String.split（）-如何区分制表符分隔值和逗号分隔值？

Question

I'm collecting column data types from files using Java. Some files are tab separated and some are comma-separated. Came with the following code:

String[] valuesFromColumns = null;
                   if (line.split("\\s*\\t\\s*") != null) {

                    System.out.println("Separating by tab: " + line);
                            valuesFromColumns = line.split("\\s*\\t\\s*");

                    } else if(line.split("\\s*,\\s*")!=null) {
                    System.out.println("Separating by comma." + line);
                            valuesFromColumns = line.split("\\s*,\\s*");
                    } 

                    for(String s : valuesFromColumns) {
                        this.extractDataTypeFromTheLine(s);
                 }

The output is not what's expected: it mistakes comma separated files for tab-separated values. What am I possibly doing wrong? Here is the output:

/Users/macbook/open_data_us/GPL94-tbl-1.txt
Separating by tab: 67023_at AI342132        Homo sapiens    Mar 11, 2009    Consensus sequence  GenBank Cluster Incl. AI342132:qt26c08.x1 Homo sapiens cDNA, 3' end /clone=IMAGE-1949102 /clone_end=3' /gb=AI342132 /gi=4079059 /ug=Hs.156499 /len=414  AI342132                            
String
String
String
...
/Users/macbook/open_data_us/Performance Metrics - Transportation.csv
Separating by tab: Alley Pot Hole,06/06/2011,Week,10,1.65,3,06/06/2011 - 06/12/2011
String
/Users/macbook/open_data_us/redditSubmissions.csv
Separating by tab: 0,1333178161,2012-03-31T14:16:01.093638-07:00,Expectation,35,rmun4,29,GifSound,6,1333203361,23,3,Gangsta_Raper
String

Answer 1

line.split does not return null when the regular expression doesn't find any matches. Instead it returns an array with the whole line as the first and only element.

Therefore the first condition ais always true.