Question

我正在尝试使用android studio培训来创建我自己的项目。此问题是Extra_MESSAGE符号无法解析。我需要帮助修复错误。

错误错误：（21,60）错误：找不到符号变量EXTRA_MESSAGE 错误：（20,70）错误：找不到符号变量EXTRA_MESSAGE C：\ Users \ Michael Jr \ Desktop \ Final \ app \ src \ main \ java \ mike \ afinal \ DisplayMessageActivity.java C：\ Users \ Michael Jr \ Desktop \ Final \ app \ src \ main \ java \ mike \ afinal \ DisplayMessageActivity2.java 信息：Gradle任务[：app：clean，：app：generateDebugSources，：app：mockableAndroidJar，：app：prepareDebugUnitTestDependencies，：app：generateDebugAndroidTestSources，：app：assembleDebug] 错误：任务'：app：compileDebugJavaWithJavac'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AndroidManifest

     <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>

我的主要活动

      public class MainActivity extends AppCompatActivity {

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

    public void onClick (View view) {
        Toast.makeText(this, "Button 1 pressed",
                Toast.LENGTH_LONG).show();
    }

    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);
    }


    }


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

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

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

        /** Called when the user clicks the Send button */
        public void sendMessage(View view) {
            Intent intent = new Intent(this, DisplayMessageActivity2.class);
            EditText editText = (EditText) findViewById(R.id.edit_message);
            String message = editText.getText().toString();
            intent.putExtra(EXTRA_MESSAGE, message);
            startActivity(intent);


        }

    }

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);
    }
}

我的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activity_display_message.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activity_display_message2.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>

我的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>

你能在一个程序中两次开始另一项活动吗？

0 个答案: