The difference between the Double class parsedouble () and the valueof () method

String literals of numeric types are converted to floating-point numbers usually using the parsedouble () and valueof () methods.

There are two differences between the two main points.

Difference One: Parameter difference
Double.parsedouble (java.lang.String) parameter can only be String if the argument is changed to a double type hint "the method parsedouble (String) in the type double Is isn't applicable for the arguments (double) "error.
The parameter types for double.valueof () can be floating-point or string-capable.

1  Public voidTesttem () {2System.out.println ("==================");3String pi = "3.1415926";4Double doubleValue1 =double.valueof (pi);5Double doubleParse1 =double.parsedouble (pi);6System.out.println (String.Format ("doubleValue1 =%s, DoubleParse1 =%s", DoubleValue1, doubleParse1));7 8Double piofdouble = 3.1415926;9Double doubleValue2 =double.valueof (piofdouble);TenDouble DoubleParse2 =double.parsedouble (piofdouble.tostring ()); OneSystem.out.println (String.Format ("doubleValue2 =%s, DoubleParse2 =%s", DoubleValue2, DoubleParse2)); A  -Float pioffloat =float.valueof (pi); -Double DoubleValue3 =double.valueof (pioffloat); theDouble DOUBLEPARSE3 =double.parsedouble (pioffloat.tostring ()); -System.out.println (String.Format ("DoubleValue3 =%s, DoubleParse3 =%s", DoubleValue3, doubleParse3)); -System.out.println ("=================="); -}

Console output Results:

1 ==================2 doubleValue1 = 3.1415926, doubleParse1 = 3.14159263 doubleValue2 = 3.1415926, DoubleParse2 = 3.14159264 doubleValue3 = 3.141592502593994, doubleParse3 = 3.14159255 ===== =============

Difference Two: return type
Double.parsedouble (java.lang.String) converts a string of numeric type to a double type
Double.valueof () to convert a string of numeric type to a double type
Source code for the Double.parsedouble () method:

     Public Static Double throws numberformatexception {            return  floatingdecimal.readjavaformatstring (s). Doublevalue ();    } 

Source code for the Double.valueof () method:

     Public Static throws numberformatexception {        //  new Double ()            returnNew  Double (floatingdecimal.readjavaformatstring (s). Doublevalue ());    }

By formatting the number of decimal places the result is the same, you can see that the difference between the parameter and the return type is small.

    New DecimalFormat ("0.00");    System.out.println (Df.format (double.parsedouble (PI)));    System.out.println (Df.format (double.valueof (PI)));

Console output Results:

    3.14    3.14

Ref: 78115171

The difference between the Double class parsedouble () and the valueof () method