android - 将文件写入 getFilesDir() 失败 - NoSuchElementException

Question

这是我正在做的:

1- 从我的 Assets 中获取文件并将其放入字符串中 - 成功

2- 在 getFilesDir() 中创建一个文件 - 失败(还没有崩溃)

3- 使用 FileWriter 将我得到的字符串写入此文件 - 失败(尚未崩溃)

4- 读取我刚刚制作的新文件 - 失败(抛出 NoSuchElementException)

这是你必须看到的东西:

我用过的一个小有用的方法:

public String inputStreamToString(InputStream stream){

        Scanner s = new Scanner(stream).useDelimiter("\\A");
        String aa = s.next();
        return aa;

    }

MainActivity.java 的 fragment :

//B2 and text are a well defined Button and TextView respectively, ensured through previous testings
B2.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub

                AssetManager as = getAssets();
                InputStream stream = null;
                try {
                    stream = as.open("updater-script");
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
                Scanner s = new Scanner(stream).useDelimiter("\\A");
                String aa = s.next();
                text.setText(aa);

                File file = new File(getFilesDir() + "/updater-script");
                try {
                    boolean b = file.createNewFile(); //returns false, indicating the file wasn't made
                    text.setText(text.getText()+String.valueOf(b));
                    new File(getFilesDir().getAbsolutePath()).mkdirs();
                    FileWriter write = new FileWriter(getFilesDir().toString()+File.pathSeparator+"updater-script");
                    Show(getFilesDir().toString());
                    write.write(aa);
                    write.close();
                } catch (Exception e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
                }
        });
        B2.setOnLongClickListener(new View.OnLongClickListener() {

            @Override
            public boolean onLongClick(View v) {
                File file = new File(getFilesDir(), "updater-script");
                try {
                    FileInputStream in = new FileInputStream(file);
                    String aa = inputStreamToString(in);
                    text.setText(aa);
                } catch (FileNotFoundException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }


                return true;
            }
        });

我的 list :

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="seaskyways.testingproject"
    android:versionCode="1"
    android:versionName="beta" >

    <uses-sdk
        android:minSdkVersion="14"
        android:targetSdkVersion="17" />

    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STROAGE"/>
    <uses-permission android:name="android.permission.WRITE_INTERNAL_STORAGE"/>

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/Theme.Sherlock" >
        <activity
            android:name="seaskyways.testingproject.MainActivity"
            android:label="@string/app_name"
            android:screenOrientation="portrait"
            android:theme="@android:style/Theme.Holo"
            android:uiOptions="splitActionBarWhenNarrow" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity
            android:name="seaskyways.testingproject.MenuActivity"
            android:label="@string/title_activity_menu" >
        </activity>
        <activity
            android:name="seaskyways.testingproject.Splash"
            android:label="@string/title_activity_splash"
            android:theme="@style/Theme.Sherlock.Dialog" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.DEFAULT" />
            </intent-filter>
        </activity>
        <activity
            android:name="seaskyways.testingproject.HorizontalScrollView"
            android:label="@string/title_activity_splash" >
            <intent-filter>
                <action android:name="android.intent.action.HSV" />

                <category android:name="android.intent.category.DEFAULT" />
            </intent-filter>
        </activity>
        <activity
            android:name="seaskyways.testingproject.ExpandableLists"
            android:label="@string/title_activity_expandable_lists"
            android:parentActivityName="seaskyways.testingproject.MainActivity" >
            <meta-data
                android:name="android.support.PARENT_ACTIVITY"
                android:value="seaskyways.testingproject.MainActivity" />
        </activity>
        <activity
            android:name="seaskyways.testingproject.SwipeStrips"
            android:label="@string/title_activity_swipe_tabs"
            android:parentActivityName="seaskyways.testingproject.MainActivity" >
            <meta-data
                android:name="android.support.PARENT_ACTIVITY"
                android:value="seaskyways.testingproject.MainActivity" />
        </activity>
        <activity
            android:name="seaskyways.testingproject.SwipeTabs"
            android:label="@string/title_activity_swipe_tabs"
            android:parentActivityName="seaskyways.testingproject.MainActivity" >
            <meta-data
                android:name="android.support.PARENT_ACTIVITY"
                android:value="seaskyways.testingproject.MainActivity" />
        </activity>
    </application>

</manifest>

堆栈跟踪:

03-11 21:23:08.241: E/AndroidRuntime(3958): FATAL EXCEPTION: main
03-11 21:23:08.241: E/AndroidRuntime(3958): java.util.NoSuchElementException
03-11 21:23:08.241: E/AndroidRuntime(3958):     at java.util.Scanner.next(Scanner.java:1007)
03-11 21:23:08.241: E/AndroidRuntime(3958):     at java.util.Scanner.next(Scanner.java:980)
03-11 21:23:08.241: E/AndroidRuntime(3958):     at seaskyways.testingproject.MainActivity.inputStreamToString(MainActivity.java:44)
03-11 21:23:08.241: E/AndroidRuntime(3958):     at seaskyways.testingproject.MainActivity$7.onLongClick(MainActivity.java:171)
03-11 21:23:08.241: E/AndroidRuntime(3958):     at android.view.View.performLongClick(View.java:4240)
03-11 21:23:08.241: E/AndroidRuntime(3958):     at android.widget.TextView.performLongClick(TextView.java:8060)
03-11 21:23:08.241: E/AndroidRuntime(3958):     at android.view.View$CheckForLongPress.run(View.java:17339)
03-11 21:23:08.241: E/AndroidRuntime(3958):     at android.os.Handler.handleCallback(Handler.java:725)
03-11 21:23:08.241: E/AndroidRuntime(3958):     at android.os.Handler.dispatchMessage(Handler.java:92)
03-11 21:23:08.241: E/AndroidRuntime(3958):     at android.os.Looper.loop(Looper.java:137)
03-11 21:23:08.241: E/AndroidRuntime(3958):     at android.app.ActivityThread.main(ActivityThread.java:5237)
03-11 21:23:08.241: E/AndroidRuntime(3958):     at java.lang.reflect.Method.invokeNative(Native Method)
03-11 21:23:08.241: E/AndroidRuntime(3958):     at java.lang.reflect.Method.invoke(Method.java:511)
03-11 21:23:08.241: E/AndroidRuntime(3958):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:799)
03-11 21:23:08.241: E/AndroidRuntime(3958):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:566)
03-11 21:23:08.241: E/AndroidRuntime(3958):     at dalvik.system.NativeStart.main(Native Method)

请不要有变通办法，因为我有 future 的计划...感谢您的帮助!如果您需要更多信息，请点击此处，评论框向下几厘米:P

Answer 1

来自 this documentation我知道您实际上应该使用 .hasNext() 保护您的 .next() 调用.

这里，例如:

public String inputStreamToString(InputStream stream){

    Scanner s = new Scanner(stream).useDelimiter("\\A");
    if (s.hasNext()){
       return s.next();
    }else{
       return null;
    }       
}

而且，如果你的权限写对了，这个

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STROAGE"/>

权限实际上并不存在。应该是

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>