Question

java 类*******没有主方法，是怎么回事

下面是程序
import java.io.*; //tells Java input will be used
class PartThree5
{
public class ConvertingFahrenheit
{

int fahrenheit;
int celsius;

public void convertingF() {
fahrenheit = (9 / 5) * celsius + 32;
System.out.println(celsius+ " celsius"+ " = " + fahrenheit + " fahrenheit" );
}
}
public class ConvertingCelsius
{

int fahrenheit;
int celsius;

public void convertingC() {
celsius = (5 / 9) * (fahrenheit - 32);
System.out.println (fahrenheit+" fahrenheit=" + celsius + " celsius");
}
}
public class ConvertingTester{
public static void main(String [] args) throws IOException
{

String inData;
ConvertingFahrenheit cf= new ConvertingFahrenheit();
ConvertingCelsius cc= new ConvertingCelsius();

InputStreamReader inStream = new InputStreamReader (System.in);
BufferedReader stdin = new BufferedReader (inStream);

System.out.println ("Input fahrenheit:");
inData = stdin.readLine ();
cf.fahrenheit = Integer.parseInt (inData);

System.out.println ("Input celsius:");
inData = stdin.readLine ( );
cc.celsius= Integer.parseInt (inData); /*converts inData character
data to int data type*/

}
Design an object oriented Celsius-Fahrenheit converter program. Your program will have two methods—one for converting Celsius temperature to Fahrenheit temperature and one method for converting Fahrenheit temperature to Celsius temperature. The user will input a temperature on one temperature scale and the program will output the converted temperature.

Your method should have a return type and one parameter. The formula for conversion is:
fahrenheit = (9.0 / 5.0) * celcius + 32

谢谢啦

Answer 1

main函数不能放在子类ConvertingTester里，而应该直接放在PartThree5类下面。而且PartThree5类也应该是public。

追问

两个class和另外一个tester可不可以放到一个java文件里面运行？

追答

1. 一个java文件只能有一个public class，而且main函数必须是这个class的成员。

2. 可以有其他的类，只要不是public就可以。