JAVA 非法启动类型

Question

My program:

public class m
{
    public static void main (String[] args)
    {
        boolean bool = true;

        while(bool)
        {
            rand_number player_1 = new rand_number();
            System.out.println("Player_1 guessed " + player_1.rand_n);

            rand_number player_2 = new rand_number();
            System.out.println("Player_2 guessed " + player_2.rand_n);

            rand_number player_3 = new rand_number();    
            System.out.println("Player_3 guessed " + player_3.rand_n);

            if(player_1.guessed || player_2.guessed || player_3.guessed)
            {
                System.out.println("We have a winner");   
                bool = false;
            }
        }
    }
}

class rand_number
{
    int rand_n = (int)(Math.random() * 10);

    if(rand_n == 2) 
    {
        boolean guessed = true;
    }
}

I'm getting this error: m.java:31: illegal start of type . The syntax is absolutely right, I have checked it million times. What's wrong?

Answer 1

class rand_number
{
    //...    
    if(rand_n == 2) 
    {
        boolean guessed = true;
    }
}

You can only have field declarations at the class level. An if statement like this needs to be in a method, constructor, or initializer block.

You could eliminate the if statement like this:

boolean guessed = rand_n == 2;

But I question why you have any desire to set this value at creation time at all, as opposed to in response to some user action.

Answer 2

Your syntax is absolutely wrong. rand_number doesn't contains methods and yet tries to do conditions.

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If you want to do random numbers you should try the Random class like this :

Random random = new Random();
int numberToFind = random.nextInt(2);

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You should take a look at the Java naming conventions , it helps to have a clean code that any java developer can understand in a second. For example, start your classes names with an uppercase.