[error] java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.SharedPreferences android.content.Context.getSharedPreferences(java.lang.String, int)' on a null object reference

java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.SharedPreferences android.content.Context.getSharedPreferences(java.lang.String, int)' on a null object reference

 

 

위에러 해결법.

혹시, 다음과 같이 외부  class에 적용해 두었다면...

꼭 확인 해 볼 것.

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<code>public class SettingData {     public static SettingData singleTon;     private Context context;     private SharedPreferences appData;       private SettingData()     {         context = MainActivity.context;         appData = context.getSharedPreferences("hybrid", MODE_PRIVATE);     }       public static SettingData getInstance()     {         if(singleTon == null)             singleTon = new SettingData();           return singleTon;     }       //     public String getServerURL()     {             String result = appData.getString("Server", "192.168.18.13");         return result;     }       public void setServerURL(String url)     {         SharedPreferences.Editor editor = appData.edit();         editor.putString("Server", url);         //editor.putInt("ServerPos", 1);         editor.apply();     } } </code>

MainActivity.context에 값을 할당 했는지 체크해 볼 것.

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<code>public class MainActivity extends AppCompatActivity {     public static Context context;     protected EditText etUrl;       @Override     protected void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.activity_main);           context = getApplicationContext();    /////////////이 부분     }       ...... </code>

 

할당을 안해서... 하루를 버림.