decompiled code is different from original code

Question

I decompiled a .jar file using jd-gui and checked codes, I found it different from original .java file.

• original code

  if ( total != 0 ) {
      result[ i ] = bdResult.multiply( bdItem ).divide( bdTotal, 0,
      RoundingMode.DOWN ).setScale( 0, RoundingMode.DOWN ).intValue();
  }
  

• decompiled code

  if (total == 0)
    continue;
  result[i] = bdResult.multiply(bdItem).divide(bdTotal, 0, 
  RoundingMode.DOWN).setScale(0, RoundingMode.DOWN).intValue();
  

Why this happens?

In addition, decompiled code seems grammatically wrong( where curly bracket goes?)

Answer 1

Decompile code always tries to do the same thing as the source code, but are written in a different way because of the optimizations of the compiler. They are some decompiler that are better than other, check that article

Answer 2

It's impossible to get the original code by decompiling just because different code can lead to the same java byte code statements. However, you are getting an equivalent version which performs exactly the same actions as the original.