How to Write Console Output to a Txt File

How to write console output to a txt file

You need to do something like this:

PrintStream out = new PrintStream(new FileOutputStream("output.txt"));
System.setOut(out);

The second statement is the key. It changes the value of the supposedly "final" System.out attribute to be the supplied PrintStream value.

There are analogous methods (setIn and setErr) for changing the standard input and error streams; refer to the java.lang.System javadocs for details.

A more general version of the above is this:

PrintStream out = new PrintStream(
        new FileOutputStream("output.txt", append), autoFlush);
System.setOut(out);

If append is true, the stream will append to an existing file instead of truncating it. If autoflush is true, the output buffer will be flushed whenever a byte array is written, one of the println methods is called, or a \n is written.

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I'd just like to add that it is usually a better idea to use a logging subsystem like Log4j, Logback or the standard Java java.util.logging subsystem. These offer fine-grained logging control via runtime configuration files, support for rolling log files, feeds to system logging, and so on.

Alternatively, if you are not "logging" then consider the following:

• With typical shells, you can redirecting standard output (or standard error) to a file on the command line; e.g.

  $ java MyApp > output.txt   
  

  For more information, refer to a shell tutorial or manual entry.

• You could change your application to use an out stream passed as a method parameter or via a singleton or dependency injection rather than writing to System.out.

Changing System.out may cause nasty surprises for other code in your JVM that is not expecting this to happen. (A properly designed Java library will avoid depending on System.out and System.err, but you could be unlucky.)

Print console output to text file

If you want to save all the print statements into a text file then, you can copy the things you want to save in the file and store them in a variable and then write them in the text file. For example, I edited your code to this:

import time
import sys

# variable declaration

user_cave = 0
cave = 0
result = ""
playagain = "Y"

while playagain == "Y" or playagain == "y":
    f = open("Dragon Game.txt", 'w')
    f.write("")
    print(
        "\nYou are in the Kingdom of Dragons.\nIn front of you, you see two caves.\nIn one cave, the dragon is friendly and will share his treasure with you.\nThe other dragon is hungry and will eat you on sight!\nGood luck on your journey\n")
    while True:  # including while true because program should till break

        try:  # repeat till user give correct value
            user_cave = int(input("Please select cave 1,2,3,4 or 5 : "))
            if user_cave > 0 and user_cave < 6:
                break

            else:
                continue

        except:
            ""

    # create random number to differentiate
    cave = random.randrange(1, 3)

    # Bad dragon
    if cave == 1:
        result = "Gobbles you down!"
    # Good Dragon
    elif cave == 2:
        result = "Greets you before share his treasure!"
    txt = f"\nYou are in the Kingdom of Dragons.\nIn front of you, you see two caves.\nIn one cave, the dragon is friendly and will share his treasure with you.\nThe other dragon is hungry and will eat you on sight!\nGood luck on your journey\nYou approach the cave....{str(user_cave)}\nA large dragon jumps out in front of you!\nHE OPENS HIS JAWS AND.....\n{result}"
    f = open("Dragon Game.txt", "a")
    f.write(txt)
    print("\nYou approach the cave.... " + str(user_cave))
    time.sleep(1.5)
    print("A large dragon jumps out in front of you!")
    time.sleep(1.5)
    print("HE OPENS HIS JAWS AND.....\n")
    time.sleep(2)
    print(result, "\n")

    playagain = input("Do you want to play again ? [y/n] : ")

Just, before running this file, you have to create a file named Dragon Game.txt It's compulsory to run the code.

Java: How to save console output to a text file?

System class provide you a way to dump output in different stream which is System#setOut(PrintStream out)

Using this method you can pass you FileInputstream to System.setOut and you can save the console output.

PrintStream printStream = new PrintStream(new FileOutputStream(file));
System.setOut(printStream);

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One interesting part of this question is though out is declared as final in System class but still you reassign this by System#setOut.

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