String.split()生成NullPointerException

Kaz*_*ara 2 java string

String.split()生成NullPointerException.

BufferedReader brs = new BufferedReader(new InputStreamReader(System.in));
String s1;
String s2[];
s1 = brs.readLine();
s2 = s1.split(" ");
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ada*_*ost 14

s1可能是null,

s1 = brs.readLine();
if(s1!=null)
 s2 = s1.split(" ");
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