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Display a Backslash in Text in a Java Program

By Stephen Bucaro

In computer programming, a letter or digit is called a character and a collection of letters or digits that make a phrase, sentence, or paragraph, is called a string. Within a string there may be special characters that are used to produce things like new lines, tabs, backspaces, and carriage returns (place cursor at start of line). A special character is prefixed by a backslash \ (for example \b for backspace).

Backslash in a string

So what if you want to display a backslash in a string? To indicate that you want to display a backslash, use a double backslash \\ (which is actually a special character iyself). Example code to display a backspace in a string in java is shown below.

import javax.swing.*;

public class displayBackslash 
{

   public static void main(String s[])
   {
      JFrame frame = new JFrame();
      frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
      frame.setSize(300,300);
      frame.setLocationRelativeTo(null);
      frame.setTitle("Display Backslash");

      JTextArea myText = new JTextArea("To compile use the path c:\\Program Files\\java\\jdk1.8.0_121\\bin\\javac");
      myText.setLineWrap(true);
      frame.add(myText);

      frame.setVisible(true);
   }
}

I generally hate it when people add a bunch of extra code to an example. It confuses things. But in this case I've included the javax.swing library and added code to create a JFrame and a JTextArea. If I didn't add this extra code, you would need to use the System.out.print command to output text, and I don't think that's an interesting or realistic way to learn Java programming. The important part of this code is the line:

JTextArea myText = new JTextArea("To display a backslash use \\.");

Which is the line that is responsible for the actual display of the text. You can modify the code to display your own text by editing the text "To display a backslash use \\.". Note that in Java and other programming languages, a string is contained within double quotation marks.

If you wanted to experiment further, you could leave the JTextArea initializer empty and instead declare a String variable, initialize it with your text, and then use the JTextArea.append method to display the text in the program window, as shown below.

String myName = "To display a backslash use \\.";
JTextArea myText = new JTextArea();
myText.append(myName);

Note that, although in Java, the names of primitive variable types, like int and char begin with lower-case letters, the String variable type is capitalized. That's because strings are actually objects, which makes them very powerful because they contain methods like .length() and getChars.

If you're a beginner, for this example, I recommend downloading and installing the Java Development Kit from Oracle's web site. Type the code into a text file using a basic text editor like Window's Notepad (Do not use a word processor because they insert formatting codes into the file), saving the file with the .java file extension. Then use a batch file to compile the program. The batch file needs to contain the path to the compiler and the path to the source file, an example of compile.bat is shown below.

c:\Program Files\java\jdk1.8.0_121\bin\javac c:\Users\Stephen\Desktop\program_name.java
pause

The pause command on the second line will cause the DOS shell to stay open until you press any key, allowing you to read any errors. If successful, the compiler will create an executable file with the .class file extension. Then use a batch file to run the program. The batch file needs to contain the start command, the name of the java program launcher, and the name of the compiled java class file (without the .class extension). An example of run.bat is shown below.