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我的ApkInfo活動應該顯示權限以及權限描述。但是在運行期間，它會以未知格式顯示權限說明。在下面的代碼中，AppData類用於初始化packageInfo，用戶從已安裝的應用程序列表中填充用戶選擇的應用程序。檢索權限描述時出錯
public class ApkInfo extends Activity {
PackageInfo packageInfo;
PermissionInfo pi;
PackageManager pm;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.apkinfo);
PermissionInfo pi = new PermissionInfo();
AppData appData = (AppData) getApplicationContext();
packageInfo = appData.getPackageInfo();
if (packageInfo.requestedPermissions != null){
String[] permissions = getPermissions(packageInfo.requestedPermissions, pi);
}
private String[] getPermissions(String[] requestedPermissions, PermissionInfo pinfo) {
pm = getPackageManager();
String permission = "";
for (int i = 0; i < requestedPermissions.length; i++) {
try {
pinfo = pm.getPermissionInfo(requestedPermissions[i], PackageManager.GET_META_DATA);
try {
pinfo.loadDescription(pm).toString();
}catch(NullPointerException ex){
ex.printStackTrace();
}finally{
Log.d("Permissions description", "Null");
}
} catch (NameNotFoundException e) {
e.printStackTrace();
}
permission = permission + requestedPermissions[i] + " " + pinfo + "\n";
Log.d("PERMISSIONS" , pm.toString());
}
String lines[] = permission.split("\\n");
return lines;
}
}
這裏是我的logcat輸出：
06-25 11:35:00.741: D/Permissions description(776): Null
06-25 11:35:00.741: D/PERMISSION DESCRIPTION(776): PermissionInfo{40da5f10 android.permission.CAMERA}
06-25 11:35:00.754: W/System.err(776): java.lang.NullPointerException
06-25 11:35:00.781: W/System.err(776): at com.ibc.android.demo.appslist.activity.ApkInfo.getPermissions(ApkInfo.java:54)
06-25 11:35:00.781: W/System.err(776): at com.ibc.android.demo.appslist.activity.ApkInfo.onCreate(ApkInfo.java:34)
06-25 11:35:00.781: W/System.err(776): at android.app.Activity.performCreate(Activity.java:5104)
06-25 11:35:00.793: W/System.err(776): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
06-25 11:35:00.793: W/System.err(776): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
06-25 11:35:00.812: W/System.err(776): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
06-25 11:35:00.812: W/System.err(776): at android.app.ActivityThread.access$600(ActivityThread.java:141)
06-25 11:35:00.812: W/System.err(776): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
06-25 11:35:00.821: W/System.err(776): at android.os.Handler.dispatchMessage(Handler.java:99)
06-25 11:35:00.821: W/System.err(776): at android.os.Looper.loop(Looper.java:137)
06-25 11:35:00.831: W/System.err(776): at android.app.ActivityThread.main(ActivityThread.java:5041)
06-25 11:35:00.841: W/System.err(776): at java.lang.reflect.Method.invokeNative(Native Method)
06-25 11:35:00.841: W/System.err(776): at java.lang.reflect.Method.invoke(Method.java:511)
06-25 11:35:00.851: W/System.err(776): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
06-25 11:35:00.851: W/System.err(776): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
06-25 11:35:00.851: W/System.err(776): at dalvik.system.NativeStart.main(Native Method)
06-25 11:35:00.861: D/Permissions description(776): Null
06-25 11:35:00.861: D/PERMISSION DESCRIPTION(776): PermissionInfo{40da7378 android.permission.RECORD_AUDIO}
06-25 11:35:00.891: D/Permissions description(776): Null
06-25 11:35:00.891: D/PERMISSION DESCRIPTION(776): PermissionInfo{40daa998 android.permission.ACCESS_FINE_LOCATION}
06-25 11:35:00.931: D/Permissions description(776): Null
06-25 11:35:00.931: D/PERMISSION DESCRIPTION(776): PermissionInfo{40dab3b8 android.permission.WAKE_LOCK}
06-25 11:35:00.964: D/Permissions description(776): Null
06-25 11:35:00.964: D/PERMISSION DESCRIPTION(776): PermissionInfo{40dabf28 android.permission.SET_WALLPAPER}
06-25 11:35:00.991: D/Permissions description(776): Null
06-25 11:35:00.991: D/PERMISSION DESCRIPTION(776): PermissionInfo{40dacaa8 android.permission.WRITE_EXTERNAL_STORAGE}
06-25 11:35:01.021: D/Permissions description(776): Null
06-25 11:35:01.021: D/PERMISSION DESCRIPTION(776): PermissionInfo{40dad588 android.permission.READ_SMS}
06-25 11:35:01.041: D/Permissions description(776): Null
06-25 11:35:01.041: D/PERMISSION DESCRIPTION(776): PermissionInfo{40dae020 android.permission.READ_EXTERNAL_STORAGE}
爲什麼我ApkInfo活動以這樣的方式顯示許可說明？對於某些應用程序，它顯示一個NullPointerException。