In java, after the String type string s is assigned null, the String is spliced with other strings to obtain the style of the null string connected to other characters. The String value is null.

In java, after the String type string s is assigned null, the String is spliced with other strings to obtain the style of the null string connected to other characters. The String value is null.

String s = null;

S + = "hello ";

System. out. println (s );

The result is: nullhello.

Cause:

Use String. valueOf to obtain the value of s and then concatenate hello through StringBuilder. Therefore, the value and hello are spliced;

String s = null;
S = (new StringBuilder (String. valueOf (s). append ("hello"). toString ();
System. out. println (s );