How does Java handle backspace terminal control characters?

The backspace terminal control character is a special character represented by "\b" notation. It is used to move the cursor backward one character. It belongs to Java escape characters, which are characters used with backslash (\) that have special meaning to the compiler. In this article, we will understand and see the actual implementation of ‘\b’ notation through a Java sample program.

Backspace terminal control character working

Two situations may occur when using this escape character. First, when we hardcode the backspace character into a string, and second, when we use the keyboard for input.

Speaking of the first case, Java itself does not handle the backspace terminal control character. It just writes the byte value of the character to the output stream and then it's up to the terminal or console to interpret it. Some terminals may remove the previous character, while others may display strange symbols, or a few may ignore it.

Let us understand the previous points through an example

Example

public class BackspaceExample {
   public static void main(String[] args) {
      System.out.println("Tutorialss\bPoint");
   }
}

Output 1

TutorialssPoint

However, when the above code is compiled and executed on VS Code, it produces the following results.

Output 2

TutorialsPoint

We can see that the two compilers produce different results. Thus, it is proven that the backspace terminal control character is interpreted according to the terminal it was compiled for.

When reading user input using the "Scanner" class or any other input method, Java treats the backspace character as a regular character. It does not automatically interpret it as a special operation. In other words, when using the backspace symbol, the console will display the backspace character as-is and the previous character will not be removed from the input.

Let us take an example where we will collect user input for better understand

Example

import java.util.Scanner;
public class Input {
   public static void main(String []args) {
      Scanner read = new Scanner(System.in);
      System.out.println("Enter a String: ");
      while(read.hasNext()) { // runs till the last character
         String st = read.nextLine();
         System.out.println("String value: " + st);
      }
   }
}

Output

Enter a String:
Shriansh\bKumar
String value: Shriansh\bKumar

As mentioned before, placing backspace characters into user input values ​​is not considered a special operation. We can see in the output that the "\b" character is printed as is. In the above code, we create an instance of the "Scanner" class and read and write the user-provided input using a while loop.

in conclusion

The conclusion of this article is that we cannot rely on the backspace terminal control character to remove any characters from a string in Java because the way it works may vary depending on the terminal or compiler. Additionally, Java treats the backspace character as a regular character when it comes to user input. If we want to remove characters from string in Java, we should use other methods like "substring", "replace" or "StringBuilder" and "StringBuffer".

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