a print statement, the compiler interprets it accordingly. For example, if you want to put quotes within quotes you must use the escape sequence, \», on the interior quotes. To print the sentence

System.out.println("She said \"Hello!\" to me.");

Источник

Escape Sequences in Java

A character with a backslash (\) just before it is an escape sequence or escape character. We use escape characters to perform some specific task. The total number of escape sequences or escape characters in Java is 8. Each escape character is a valid character literal.
The list of Java escape sequences:

Why will we need Escape sequence?
Suppose we would like to run the subsequent java code:

This code gives a compile time error as :

prog.java:3: error: ')' expected System.out.println("Hi geek, welcome to "GeeksforGeeks"."); ^ prog.java:3: error: not a statement System.out.println("Hi geek, welcome to "GeeksforGeeks"."); ^ prog.java:3: error: ';' expected System.out.println("Hi geek, welcome to "GeeksforGeeks"."); ^ 3 errors

This happened because the compiler expects nothing but only strings inside the quotation mark but when the compiler found a quotation mark, it expects another quotation mark in the near future (the closing one) and between them, the string of text should be created. During this case, the quotation marks of the word “GeeksforGeeks” gets nested(inside another quotation marks). Once the compiler reaches here, the compiler gets confused. According to the rule, the quotation mark suggests the compiler for creating a string but the compiler was busy with doing that thing previously and the code gives us a compile-time error.

So we should provide proper instructions to the compiler about the quotation mark. i.e, when a quotation is used for creating a string(as a command) and when it is a character itself (the part of the output string).
Similar sorts of confusion arise with other characters also(like- backslashes(), single and double quotation mark (‘, ”)) and these also provide a compile-time error in every case. For Solving these sorts of issues we have to use the java character escaping.

Control Sequence:
A control sequence is nothing however the backslash(\) glued with a character (the character which has to be escaped) is called a control sequence.
Example:
\\ is a control sequence used for displaying a backslash as output.

so let’s use this concept in the previous java code to avoid the compile-time error:

Источник