Can you overwrite System.out.println ("") ;?

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Can you overwrite System.out.println ("") ;?

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#1 by (6 votes)

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I am in a project written in Java somewhat advanced where I have used a lot of messages by console. I would not like to remove them, but not to print them if I do not define it that way in any configuration option of the program (For example, run it in debug mode).

What I want is to direct them to my own "message console" where I can manipulate this information (Show on screen, create logs, etc). Currently I have a function that simulates the structure (A class that calls the console and have named the instance and a role as SystemOut.println() ) but I would like to overwrite System.out.println("") non modify the code that I have defined and also capture so immediately the exceptions. Is this possible? I am open to recommendations.

java

asked by Angel 31.07.2017 в 16:24

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1 answer

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score 6 · Accepted Answer

It is possible to change the PrintStream that the System class uses to write the messages. See the documentation System.setPrintStream ()

Example

PrintStream myStream = new PrintStream(System.out) {
    @Override
    public void println(String x) {
        super.println(System.currentTimeMillis() + ": " + x);
    }
};
System.setOut(myStream);
System.out.println("Hola mundo!");

Exit:

1420553422337: Hola mundo!

Redirect to a file

You can create the PrintStream to write directly to a file:

File file = new File("C:\a.txt");
PrintStream ps = new PrintStream(file);
System.setOut(ps);
System.out.println("To File");

And finally, the recommendation is to use a logger from the beginning of development, with that you have control with the form of logging (Change destination, level of detail, message format, etc.) without changing the code.