What is the difference between Double parseDouble String and Double valueOf String

Question

I want to convert String to a Double data type  I do not know if I should use parseDouble or valueOf   What is the difference between these two methods

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Double parseDouble String  will return a primitive double type  Double valueOf String  will return a wrapper object of type Double   So  for e g    double d   Double parseDouble  1     Double d   Double valueOf  1      Moreover  valueOf      is an overloaded method  It has two variants    Double valueOf String s  Double valueOf double d    Whereas parseDouble is a single method with the following signature    double parseDouble String s

User · Answer

They both convert a String to a double value but wherease the parseDouble   method returns the primitive double value  the valueOf   method further converts the primitive double to a Double wrapper class object which contains the primitive double value    The conversion from String to primitive double may throw NFE NumberFormatException  if the value in String is not convertible into a primitive double

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If you want to convert string to double data type then most choose parseDouble   method  See the example code   String str    123 67   double d   parseDouble str     You will get the value in double  See the StringToDouble tutorial at tutorialData

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Documentation for parseDouble   says  Returns a new double initialized to the value represented by the specified String  as performed by the valueOf method of class Double    so they should be identical

User · Answer

parseDouble returns a primitive double containing the value of the string      Returns a new double initialized to the value represented by the specified String  as performed by the valueOf method of class Double    valueOf returns a Double instance  if already cached  you ll get the same cached instance      Returns a Double instance representing the specified double value  If   a new Double instance is not required  this method should generally be   used in preference to the constructor Double double   as this method   is likely to yield significantly better space and time performance by   caching frequently requested values    To avoid the overhead of creating a new Double object instance  you should normally use valueOf

User · Answer

parseDouble   method is used to initialise a STRING  which should contains some numerical value     the value it returns is of primitive data type  like int  float  etc   But valueOf   creates an object of Wrapper class  You have to unwrap it in order to get the double value  It can be compared with a chocolate  The manufacturer wraps the chocolate with some foil or paper to prevent from pollution  The user takes the chocolate  removes and throws the wrapper and eats it   Observe the following conversion   int k   100  Integer it1   new Integer k    The int data type k is converted into an object  it1 using Integer class  The it1 object can be used in Java programming wherever k is required an object   The following code can be used to unwrap  getting back int from Integer object  the object it1   int m   it1 intValue      System out println m m      prints 10000    intValue   is a method of Integer class that returns an int data type

[java] What is the difference between Double.parseDouble(String) and Double.valueOf(String)?

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