JavaでtoString（）を使用して数値の文字列表現を取得するにはどうすればよいですか？

public class ToStringMethodTest {
   public static void main(String args[]) {
      int num1 = 50;
      Integer num2 = 75;
      float flt1 = 50.75f;
      Float flt2 = 80.55f;
      double dbl1 = 3256522.44d;
      Double dbl2 = new Double(565856585d);
      //converting numbers to string format by toString()
      String str_int1 = Integer.toString(num1);
      String str_int2 = num2.toString();
      String str_flt1 = Float.toString(flt1);
      String str_flt2 = flt2.toString();
      String str_dbl1 = Double.toString(dbl1);
      String str_dbl2 = dbl2.toString();
      System.out.println("int to string = " + str_int1);
      System.out.println("Integer to string = " + str_int2);
      System.out.println("float to string = " + str_flt1);
      System.out.println("Float to string = " + str_flt2);
      System.out.println("double to string = " + str_dbl1);
      System.out.println("Double to string = " + str_dbl2);
   }  
}

出力

int to string = 50
Integer to string = 75
float to string = 50.75
Float to string = 80.55
double to string = 3256522.44
Double to string = 5.65856585E8