java - Which one is better in calling a function: two times or storing the result in a variable? -

i have got doubt many times, didn't figure out correct soltion. time want clear off. have situation like

1.  string snumber="ksadfl.jksadlf"; if(snumber.lastindexof('.')>0)    //do ... ... if(snumber.lastindexof('.')>1)  //do ...  2. int index = snumber.lastindexof('.'); if(index>0) //do ... ... if(index>1) //do ... 

what trade offs between first way , second way? 1 better in storing result in variable or calling function 2 times?

in example, 2nd form better (in plausible situations¹) performance perspective, , (imo) more readable.

in general, there couple of trade-offs consider:

• is readability more important efficiency?
• how of "performance hit" call method twice versus once?

also, need consider cases method may have side-effects, , whether may give different answer on 2 successive calls. in cases, calling method twice semantically different calling once , storing result in temporary variable.

---

^{1 - index variable makes stack frame 1 word larger. doesn't matter, if code in recursive method gets called in recursive fashion, 1 word multiplied number of nested calls result in stackoverflowerror.}