fragment_display_message:我的第一个Android应用程序错误

Question

我是第一次开发移动应用程序

环境:Eclipse Kepler,Java 1.7后端:

我按照以下步骤操作:

1)安装Android SDK并运行Android SDK Manager,并安装所需的文件

2)安装的ADT Eclipse ADT插件:https://dl-ssl.google.com/android/eclipse

在一些标准文档的这个阶段,它说你必须现在创建一个AVD,AVD图标被假设出现在我的工具栏中,但我无法在任何地方找到它.

现在,我正在尝试开发我的第一个应用程序,如本网站所示:http://developer.android.com/training/basics/firstapp/index.html

我正在添加我的代码片段,如下所示:

main.xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
</LinearLayout>

strings.xml:

<?xml version="1.0" encoding="utf-8"?>
<resources>
<string name="app_name">My First App</string>
<string name="edit_message">Enter a message</string>
<string name="button_send">Send</string>
<string name="action_settings">Settings</string>
<string name="title_activity_main">MainActivity</string>
<string name="uploading">Uploading…</string>
<string name="hello_world">Hello world!</string>
<string name="title_activity_display_message">DisplayMessageActivity</string>
</resources>

AndroidManifest.xml:

<!--  <?xml version="1.0" encoding="utf-8" standalone="no"?> -->
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.amazon.demo"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
    android:minSdkVersion="16" 
    android:targetSdkVersion ="20" />
<uses-permission android:name="android.permission.INTERNET" />
<application
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name" 
    android:allowBackup="true" >      
    <activity
        android:name=".MainActivity"
        android:label="@string/title_activity_main" >
    </activity>
    <activity
        android:name=".DisplayMessageActivity"
        android:label="@string/title_activity_display_message"
        android:parentActivityName="com.amazon.demo.MainActivity" >
        <meta-data
            android:name="android.support.PARENT_ACTIVITY"
            android:value="com.amazon.demo.MainActivity" />
    </activity>        
</application>    
</manifest>

MainActivity.java

public class MainActivity extends ActionBarActivity {   
public final static String EXTRA_MESSAGE = "com.amazon.demo.MESSAGE";
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();
    if (id == R.id.action_settings) {
        return true;
    }
    return super.onOptionsItemSelected(item);
}   
public void sendMessage(View view) {
     Intent intent = new Intent(this, DisplayMessageActivity.class);
        EditText editText = (EditText) findViewById(R.id.edit_message);
        String message = editText.getText().toString();
        intent.putExtra(EXTRA_MESSAGE, message);
        startActivity(intent);
}   
}

activity_main.xml:

<LinearLayout 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:orientation="horizontal" 
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.amazon.demo.MainActivity" >
 <EditText android:id="@+id/edit_message"
    android:layout_width="0dp"
    android:layout_height="wrap_content"
    android:layout_weight="1"
    android:hint="@string/edit_message" />
 <Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/button_send"
    android:onClick="sendMessage" />
</LinearLayout>

DisplayMessageActivity.java:

public class DisplayMessageActivity extends ActionBarActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    //setContentView(R.layout.activity_display_message);
    // Get the message from the intent
    Intent intent = getIntent();
    String message = intent.getStringExtra(MainActivity.EXTRA_MESSAGE);
    // Create the text view
    TextView textView = new TextView(this);
    textView.setTextSize(40);
    textView.setText(message);
    // Set the text view as the activity layout
    setContentView(textView);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.display_message, menu);
    return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();
    if (id == R.id.action_settings) {
        return true;
    }
    return super.onOptionsItemSelected(item);
}   
public static class PlaceholderFragment extends Fragment {
    public PlaceholderFragment() { }
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
             Bundle savedInstanceState) {
          View rootView = inflater.inflate(R.layout.fragment_display_message,container, false);
          return rootView;
   }
}
}

activity_display_message.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:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.amazon.demo.DisplayMessageActivity" >
<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/hello_world" />
</RelativeLayout>

现在不像我的第一个应用程序崩溃时按下按钮我在我的项目目录中的任何地方都有fragment_main.xml和fragment_display_message.xml.这两个文件是自己创建的吗？或者我们是否必须单独创建它们？

我是否还安装了正确开发Android应用程序的所有先决条件？我不确定.

另外,在DisplayMessageActivity.java中它表示:fragment_display_message无法解析或不是字段

因此我也无法运行该文件.

请帮忙.和长期描述的sry.

Answer 1

我刚刚解决了同样的问题,它仍然存在于ANDROID-STUDIO 构建您的第一个应用教程中.

在DisplayMessageActivity.java中,我替换R.layout.fragment_display_message为R.layout.activity_display_message.这引用了activity_display_message.xml多余的内容.

您不必创建新的fragment_display_message.xml.