How can i find the first index of date and time in string in Java-CodePudding

I have this string with YYYY-MM-DD HH:MM:SS date and time format as below:

String JAVA_STACK_TRACE = "ABC-007: This is a dummy ABC error message. This message can have multiple sentences." " 2021-09-24 19:12:50,672 Exception in thread \"main\" java.lang.RuntimeException: A test exception" " at com.stackify.stacktrace.StackTraceExample.methodB(StackTraceExample.java:13)" " at com.stackify.stacktrace.StackTraceExample.methodA(StackTraceExample.java:9)" " at com.stackify.stacktrace.StackTraceExample.main(StackTraceExample.java:5)";

I want to extract "ABC-007: This is a dummy DCS error message." this part from the string and neglect all the exception stack trace.

I was thinking that if I get the index of the date, I can do a sub string from the index 0 to the index of date.

I am not good with regex so haven't tried anything. Thanks in advance.

CodePudding user response：

Assuming the timestamp be the correct marker, you could try stripping it off along with all following content:

String output = JAVA_STACK_TRACE.replaceAll("\\s \\d{4}-\\d{2}-\\d{2} \\d{2}:\\d{2}:\\d{2}.*$", "");
System.out.println(output);

This prints:

ABC-007: This is a dummy ABC error message. This message can have multiple sentences.

CodePudding user response：

Tim Biegeleisen’s simple code seems to be the best to obtain your real goal: extract the message before the date.

Since you asked for the index of the date, for the sake of completeness I wanted to show you that a regular expression can be used for that too:

    Pattern p = Pattern.compile("\\d{4}-\\d{2}-\\d{2} \\d{2}:\\d{2}:\\d{2},\\d{3}");
    Matcher m = p.matcher(JAVA_STACK_TRACE);
    
    if (m.find()) {
        int indexOfDateAndTime = m.start();
        System.out.println("Index: "   indexOfDateAndTime);
    } else {
        System.out.println("Not found");
    }

Output:

Index: 86

The start() method of Matcher gives you the index of where the match started, the first matched character. There is a corresponding end method giving us the offset after the last character matched.

It’s a detour if all you want is the message, though.