对java中的文件进行操作

Question

我在使用java中的所有FileReader和FileWriters时遇到了一些问题。我希望我的程序能够得到这个人的名字，然后在询问他们几个问题后评估他们的分数。这是很容易的，但现在我想要做的就是记录它在这样的日志文件：每次这些人打开程序会检索其当前得分

Jacob : 10 
Mark : 15 
Steve : 7 

然后，或者如果它是一个新的它会追加他们的名字和分数。 我无法找到搜索文件的方法，然后在最后检索整数。

编辑：

import java.io.FileInputStream; 
import java.io.FileOutputStream; 
import java.io.ObjectInputStream; 
import java.io.ObjectOutputStream; 
import java.util.Scanner; 

public class Main { 
    static Scores scoreClass = new Scores(); 

    private static void setupMap() { 
     try { 
      FileInputStream fin = new FileInputStream("scores.map"); 
      @SuppressWarnings("resource") 
      ObjectInputStream ois = new ObjectInputStream(fin); 
      scoreClass = (Scores) ois.readObject(); 
      } catch (Exception e) { 
       System.err.println("Could not load score data"); 
       e.printStackTrace(); 
      } 
    } 
    private static void saveMap() { 
     try { 
      FileOutputStream fout = new FileOutputStream("scores.map"); 
      @SuppressWarnings("resource") 
      ObjectOutputStream oos = new ObjectOutputStream(fout); 
      oos.writeObject(scoreClass); 
     } catch (Exception e) { 
      System.err.println("Could not save score data"); 
      e.printStackTrace(); 
     } 
    } 

    public static void main(String[] args) { 
     setupMap(); 
     int score = 0; 
     String guess; 
     String[][] questions_with_answers = {{"I __________ to school.(go)", "She __________ tennis. (play)", "She _______ a bitch. (be)"}, {"am going", "was playing", "is being"}}; 
     Scanner answer = new Scanner(System.in); 
     Scanner studentInput = new Scanner(System.in); 
     System.out.println("What is your name?"); 
     String name = answer.nextLine(); 
     if(Scores.getScore(name) == -1){ 
      Scores.setScore(name, score); 
     } else { 
      Scores.getScore(name); 
     } 

     System.out.println("Hello " + name + ". Your score is: " + score); 
     for(int i = 0; i < (questions_with_answers[0].length); i++){ 
      System.out.println(questions_with_answers[0][i]); 
      guess = studentInput.nextLine(); 
      if(guess.equals(questions_with_answers[1][i])){ 
       System.out.println("Correct! You get 1 point."); 
       score = score + 1; 
       System.out.println("Your score is " + score); 
      } else { 
       System.out.println("You made a mistake! No points..."); 
      } 
     } 
     System.out.printf("Congrats! You finished the test with "+ score +" points out of " + questions_with_answers[0].length);  
     Scores.setScore(name, score); 
     saveMap(); 
     answer.close(); 
     studentInput.close(); 
    } 
} 

这不会引发任何异常，但仍然没有从文件中读取输入：/

Answer 1

您可以将数据存储为一个哈希表，然后序列化到一个保存文件

我写了一个示例，其中包含一个名为Scores的类，该类具有读取分数并将分数添加到包含的散列图的方法。我还在主类中添加了保存和打开包含分数类数据的文件的方法。

主类：

public class Main { 
    static Scores scoreClass = new Scores(); 

    public static void main(String[] args) { 
     setupMap(); 
     //Do score calculations 
     saveMap(); 

    } 
    private static void setupMap() { 
     try { 
      FileInputStream fin = new FileInputStream("scores.map"); 
      @SuppressWarnings("resource") 
      ObjectInputStream ois = new ObjectInputStream(fin); 
      scoreClass = (Scores) ois.readObject(); 
      } catch (Exception e) { 
       System.err.println("Could not load score data"); 
       e.printStackTrace(); 
      } 
    } 
    private static void saveMap() { 
     try { 
      FileOutputStream fout = new FileOutputStream("scores.map"); 
      @SuppressWarnings("resource") 
      ObjectOutputStream oos = new ObjectOutputStream(fout); 
      oos.writeObject(scoreClass); 
     } catch (Exception e) { 
      System.err.println("Could not save score data"); 
      e.printStackTrace(); 
     } 
    } 

} 

成绩等级：

public class Scores implements Serializable{ 
    private static final long serialVersionUID = 1L; 

    public static Map<String, Integer> scoreMap = new HashMap<String, Integer>(); 

    public static int getScore(String name) { 
     if (scoreMap.containsKey(name)) { 
      return scoreMap.get(name); 
     } else { 
      return -1; 
     } 
    } 

    public static void setScore(String name, int score) { 
     scoreMap.put(name, score); 
    } 
}