Error when Changing to targetSdkVersion 26 from targetSdkVersion 21

Question

latly I changed to targetSdkVersion 26 from targetSdkVersion 21. By doing so several issues arise.

1. I have written a class and run but gose to throw new RuntimeException(e)

   The code is as follows

   package com.xxxxxxxxxx.android.webapp.util;
   
   import android.content.Context;
   import android.telephony.TelephonyManager;
   
   import com.xxxxxxxxxx.android.webapp.BuildConfig;
   
   import java.io.File;
   import java.io.FileOutputStream;
   import java.io.IOException;
   import java.io.RandomAccessFile;
   import java.security.MessageDigest;
   import java.security.NoSuchAlgorithmException;
   
   
   public class Installation {
   private static String sID = null;
   private static final String INSTALLATION = "INSTALLATION";
   
   public synchronized static String id(Context context) {
       if (sID == null) {
           File installation = new File(context.getFilesDir(), INSTALLATION);
           try {
               if (!installation.exists())
                   writeInstallationFile(installation,context);
               sID = readInstallationFile(installation,context);
           } catch (Exception e) {
               throw new RuntimeException(e);
           }
       }
       return sID;
   }
   
   private static String readInstallationFile(File installation,Context context) throws IOException {
       RandomAccessFile f = new RandomAccessFile(installation, "r");
       byte[] bytes = new byte[(int) f.length()];
       f.readFully(bytes);
       f.close();
       return new String(bytes);
   }
   
   private static void writeInstallationFile(File installation,Context context) throws IOException {
       FileOutputStream out = new FileOutputStream(installation);
       String id = getUniqueID(context);   //UUID.randomUUID().toString();
       out.write(id.getBytes());
       out.close();
   }
   
   private static String getUniqueID(Context context){
       String android_id = android.provider.Settings.Secure.getString(
               context.getContentResolver(), android.provider.Settings.Secure.ANDROID_ID);
   
       String eid = null;
       try {
           eid = Encryptor.encrypt("gignoGawaAppli", android_id );
   
           if (BuildConfig.uidEncryptionMd5) {
               eid = md5(eid);
           }
   
       }catch (Exception e){};
       return eid;
   }
   
   public static String md5(String s) {
       try {
           // Create MD5 Hash
           MessageDigest digest = java.security.MessageDigest.getInstance("MD5");
           digest.update(s.getBytes());
           byte messageDigest[] = digest.digest();
   
           // Create Hex String
           StringBuffer hexString = new StringBuffer();
           for (int i = 0; i < messageDigest.length; i++) {
               if ((0xff & messageDigest[i]) < 0x10) {
                   hexString.append("0" + Integer.toHexString((0xFF & messageDigest[i])));
               } else {
                   hexString.append(Integer.toHexString(0xFF & messageDigest[i]));
               }
           }
           return hexString.toString();
   
       } catch (NoSuchAlgorithmException e) {
           e.printStackTrace();
       }
       return "";
   }
   
   }
   

appeard on the console like this

Caused by: java.lang.RuntimeException: java.lang.NullPointerException: Attempt to invoke virtual method byte[] java.lang.String.getBytes() on a null object reference

2. cant get ANDROID_ID

   when my project targetSdkVersion's 21 everthing is ok.

Please help thank you very much.

Answer 1

May be the issue is you don't provide run time permissions.Here is the tutorial

Answer 2

「Caused by: java.lang.RuntimeException: java.lang.NullPointerException: Attempt to invoke virtual method 'byte[] java.lang.String.getBytes()' on a null object reference」

This is because below code

String id = getUniqueID(context);   //UUID.randomUUID().toString(); 

returns a null pointer, which means method getUniqueID is not executed correctly. You need to debug this method to get more details.