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Jordi Castilla
Asked: 2020-12-16 08:33:13 +0800 CST 2020-12-16 08:33:13 +0800 CST

How to remove a character typed by console in Java?

  • 772

Is there a way to remove a character typed by console with System.outor System.err?

For example if I have a process that loads for a while, simulate an animation with the 3 ellipses .... Something similar to this demo on fiddle .

int puntos = 0;
final String PUNTO = ".";
System.out.print("Conectando, espera");

while (condicionQueSeCumplaAlAcabarElProceso) {
    if (puntos < 3) {                       // comprobar cuantos puntos hay
        System.out.print(PUNTO);            // poner un punto
        puntos ++;                          // indicarlo
        try {
            Thread.sleep(1000);             // esperar 1 segundo
        } catch(InterruptedException ex) {
            Thread.currentThread().interrupt();
        }
    } else {
        // aqui hay que borrar los 3 puntos ¿como se hace?
        puntos = 0;                         // resetear
    }
}
java

2 Answers

  1. Best Answer

    What you are looking for is the character \bthat is the retrocesoor backspace.

    Using it to delete the three dots ...as your example, it would be:

    int puntos = 0;
final String PUNTO = ".";
System.out.print("Conectando, espera");

while (condicionQueSeCumplaAlAcabarElProceso) {
    if (puntos < 3) {                       // comprobar cuantos puntos hay
        System.out.print(PUNTO);            // poner un punto
        puntos ++;                          // indicarlo
        try {
            Thread.sleep(1000);             // esperar 1 segundo
        } catch(InterruptedException ex) {
            Thread.currentThread().interrupt();
        }
    } else {
        // aqui hay que borrar los 3 puntos ¿como se hace?
        puntos = 0;                         // resetear
        System.out.print('\b\b\b');
    }
}

    An example of how to use it with numbers to represent percentage would be:

    public static void main(String[] args) throws Exception {
    System.out.print("Progreso: ");
    for (int percentage = 0; percentage < 100; percentage++) {
        System.out.print(percentage + "%");
        Thread.sleep(1000); //Simulamos que algo tardado pasa acá
        int length = String.valueOf(percentage).length() + 1;
        while (length-- > 0) {
            System.out.print('\b');
        }
    }
    System.out.println("Proceso finalizado!");
}

    Important: The console must support the character \b. Some consoles (such as IDE consoles) do not support it by default.

    • 12

  2. This is an example of what you want, based on what our friend Gepser shares, it is important to use \bfor the removal of the " ." character:

            System.out.println("Inicia proceso.");
        System.out.print("Conectando, espera");
        int puntos = 0;
        final String PUNTO = ".";
        int counter = 0;
        while (counter < 100) {
            if (puntos < 3) {                       
                System.out.print(PUNTO);            
                puntos ++;                          
                try {
                    Thread.sleep(500);             
                } catch(InterruptedException ex) {
                    ex.printStackTrace();
                }
            } else {
                puntos = 0;                         
                System.out.print("\b\b\b   \b\b\b");
                System.out.flush();
            }
            counter++;
        }
        System.out.println("\nTermina proceso!");

    Print the points one by one and then delete them to start the sequence, demo attached here

    exit:

    Conectando, espera.
Conectando, espera..
Conectando, espera...
Conectando, espera.
Conectando, espera..
Conectando, espera...
...
...
...
Termina proceso!
    • 1