Java中double类型的变量转换成字符串是什么样子的，还是和原来数值相同吗？

javaSe-1.7

    double d1 = 1;
    double d2 = 1.1;
    double d3 = 1.1111111111111111111111111111111;
    double d4 = 1.1111111111111111;
    double d5 = 1.111111111111111;      
    double d6 = 1.1111111111111110;
    System.out.println(String.valueOf(d1));//1.0
    System.out.println(String.valueOf(d2));//1.1
    System.out.println(String.valueOf(d3));//1.1111111111111112
    System.out.println(String.valueOf(d4));//1.1111111111111112     
    System.out.println(String.valueOf(d5));//1.111111111111111
    System.out.println(String.valueOf(d6));//1.111111111111111
    double d1 = 1;
    double