java in two floating-point compare

Compare inaccurate because the float in the computer

So be wrong judgment ==

Solutions

                Double preErrorKey =-1E. 6; // -6 power i.e. 0.000001 10 * 1 
                Double key1 = 0.0000001d ;
                 Double key2 = 0D;
 //                 System.out.println (== key1 key2); // result is flase
 / /                 System.out.println (the Math.abs (key1-key2) <preErrorKey); 
                IF (the Math.abs (daohuoshuliang- shengoushuliang) <preErrorKey && (weidaohuoliang == 0 )) { 
                    caigouzhuangtai = "purchase all";