在单击按钮并在 TextView 中显示时读取编辑文本内容时出错 [重复]

Question

我正在导航抽屉菜单中实现一个片段。我想在单击按钮时阅读编辑文本的内容并在文本视图中显示阅读的内容。但是，我收到以下错误： java.lang.NullPointerException: 尝试调用虚拟方法'android.view.View android.view.View

片段类：

public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {

    editText = (EditText) getView().findViewById(R.id.id_editText);
    button = (Button) getView().findViewById(R.id.id_button);
    textView = (TextView) getView().findViewById(R.id.id_textView);
    button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            String Name = editText.getText().toString();
            textView.setText(Name);
        }
    });

    return inflater.inflate(R.layout.fragment_chat, container, false);

}

片段 xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#566D7E"
tools:context="com.example.jr.mybluetoothchat.ChatFragment">


<EditText
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:inputType="textPersonName"
    android:text="Enter Text"
    android:ems="10"
    android:layout_alignParentTop="true"
    android:layout_centerHorizontal="true"
    android:layout_marginTop="90dp"
    android:id="@+id/id_editText" />

<Button
    android:text="Click"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@+id/id_editText"
    android:layout_centerHorizontal="true"
    android:layout_marginTop="43dp"
    android:id="@+id/id_button" />

<TextView
    android:text="Entered Text"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@+id/id_button"
    android:layout_alignStart="@+id/id_editText"
    android:layout_marginStart="43dp"
    android:layout_marginTop="91dp"
    android:id="@+id/id_textView" />

内容主 xml

    <?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/id_content_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#BCC6CC"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:context="com.example.jr.mybluetoothchat.MainActivity"
    tools:showIn="@layout/app_bar_main">


</RelativeLayout>

主要活动

public boolean onNavigationItemSelected(MenuItem item) {
        // Handle navigation view item clicks here.
        int id = item.getItemId();

        if (id == R.id.nav_home)
        {
            Toast.makeText(this,"Home",Toast.LENGTH_SHORT).show();
        } else if (id == R.id.nav_chat)
        {
            Toast.makeText(this,"Chat",Toast.LENGTH_SHORT).show();
            FragmentManager fragmentManager = getSupportFragmentManager();
            FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
            ChatFragment chatFragment = new ChatFragment();
            fragmentTransaction.replace(R.id.id_content_main,chatFragment);
            fragmentTransaction.commit();
        } else if (id == R.id.nav_invite)
        {
            Toast.makeText(this,"Invite",Toast.LENGTH_SHORT).show();
        }

        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        drawer.closeDrawer(GravityCompat.START);
        return true;
    }

Answer 1

更改您的此代码

public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {

    editText = (EditText) getView().findViewById(R.id.id_editText);
    button = (Button) getView().findViewById(R.id.id_button);
    textView = (TextView) getView().findViewById(R.id.id_textView);
    button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            String Name = editText.getText().toString();
            textView.setText(Name);
        }
    });

    return inflater.inflate(R.layout.fragment_chat, container, false);

}

到这里

public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {

    View view = inflater.inflate(R.layout.fragment_chat, container, false);
    editText = (EditText) view.findViewById(R.id.id_editText);
    button = (Button) view.findViewById(R.id.id_button);
    textView = (TextView) view.findViewById(R.id.id_textView);
    button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            String Name = editText.getText().toString();
            textView.setText(Name);
        }
    });

    return view;

}