不要在JAVA中从字符串的开始/结尾修剪选项卡（\\ t）

Question

I have an input stream which has fields separated by tab(\\t) which looks like this

String str = "  acc123\tdpId123\t2011-01-01\t2022-01-01\thello@xyz.com\tIN\t1233\tSOMETHING      ";

which works fine when I do str = str.trim(); and

strArray = str.split("\t", -1); 
strArray=["acc123","dpId123","2011-01-01","2022-01-01","hello@xyz.com","IN","1233","SOMETHING"] will give size as 8 

But last field in the input record is not mandatory and can be skipped.

So the input can look like this too.

 String str1 = "acc123\tdpId123\t2011-01-01\t2022-01-01\thello@xyz.com\tIN\t1233\t";

but in this case last field should be empty but when I use this string after trim and split my size is 7

str1 = str1.trim();      
strArray = str1.split("\t", -1); 
      strArray=["acc123","dpId123","2011-01-01","2022-01-01","hello@xyz.com","IN","1233"]will give size as 7

But I want

strArray=["acc123","dpId123","2011-01-01","2022-01-01","hello@xyz.com","IN","1233",""]

How can I avoid this situation?

Answer 1

There you go:

String str1 = "   acc123\tdpId 123\t201 1-01-01\t2022-01-01\thello@xyz.com\tIN\t1233\t";
str1 = str1.replaceAll("^[ ]+", ""); // removing leading spaces
str1 = str1.replaceAll("[ ]+$", ""); // removing trailing spaces
String[] split = str1.split("\t", -1);

System.out.println(Arrays.toString(split));
System.out.println(split.length);

String#trim method also removes \\t . To handle that I have removed only the leading and trailing spaces using regex.

Output:

[acc123, dpId 123, 201 1-01-01, 2022-01-01, hello@xyz.com, IN, 1233, ]
8

Answer 2

You can use split like so :

String[] split = str.split("\t", -1); // note the -1

To avoid spaces you can use

 Arrays.stream(split).map(String::trim).toArray(String[]:new);

Answer 3

you can use limit parameter to solve this str.split("\\t",-1) .

The limit parameter controls the number of times the pattern is applied and therefore affects the length of the resulting array.

read more about split limit in the docs .

Example:

public class GFG { 
    public static void main(String args[]) 
    { 
        String str = "a\tb\tc\t"; 
        String[] arrOfStr = str.split("\t",-1); 

        for (String a : arrOfStr) 
            System.out.println(a);
        System.out.println(arrOfStr.length);
    } 

} 

Answer 4

The conceptually correct way to do this in your case is to split first , only then trim first and last elements:

String[] array = str.split("\t");
array[0] = array[0].trim();
int last = array.length -1;
if (last > 0) {
    array[last] = array[last].trim();
}

Also, if you know upfront how many fields there is supposed to be, then you should also use that knowledge, otherwise you can get an invalid number of fields still:

int fieldsCount = getExpectedFieldsCount();
String[] array = str.split("\t", fieldsCount);

---

Lastly, I advise you to not use whitespace as the data separator. Use something else. For example, see CSV format, it's a lot better for these things.

Answer 5

Try this (the result array is in the variable resultArray):

    String str1 = "acc123\tdpId123\t2011-01-01\t2022-01-01\thello@xyz.com\tIN\t1233\t";
    String[] strArray = str1.split("\t");
    String regex = ".*\\t$";
    String[] resultArray;
    if (str1.matches(regex)) {
        resultArray = new String[strArray.length + 1];
        resultArray[strArray.length] = "";
    } else {
        resultArray = new String[strArray.length];
    }
    for (int i= 0; i < strArray.length; i++) {
        resultArray[i] = strArray[i];
    }

    System.out.println(resultArray.length);
    System.out.println(Arrays.toString(resultArray));