I've improved the expression a little.
Replace
(\t+)(\s*)(\S*) = (\S*);
with
$1$2$4 = $3;
The reason is, it will look for lines starting with tab (\t). It will skip the lines starting with definition. E.g.:
TestClass tc = new TestClass();
int a = 75;
int b = 76;
int c = 77;
a = tc.a;
b = tc.b;
a = tc.c;
Would ignore the int a, int b and int c and swap only the assignments.