Question

我的申请使用SD卡的数据目录储存档案。开始时,如果该名录已经存在,则该名录便可创建。出于某种原因,这在我所设立的不同的DVD基础上进行,但我如果把决议定在QVGA的话,可以不这样做。

该法典正在流产:

File root = new File("/sdcard/mydir");
if(!root.exists()) {
  try {
    root.mkdir();
  }
  catch...

mkdir()正在回落假。

任何想法为什么?

Answer 1

我忘记在我的发言中加上SD卡的许可:

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

Without the permission the program worked on all emulators except QVGA, and even on my Droid.

Answer 2

在制作QVGA DVD时,你可能放弃建立SD卡。重新设置。

此外,您不应成为外部储存的硬编码途径:。某些亚特兰大公司可以进入外部储存。

The following snippet might detect some issues with mounting.

boolean mExternalStorageAvailable = false;
boolean mExternalStorageWriteable = false;
String state = Environment.getExternalStorageState();

if (Environment.MEDIA_MOUNTED.equals(state)) {
    // We can read and write the media
    mExternalStorageAvailable = mExternalStorageWriteable = true;
} else if (Environment.MEDIA_MOUNTED_READ_ONLY.equals(state)) {
    // We can only read the media
    mExternalStorageAvailable = true;
    mExternalStorageWriteable = false;
} else {
    // Something else is wrong. It may be one of many other states, but all we need
    //  to know is we can neither read nor write
    mExternalStorageAvailable = mExternalStorageWriteable = false;
}

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