How to Convert double to String in Java?

public class StudyTonight
{  
    public static void main(String args[])
    {  
        double n = 500.88;  
        String s=String.valueOf(n); 
        System.out.println("The string value is " +s);
        System.out.println(n+100); //will return 600.88 because + is binary plus operator 
        System.out.println(s+100);//will return 500.88100 because + is string concatenation operator  
    }
}

public class StudyTonight
{  
    public static void main(String args[])
    {  
        double n = 500.77;  
        String s = Double.toString(n); 
        System.out.println("The string value is " +s);
        System.out.println(n+100); //will return 600 because + is binary plus operator 
        System.out.println(s+100);//will return 500100 because + is string concatenation operator  
    }
}

import java.text.DecimalFormat;
public class StudyTonight
{  
    public static void main(String args[])
    {  
        double num = 500.88;  
        System.out.println(String.format ("%f", num));
        System.out.println(String.format ("%.9f", num));
        DecimalFormat decimalFormat = new DecimalFormat("#,##0.000000");
        String numberAsString = decimalFormat.format(num);
        System.out.println(numberAsString);
    }
}

public class StudyTonight
{  
    public static void main(String args[])
    {  
        double num = 500.88;  
        String s = num+""; //concat
        System.out.println(s);
    }
}