我是Android开发的新手。尝试清除与editor.clear（）;的登录会话时出现此错误
这是为了使用SharedPreferences.Editor清除登录会话
public void logout() {
editor.clear();
editor.commit();
Intent login = new Intent(context, AccountLoginPage.class);
context.startActivity(login);
((HomePage) context).finish();
}
完整代码：
public class SessionHandler {
SharedPreferences sharedPreferences;
public SharedPreferences.Editor editor;
public Context context;
int PRIVATE_MODE = 0;
private static final String PREF_NAME = "LOGIN";
private static final String LOGIN = "IS_LOGIN";
public static final String EMAIL = "EMAIL";
public static final String PASSWORD = "PASSWORD";
public SessionHandler(Context context) {
this.context = context;
sharedPreferences = context.getSharedPreferences(PREF_NAME, PRIVATE_MODE);
}
public void createSession(String email, String password) {
editor.putString(LOGIN, "IS_LOGIN");
editor.putString(EMAIL, email);
editor.putString(PASSWORD, password);
editor.apply();
}
public boolean isLogin() {
return sharedPreferences.getBoolean(LOGIN, false);
}
public void checkLogin() {
if (this.isLogin()) {
Intent login = new Intent(context, AccountLoginPage.class);
context.startActivity(login);
((HomePage) context).finish();
}
}
public HashMap<String, String> getUserDetail(){
HashMap<String, String> user = new HashMap<>();
user.put(EMAIL, sharedPreferences.getString(EMAIL, null));
user.put(PASSWORD, sharedPreferences.getString(PASSWORD, null));
return user;
}
public void logout() {
editor.clear();
editor.commit();
Intent login = new Intent(context, AccountLoginPage.class);
context.startActivity(login);
((HomePage) context).finish();
}
public String getEmail() {
return EMAIL;
}
}
日志：
Caused by: java.lang.NullPointerException: Attempt to invoke interface method 'android.content.SharedPreferences$Editor android.content.SharedPreferences$Editor.clear()' on a null object reference