Getpreferences不能在片段中工作

findViewByIdgetSharedPreferences命令不工作内部Fragment我正在使用kotlin,我的代码如下

 fun update (v:View){ Val sharedpref = getSharedPreferences("logindata",Context.MODE_PRIVATE)} 

LOG

 E/AndroidRuntime: FATAL EXCEPTION: main Process: com.techno.app, PID: 25691 java.lang.IllegalStateException: Could not find method update(View) in a parent or ancestor Context for android:onClick attribute defined on view class android.support.v7.widget.AppCompatButton at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.resolveMethod(AppCompatViewInflater.java:327) at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:284) at android.view.View.performClick(View.java:5721) at android.widget.TextView.performClick(TextView.java:10936) at android.view.View$PerformClick.run(View.java:22620) at android.os.Handler.handleCallback(Handler.java:739) 

你的概念明智的上述答案( https://stackoverflow.com/a/44469679/3845798 )是正确的,但它需要在Kotlin。 像getActivity()getView()将像一个属性一样访问。 另外,它的val不是Val

下面是如何在活动中使用findViewById()getSharedPreferences()简单示例。

主活动代码 –

 class MainActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) setBaseFragment() } private fun setBaseFragment() { val fragment = MainFragment.newInstance() supportFragmentManager .beginTransaction() .replace(R.id.fragment_container, fragment) .commit() } } 

这是我的片段类

 class MainFragment : Fragment() { lateinit var show: Button lateinit var save: Button lateinit var text: TextView var prefs: SharedPreferences? = null override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) } override fun onCreateView(inflater: LayoutInflater?, container: ViewGroup?, savedInstanceState: Bundle?): View? { return inflater!!.inflate(R.layout.fragment_main, container, false) } override fun onViewCreated(view: View?, savedInstanceState: Bundle?) { super.onViewCreated(view, savedInstanceState) show = view?.findViewById(R.id.showButton) as Button save = view?.findViewById(R.id.saveButton) as Button text = view?.findViewById(R.id.textResult) as TextView prefs = activity.getSharedPreferences("FUN",MODE_PRIVATE) save.setOnClickListener { val editor = prefs!!.edit() editor.putString("Saving", "This is saveValueFromSharedPref") editor.apply() } show.setOnClickListener { text.setText(prefs?.getString("Saving","NotSaved")) } } companion object { fun newInstance(): MainFragment { val fragment = MainFragment() return fragment } } } 

这是一个简单的例子,有一个文本和两个按钮。

首先你必须保存和显示。

另外,对于您的应用程序崩溃,您可以检查此解决方案

你在Fragment中调用一个Context对象,Fragment不是一个Context把这行改成这样:

 Val sharedpref = getActivity().getSharedPreferences("logindata",Context.MODE_PRIVATE)} 

并且使用findViewByIdonCreateView使用getView方法,例如:

 TextView tv = (TextView) getView().findViewById(R.id.mtTextview);