Question

我发布了一个应用程序，我需要将一些hunderd kb size ogg文件复制到用户的SD卡上。很快我收到了错误报告。就我而言，问题可能是因为该路径不适合该特定电话：

String path = "/sdcard/file.ogg"; 

            File file = new File(Environment.getExternalStorageDirectory(), "file.ogg" );
            if (!file.exists()) {


                InputStream in = getResources().openRawResource(R.raw.file);
                FileOutputStream out = null;
                try {
                    out = new FileOutputStream(path);
                } catch (FileNotFoundException e1) {
                    // TODO Auto-generated catch block
                    e1.printStackTrace();
                }
                byte[] buff = new byte[1024];
                int read = 0;

                try {
                    while ((read = in.read(buff)) > 0) {
                        out.write(buff, 0, read);
                    }
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                } finally {
                    try {
                        in.close();
                    } catch (IOException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }

                    try {
                        out.close();
                    } catch (IOException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }
                }

所以报告是：

java.lang.RuntimeException: Unable to start activity ComponentInfo{com.caodeveloping.androgangnam/com.caodeveloping.androgangnam.Main}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1659)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1675)
at android.app.ActivityThread.access$1500(ActivityThread.java:121)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:943)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:130)
at android.app.ActivityThread.main(ActivityThread.java:3701)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:507)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:624)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.caodeveloping.androgangnam.Main.onCreate(Main.java:388)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1623)
... 11 more

第388行是out.close（）;是否有可能/ sdcard /不适合该手机上的路径？什么可能导致这个？提前谢谢！

更新，这个？

String path= Environment.getExternalStorageDirectory().getAbsolutePath();
path += "/file.ogg";

Answer 1

两个问题：

a）显然，如果你无法打开它，你试图关闭文件（out.close（）），事件

b）我建议使用Environment.getExternalStorageDirectory（），而不是硬编码目录名“/ sdcard”。无法保证将SD卡安装到此路径。这正是Environment.getExternalStorageDirectory（）API的原因。

另外，我建议查看整个代码以进行错误处理（如果无法打开，读取等内容）

尝试向sdcard添加路径时出现Nullpointer异常

1 个答案: