如何使用循环在java中创建表

Question

In class I got the following problem:

Write a class that contains the folowing two methods:

/** Convert from Celsius to Fahrenheit */
public static double celsiusToFahrenheit(double celsius)

/** Convert from Fahrenheit to Celsius */
public static double fahrenheitToCelsius(double fahrenheit)

The formula for te conversion is:
fahrenheit = (9.0 / 5) * celsius + 32
celsius = (5.0 / 9) * (fahrenheit - 32)

write a test program that invokes these methods to display th following tables:

celsius  Fahrenheit  |  Fahrenheit  celsius
___________________________________________
40.0 104.0 | 120.0 48.89

39.0 102.2 | 110.0 43.33

...

32.0 89.6 | 40.0 4.44

31.0 87.8 | 30.0 -1.11

---

I have tried the following code:

public static double celciusToFahrenheit(double celcius) {
    double fahrenheit = (9.0 / 5) * celcius + 32;
    return fahrenheit;
}

public static double fahrenheitToCelcius(double fahrenheit) {
    double celcius = (5.0 / 9) * (fahrenheit - 32);
    return celcius;
}
public static void main(String[] args) {
    // TODO Auto-generated method stub

    System.out.println("Celcius\tFahrenheit\t|\tFahrenheit\tCelcius");

    for (int i = 0; i < 10; i++ ) {
        for (int a = 40; a > 30; a--) {
            System.out.print(i + "\t" + celciusToFahrenheit(i) + "\t|\t");
        }
        for (int b = 120; b > 30; b -= 10) {
            System.out.print(i + "\t" + fahrenheitToCelcius(i) + "\n");
        }
    }

}

The problem is that in the "main" loop it first loops through the first loop and after that in runs the second loop. But in order to display a table it has to alter between the first loop. or do I have to take an entire other approach.

Answer 1

Try this:

 for (int i = 0; i < 10; i++ ) {
        System.out.print((40-i) + "\t" + celciusToFahrenheit((40-i)) + "\t|\t");

        System.out.print((120 - (i * 10)) + "\t" + fahrenheitToCelcius((120 - (i * 10))) + "\n");
    }
}

Edit:

Here's the full code: http://ideone.com/q9o5G2

Answer 2

You have too many for-loops in there. You just need one:

for (int i = 0; i < 10; i++ ) {
    double celcius = 40 - i;
    double convertedCelcius = celciusToFahrenheit(celcius);
    double fahrenheit = 120 - (i * 10);
    double convertedFahrenheit = fahrenheitToCelcius(fahrenheit);

    System.out.print(celcius + "\t" + convertedCelcius + "\t|\t" + fahrenheit + "\t" + convertedFahrenheit + "\n");
}