问读取文件时Java中出现空指针异常

EN

public class PageRank{
public static class ReadInput{
    private Scanner x;
    public void OpenFile(){
        try {
            File file  = new File("input.txt");
            Scanner x=new Scanner(file);
       }
        catch(Exception e){
            System.out.println("File does not exist.");
        }


    }
    public void ReadFile() {
        while (x.hasNextLine() ) {
            String s = x.nextLine();
            System.out.println(s);
            String s1 = x.nextLine();
            String s2 = x.nextLine();
            System.out.println(s);
            System.out.println(s1);
            System.out.println(s2);
        }
    }

    }
public static void main(String[] args)throws Exception
    {
    ReadInput P = new ReadInput();
    P.OpenFile();
    P.ReadFile();
      }