double与String之间的相互转换方法

8种基本数据类型有相应的8种包装类(Wrapper)对应,分别是:Character,Byte,Short,Integer,Long,Float,Double,Boolean.

特点:

1.提供了valueOf(String)用于从字符串转换及toString()转换成字符串

2.通过xxxxValue()方法可以得到所包装的值,如Integer对象的intValue()方法.

示例代码:

public class DoubleAndString {

public static void main(String[] args) {
   double d;
   String s;
   System.out.println("===Change double to String===");
   d = 3.1415926;// double d
   s = "" + d;// this is a interesting convert way
   System.out.println("s is " + s);
   s = new Double(d).toString();// toString(String) method
   System.out.println("s is " + s);
   s = String.valueOf(d);// valueOf(String) method
   System.out.println("s is " + s);

   System.out.println("===change String to double===");
   s = "6.12345";
   try {
    d = new Double(s).doubleValue();//xxxValue() method

　　    System.out.println("d is " + d);

　　    //Returns a new double initialized to the value represented
    //by the specified String
    d = Double.parseDouble(s);
    System.out.println("d is " + d);
    d = Double.valueOf(s).doubleValue();//doubleValue() method
    System.out.println("d is " + d);
   } catch (Exception e) {
    e.printStackTrace();
   }

}

}