Android 您能否在一个程序中启动另一个活动两次？

我正在尝试使用android studio培训创建我自己的项目。此问题是无法解决额外的_消息符号。我需要帮助纠正错误

错误 错误：（21，60）错误：找不到符号变量EXTRA_消息 错误：（20，70）错误：找不到符号变量EXTRA_消息 C:\Users\Michael Jr\Desktop\Final\app\src\main\java\mike\affinal\DisplayMessageActivity.java C:\Users\Michael Jr\Desktop\Final\app\src\main\java\mike\affinal\DisplayMessageActivity2.java 信息：渐变任务[：app:clean，：app:generatedebugandroidsources，：app:mockableAndroidJar，：app:prepareDebugUnitTestDependencies，：app:generateDebugAndroidTestSources，：app:assembleDebug] 错误：任务“：app:compiledBugJavaWithJavaC”的执行失败

编译失败；有关详细信息，请参阅编译器错误输出

我的雄激素清单

     <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity android:name=".DisplayMessageActivity" />
        <activity android:name=".DisplayMessageActivity2"></activity>
    </application>

</manifest>

我的DisplayMessageActvity2

   package mike.afinal;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.ViewGroup;
import android.widget.TextView;

import static android.provider.AlarmClock.EXTRA_MESSAGE;

public class DisplayMessageActivity2 extends AppCompatActivity {


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_display_message2);

        Intent intent = getIntent();
        String message = intent.getStringExtra(DisplayMessageActivity.EXTRA_MESSAGE);
        TextView textView = new TextView(this);
        textView.setTextSize(40);
        textView.setText(message);

        ViewGroup layout = (ViewGroup) findViewById(R.id.activity_display_message2);
        layout.addView(textView);
    }
}

My activity_main.xml

<TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="15dp"
        android:textColor ="#FF0"
        android:text=" I added a black backround to better the contrast."
        android:id="@+id/textView"
        android:layout_alignParentBottom="true"
        android:layout_alignParentRight="true"
        android:layout_alignParentEnd="true"
        android:layout_marginBottom="47dp"
        tools:ignore="DuplicateIds" />

    <Button
        android:text="Toast Example"
        android:onClick="onClick"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/button2"
        android:layout_marginBottom="86dp"
        android:layout_above="@+id/textView"
        android:layout_alignParentRight="false"
        android:layout_alignParentEnd="false" />

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/button_send"
        android:onClick="sendMessage"
        android:layout_marginRight="24dp"
        android:layout_marginEnd="24dp"
        android:layout_above="@+id/button2"
        android:layout_alignParentRight="true"
        android:layout_alignParentEnd="true"
        android:layout_marginBottom="100dp" />

</RelativeLayout>

我的活动显示消息.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_display_message"
    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"
    android:background="#000"
    tools:context="mike.afinal.DisplayMessageActivity">

    <EditText android:id="@+id/edit_message"
        android:textColor ="#FF0"
        android:layout_weight="1"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:hint="@string/edit_message" />

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/button_send"
        android:onClick="sendMessage"
        android:layout_marginRight="24dp"
        android:layout_marginEnd="24dp"
        android:layout_above="@+id/button2"
        android:layout_alignParentRight="true"
        android:layout_alignParentEnd="true"
        android:layout_marginBottom="100dp" />

我的活动显示消息2.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_display_message2"
    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="mike.afinal.DisplayMessageActivity2">

</RelativeLayout>

My strings.xml

<resources>
    <string name="app_name">Final Project</string>
    <string name="edit_message">Enter a message</string>
    <string name="button_send">Start new activity</string>
</resources>

最终项目
输入消息
开始新的活动

我在

MainActivity

中没有看到

额外消息的定义。此外，我认为您意外地执行了
静态导入AlarmManager.EXTRA_MESSAGE
。我在
MainActivity
中没有看到
EXTRA_MESSAGE
的定义。此外，我认为您意外地执行了一个
静态导入AlarmManager.EXTRA_MESSAGE
。
<resources>
    <string name="app_name">Final Project</string>
    <string name="edit_message">Enter a message</string>
    <string name="button_send">Start new activity</string>
</resources>