【java performance】将try/catch块移出循环

把try/catch块放入循环体内，会极大的影响性能，如果编译JIT被关闭或者你所使用的是一个不带JIT的JVM，性能会将下降21%之多!

         

例子：        

import java.io.FileInputStream;

public class TRY {

   void method (FileInputStream fis) {

       for (int i = 0; i < size; i++) {

           try {                                      //violation

                _sum += fis.read();

            } catch (Exception e) {}

       }

    }

   private int _sum;

}

        

更正：        

将try/catch块移出循环        

   void method (FileInputStream fis) {

       try {

           for (int i = 0; i < size; i++) {

                _sum += fis.read();

           }

       } catch (Exception e) {}

    }

        

参考资料：

Peter Haggar: "Practical Java -Programming Language Guide".

Addison Wesley, 2000, pp.81 – 83