java - 使用FileWriter的java.lang.NullPointErexception

我正在使用BufferedWriter在类的构造函数中写入新创建的文本文件。该类创建文本文件，然后向其中添加初步文本，以使读取操作不会返回错误。但是，当我尝试添加此初步文本时，特别是在以下方法中使用writeHigh时，会收到一个java.lang.NullPointerException。我认为这与传入的字符串无关，但是我也尝试过更改writeHigh的实例化，但没有执行任何操作。我希望有人可能知道此错误的原因。堆栈跟踪没有帮助。

    try
    {
        //New buffered writters that can write to the specified files.
        writeHigh = new BufferedWriter(new FileWriter(HIGH_SCORE_PATH, false));

        //highScore = Integer.parseInt(readScore.readLine());
    }
    catch(FileNotFoundException e) //If reading from these files fails because they don't yet exist...
    {
        File highFile = new File(HIGH_SCORE_PATH); //Create a new high score file, this is the first time the game has been played.

       try
       {
           highFile.createNewFile();
           writeHigh.write("0000"); //This line is throwing the error
       }
       catch(IOException i)
       {
           i.printStackTrace();
       }
    }
    catch(IOException e)
    {
        e.printStackTrace();
    }

最佳答案

这条线给你扔了NPE

writeHigh.write("0000");

并且只有在捕获到FileNotFoundException的情况下，您才能到达此行。这意味着该行抛出该异常

writeHigh = new BufferedWriter(new FileWriter(HIGH_SCORE_PATH, false));

如果它引发了异常，则表示它执行失败，则尚未实例化writeHigh。因此writeHigh为null。因此writeHigh.write("0000");抛出一个NPE。



我想你想做

highFile.write("0000");