如何在main方法的静态方法下引用变量？

Question

My codes are like the following.

public class readfile {
    public static void readfile() {   
        int i = 0;  
        System.out.println("hello"); 
    }

    public static void main(String[] args) {  
        readfile(); 
        System.out.println(i); 
    }  
}

And it works well if I do not refer to the variable i. (That means it can print out hello.) So how can I refer i in the main method?

Answer 1

public class readfile {
    static int i;

    public static void readfile() {   
        i = 0;
        System.out.println("hello"); 
    }

    public static void main(String[] args) {  
        readfile(); 
        System.out.println(i); 
    }  
}

• As UUIIUI says in comment, if you declare i inside of readfile() , it is valid only inside of the method.
• As Murli says in comment, you need a member variable in the class field. And also it must be static one.

Answer 2

You are writing java code in a bad way :

1.First, the class name char in Java is Uppercase so your class need to be named ReadFile.

2. You cannot use the i variable in your main method, because it's just a local variable of your readFile method, and you have compilation errors, because of the use of i in the main method, and a warning in the readFile method, because you don't use it in the local block code.

Java appear new for you? and you need to learn a litle bit more. There's a full of book or documentation on the web.

Your sample corrected, compiled well and run well :

package stackWeb;

public class ReadFile {

    static int i = 0;  
    public static void readfile() {   

        System.out.println("hello"); 
    }

    public static void main(String[] args) {  
        readfile(); 
        System.out.println(i); 
    }  
}

Answer 3

You could try this

class readfile {
    static int i =0;
    public static void readfile() {   

        System.out.println("hello"); 
    }

    public static void main(String[] args) {  
        readfile(); 
        System.out.println(i); 
    }  
}