我使用的靜態類,你可以在這裏找到, ,但由於某種原因,當我使用類getEmail(){...方法I獲取異常:Java的Android - 靜態類中的私人構造函數不會被調用
java.lang.RuntimeException:無法啓動活動ComponentInfo {com.techsolutions.appgrade/com.techsolutions.appgrade.View.RegisterActivity}:java.lang.NullPointerException:試圖調用接口方法boolean android .content.SharedPreferences.contains(java.lang.String)'on null object引用
它看起來像私人構造函數沒有得到調用編輯。
這是我的靜態類:
package com.techsolutions.appgrade.Logic;
import android.app.Activity;
import android.app.Application;
import android.content.Context;
import android.content.SharedPreferences;
import org.apache.commons.validator.routines.EmailValidator;
public final class DataController extends Application{
private static SharedPreferences sharedPref;
private static SharedPreferences.Editor editor;
private static Context context;
private static boolean isRegistered;
private static String PREF_NAME = "StudentSharedPref";
private static String KEY_Name = "name";
private static String KEY_Email = "email";
private static String KEY_PhoneNum = "phoneNum";
private static String KEY_Age = "age";
private static String KEY_Realm = "age";
public static DataController instance;
private DataController()
{
System.out.println("Been HERE");
sharedPref = context.getSharedPreferences(PREF_NAME, Activity.MODE_PRIVATE);
editor = sharedPref.edit();
context = getApplicationContext();
isRegistered = false;
}
public static void setName(String name)
{
editor.putString(KEY_Name, name);
editor.apply();
}
public static String getName(){
if(sharedPref.contains(KEY_Name))
{
return sharedPref.getString(KEY_Name, "");
}
return "";
}
public static boolean setEmail(String email)
{
if(!EmailValidator.getInstance().isValid(email))
return false;
editor.putString(KEY_Email, email);
editor.apply();
return true;
}
public static String getEmail(){
if(sharedPref.contains(KEY_Email))
{
return sharedPref.getString(KEY_Email, "");
}
return "";
}
public static boolean setPhonNum(String phoneNum)
{
if(String.valueOf(phoneNum).length() == 10)
return false;
editor.putString(KEY_PhoneNum, phoneNum);
editor.apply();
return true;
}
public static String getPhoneNum(){
if(sharedPref.contains(KEY_PhoneNum))
{
return sharedPref.getString(KEY_PhoneNum, "");
}
return "";
}
public static boolean setAge(int age)
{
if(age <= 0 || age>120)
return false;
editor.putInt(KEY_Age, age);
editor.apply();
return true;
}
public static String getAge(){
if(sharedPref.contains(KEY_Age))
{
return sharedPref.getString(KEY_Age, "");
}
return "";
}
public static void setRealm(String realm)
{
editor.putString(KEY_Realm, realm);
editor.apply();
}
public static String getRealm(){
if(sharedPref.contains(KEY_Realm))
{
return sharedPref.getString(KEY_Realm, "");
}
return "";
}
}
,這是我怎麼叫從另一個類中的方法:
DataController.setEmail(email)
示例中沒有顯示靜態類。 –