Question

我正在尝试将用户选择的首选项保存到文本文件中。当我保存某些内容然后尝试向其添加信息时，它会被覆盖。我检查了日志，看来当我读取文件以检查之前是否有任何内容写入时，它只读取3行，即使我检查了文件，它有6行。

我使用savefiles方法下面编写的类SoundDetails实例调用名为saveFiles的方法：

   public static void saveFiles(SoundDetails s) {
        try {
        Scanner readDatabasetoSave  = new Scanner(file);
        PrintWriter write = new PrintWriter(file);
        String everyThing = "";
        while(readDatabasetoSave.hasNext()){
            everyThing += readDatabasetoSave.nextLine();
            Log.e(everyThing, everyThing);
        }
        int index = everyThing.indexOf('#');

        if(index != -1){
            everyThing = everyThing.substring(0,index); 
        }
        everyThing = everyThing + s.name + "\n" +s.time + "\n" + s.onoff +"\n";
        Log.d("everything final", everyThing);
        //Log.e("everything",everyThing);
        for(boolean b : s.daysofweek){
            if(b == true){
                everyThing += "T";
            }
            else{
                everyThing += "F";
            }
        }
        everyThing += "\n";
        for(boolean b : s.sensors){
            if(b == true){
                everyThing += "T";
            }
            else{
                everyThing += "F";
            }
        }
        everyThing += "\n"+s.profile+"#";
        write.print(everyThing);
        write.close(); 
    } catch (FileNotFoundException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
        Log.e("error occured", e.toString());
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } 
}

这是SoundDetails类：

public class SoundDetails {
    public boolean[] sensors ; // wifi gps 3g bluetooth airplane
    public boolean[] daysofweek ;
    public boolean onoff ;
    public String profile;
    public String name;
    public String time;
    public SoundDetails(boolean[] sensors, boolean[] daysofweek,String profile,boolean onoff,String name,String time){
        this.sensors = sensors;
        this.daysofweek = daysofweek;
        this.profile = profile;
        this.onoff = onoff;
        this.name = name;
        this.time = time;
    }
}

Answer 1

嗯，没有深入研究这个问题，似乎问题可能是你正在使用indexOf ...

    int index = everyThing.indexOf('#');

    if(index != -1){
        everyThing = everyThing.substring(0,index); 
    }

...当你用其余代码判断时，我想你实际上在寻找最后一个索引：

    int index = everyThing.lastIndexOf('#');

    if(index != -1){
        everyThing = everyThing.substring(0,index); 
    }

此外，在关闭流之前刷新流通常是个好主意：

    write.print(everyThing);
    write.flush(); //since the printwriter you're using does not autoflush
    write.close();

Answer 2

如果您问题的第一行是准确的（“我正在尝试将用户选择的首选项保存到文本文件中。”）那么我想知道您是否只是做了太多的工作。

您是否有特定原因未使用内置偏好设置管理器ala http://developer.android.com/guide/topics/ui/settings.html？

为什么扫描仪实例只读取3行代码

2 个答案: