system.out | 易学教程

Intercept System.out and prepend date time in Java

阅读更多关于 Intercept System.out and prepend date time in Java

问题 is it possible to intercept calls to System.out.print* and System.err.print* (in Java) and prepend a time stamp to them? Don't worry, we use the usual logging frameworks, but occasionally some sys.out leaks out and it would be nice to know when it happen so we can tie it up to the proper log files. 回答1: You can do it. See the docs Reassigns the "standard" output stream. First, if there is a security manager, its checkPermission method is called with a RuntimePermission("setIO") permission to

Cause runtime exceptions to be properly ordered with println in console output

阅读更多关于 Cause runtime exceptions to be properly ordered with println in console output

问题 A common problem with VM Java console output is that System.out and System.err are not usually synchronized properly, possibly because they are on different threads. This results in mixed up output such as the following: debugging output mixed up with runtime exception stack trace [8, 1, 3, 5, 9, 13, 15, 17, 19] Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 9 scanning xAnswer: 1 xValue: 1 total: 1 [1, 1, 0, 0, 0, 0, 0, 0, 0] at cra.common.Group_jsc.listSubsetSum(Group

How to Map System.out and System.in to SWT controls

阅读更多关于 How to Map System.out and System.in to SWT controls

问题 I am working on on a tool to connect to a remote server using jcraft.JSch (ssh to Unix server) and return the output and display its output. The script works fine when channel input outputs are System.in and System.out . But when I try with SWT controls, it is not able to display the exact output I am getting with System.out read from SWT Text control emulating System.in public void create() { dialogShell = new Shell(dialogShell, SWT.PRIMARY_MODAL | SWT.SHEET | SWT.RESIZE); GridLayout

why we use system.out.flush()? [duplicate]

阅读更多关于 why we use system.out.flush()? [duplicate]

问题 This question already has answers here : When/why to call System.out.flush() in Java (4 answers) Closed 6 years ago . Can someone please explain why we we would use system.out.flush() in a simpler way? If there could be a chance of losing data, please provide me with an example. If you comment it in the code below nothing changes! class ReverseApp{ public static void main(String[] args) throws IOException{ String input, output; while(true){ System.out.print("Enter a string: "); System.out

Java separate System.out for separate Classpath

阅读更多关于 Java separate System.out for separate Classpath

问题 I am developing an application which needs to call some Jenkins instances, to do this I am using the jenkins-cli .jar I could be calling the jar using the commandline to easily extract its output. Then however I need to parse exceptions myself. To properly handle exceptions I am now invoking the main method of the jar via reflection: URLClassLoader jenkinsClassloader = new URLClassLoader(new URL[]{"UrlToJenkins-Cli.jar"}, getClass().getClassLoader()); Class<?> jenkinsCli = Class.forName (

Print a carriage return in java on windows on console

阅读更多关于 Print a carriage return in java on windows on console

问题 On my OS X machine, the following line gives me a nice and easy way to track the state of my loops: for (int index = 0; index < 100; index++) for (int subIndex = index; subIndex < 100; subIndex++) System.out.print("\r" + index + "/" + subIndex + " "); But when I try to run the same thing on windows, it prints out newlines instead of a carriage return. How can I achieve the same simple method of tracking the process on windows? 回答1: I had the statement and it worked in the command prompt

How to add empty space inside int?

阅读更多关于 How to add empty space inside int?

问题 Let's say I want to print the number 100000000. At first sight it is difficult to tell how many millions this number is representing. Is it 10 million or 100 million? How can I make big numbers in Java look more readable? Something like this for instance would be great: 100 000 000 . You can tell right away that the number is 100 million. 回答1: You can also try DecimalFormat; DecimalFormat formatter = new DecimalFormat("#,###"); System.out.println(formatter.format(100000)); Results: 1000>>1

How to make a Logger for System.out

阅读更多关于 How to make a Logger for System.out

问题 I am wondering how to get org.slf4j.Logger for System.out. I know this is not good, but I need it for testing purposes. Thank you so much. 回答1: Consider slf4j-simple, but it logs to stderr instead of stdout. It's the bare-minimum implementation. Source code browsable here: http://grepcode.com/file/repo1.maven.org/maven2/org.slf4j/slf4j-simple/1.6.1/org/slf4j/impl/SimpleLogger.java?av=f 回答2: It is possible to use slf4j-simple and make it write to the standard output by setting a system

Disable System.out for speed in Java

阅读更多关于 Disable System.out for speed in Java

问题 I'm writing a program in java that simulates gravity, and in it I have a bunch of log statements (to System.out). My program is running really slowly, and I think the logging might be part of the reason. Is there any way to disable System.out, so that my program doesn't slow down when printing, or do I have to manually go through and comment/uncomment each one to enable/disable debug statements? Any help would be appreciated. 回答1: I agree with others that a proper logger should be used.

Cause runtime exceptions to be properly ordered with println in console output

阅读更多关于 Cause runtime exceptions to be properly ordered with println in console output

A common problem with VM Java console output is that System.out and System.err are not usually synchronized properly, possibly because they are on different threads. This results in mixed up output such as the following: debugging output mixed up with runtime exception stack trace [8, 1, 3, 5, 9, 13, 15, 17, 19] Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 9 scanning xAnswer: 1 xValue: 1 total: 1 [1, 1, 0, 0, 0, 0, 0, 0, 0] at cra.common.Group_jsc.listSubsetSum(Group_jsc.java:29) scanning xAnswer: 2 xValue: 2 total: 4 [2, 1, 2, 0, 0, 0, 0, 0, 0] at cra.common.Group_jsc