从文本文件读取时，Java空指针异常

Question

I am having trouble reading from a text file and i keep getting the error "java null pointer exception"

My read file class is

public class readfile {
    private Scanner x;

public void openfile() {
    try {
        x = new Scanner(new File("test2.txt"));
    }
    catch(Exception e) {
        System.out.println("error");
    }
}

public void readfile() {
    while(x.hasNext()) {
        String a = x.next();
        String b = x.next();
        String c = x.next();

        System.out.printf("%s %s %s",a,b,c);
    }
}

and my main class to call these methods is

public class InputOut {

public static void main(String[] args) {
   readfile r = new readfile();
   r.openfile();
   r.readfile();
   r.closeFile();
   }

}

i get the error when i call the readfile exception so i believe i might not be opening it correctly? I saved the file in the directory where the program is run and has the follwoing format

50 issac billy
432 bryan darren
443 rob zombie

did i miss something to read files here. I imported the java.io*; class and the java.util class as well. Error occurs at public void readfile()

Answer 1

Just a quick guess... Your code is

while(x.hasNext()) {
    String a = x.next();
    String b = x.next();
    String c = x.next();

hence you are checking if ONE element exists (via hasNext() ). Checking is always a good idead. But then you should read only the next element (via next() ) and not further without checking again.