Comparison string, equals Air Defense pointer problem, equals Air Defense

Comparison string, equals Air Defense pointer problem, equals Air Defense

1. Use. equals (B) Comparison, where a and B are two strings, using a = B to compare the memory addresses of a and B.
2. If one string is a variable and the other string is a constant, you must write the constant in front and the variable in the back (in parentheses). There is only one reason for this writing, avoid NULL pointer exceptions. For example, if a is a constant string and B is a variable string, it must be written as. equals (B ). cannot be written as B. equals (a). Otherwise, if B is null, a null pointer exception is definitely reported.

For beginners, pay attention to these two points.

Hope to help you