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我正在按照教程创建一个应用程序来测量 GSM 信号强度。我的文件中没有错误。但我的应用程序不会在设备中运行。我附上了我的代码。有人能找出错误在哪里吗？

我的主要活动代码

package com.example.getgsmsignalstrength;

import android.os.Bundle;
import android.app.Activity;
import android.content.Context;
import android.telephony.PhoneStateListener;
import android.telephony.SignalStrength;
import android.telephony.TelephonyManager;
import android.widget.Toast;

 public class MainActivity extends Activity
 {
   TelephonyManager        Tel;
    MyPhoneStateListener    MyListener;
    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        /* Update the listener, and start it */
        MyListener   = new MyPhoneStateListener();
        Tel       = ( TelephonyManager 
 )getSystemService(Context.TELEPHONY_SERVICE);
      Tel.listen(MyListener ,PhoneStateListener.LISTEN_SIGNAL_STRENGTHS);
    }

    /* Called when the application is minimized */
    @Override
   protected void onPause()
    {
      super.onPause();
      Tel.listen(MyListener, PhoneStateListener.LISTEN_NONE);
   }

    /* Called when the application resumes */
   @Override
   protected void onResume()
   {
      super.onResume();
      Tel.listen(MyListener,PhoneStateListener.LISTEN_SIGNAL_STRENGTHS);
   }

   /* —————————– */
    /* Start the PhoneState listener */
   /* —————————– */
    private class MyPhoneStateListener extends PhoneStateListener
    {
      @Override
      public void onSignalStrengthsChanged(SignalStrength signalStrength)
      {
         super.onSignalStrengthsChanged(signalStrength);
         Toast.makeText(getApplicationContext(), "Go to Firstdroid!!! GSM Cinr = "
            + String.valueOf(signalStrength.getGsmSignalStrength()), 
Toast.LENGTH_SHORT).show();
      }

    };/* End of private Class */

}/* GetGsmSignalStrength */

我的清单文件

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.getgsmsignalstrength"
android:versionCode="1"
android:versionName="1.0" >

<uses-sdk
    android:minSdkVersion="8"></uses-sdk>
<uses-permission
    android:name="android.permission.CHANGE_NETWORK_STATE">

</uses-permission>

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

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

我的主要：

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


</LinearLayout>

我的 logcat 显示：

06-19 12:04:20.843: D/AndroidRuntime(24717): Shutting down VM
06-19 12:04:20.843: W/dalvikvm(24717): threadid=1: thread exiting with uncaught 

exception (group=0x40018578)
06-19 12:04:20.843: E/AndroidRuntime(24717): FATAL EXCEPTION: main
06-19 12:04:20.843: E/AndroidRuntime(24717): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.getgsmsignalstrength/com.example.getgsmsignalstrength.getgsmsignalstrength}: java.lang.ClassNotFoundException: com.example.getgsmsignalstrength.getgsmsignalstrength in loader dalvik.system.PathClassLoader[/data/app/com.example.getgsmsignalstrength-2.apk]
06-19 12:04:20.843: E/AndroidRuntime(24717):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1573)
06-19 12:04:20.843: E/AndroidRuntime(24717):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1667)
06-19 12:04:20.843: E/AndroidRuntime(24717):    at android.app.ActivityThread.access$1500(ActivityThread.java:117)
06-19 12:04:20.843: E/AndroidRuntime(24717):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:935)
06-19 12:04:20.843: E/AndroidRuntime(24717):    at android.os.Handler.dispatchMessage(Handler.java:99)
06-19 12:04:20.843: E/AndroidRuntime(24717):    at android.os.Looper.loop(Looper.java:130)
06-19 12:04:20.843: E/AndroidRuntime(24717):    at android.app.ActivityThread.main(ActivityThread.java:3687)
06-19 12:04:20.843: E/AndroidRuntime(24717):    at java.lang.reflect.Method.invokeNative(Native Method)
06-19 12:04:20.843: E/AndroidRuntime(24717):    at java.lang.reflect.Method.invoke(Method.java:507)
06-19 12:04:20.843: E/AndroidRuntime(24717):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867)
06-19 12:04:20.843: E/AndroidRuntime(24717):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:625)
06-19 12:04:20.843: E/AndroidRuntime(24717):    at dalvik.system.NativeStart.main(Native Method)
06-19 12:04:20.843: E/AndroidRuntime(24717): Caused by: java.lang.ClassNotFoundException: com.example.getgsmsignalstrength.getgsmsignalstrength in loader dalvik.system.PathClassLoader[/data/app/com.example.getgsmsignalstrength-2.apk]
06-19 12:04:20.843: E/AndroidRuntime(24717):    at dalvik.system.PathClassLoader.findClass(PathClassLoader.java:240)
06-19 12:04:20.843: E/AndroidRuntime(24717):    at java.lang.ClassLoader.loadClass(ClassLoader.java:551)
06-19 12:04:20.843: E/AndroidRuntime(24717):    at java.lang.ClassLoader.loadClass(ClassLoader.java:511)
06-19 12:04:20.843: E/AndroidRuntime(24717):    at android.app.Instrumentation.newActivity(Instrumentation.java:1021)
06-19 12:04:20.843: E/AndroidRuntime(24717):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1565)
06-19 12:04:20.843: E/AndroidRuntime(24717):    ... 11 more
4

3 回答 3

0

您收到此错误是因为getgsmsignalstrength在您的项目中没有定义名称的活动。在您的清单中将活动名称标签更改为

<activity
        android:name=".MainActivity"
        android:label="@string/app_name" >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
</activity>
于 2014-06-19T06:44:44.163 回答
0

你得到类未找到异常。

根据您在问题中提供的内容，您没有在清单文件中写入正确的活动名称。您的活动名称是MainActivity，并且您已经编写了 getgsmsignalstrength。请进行如下所示的修改。

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.getgsmsignalstrength"

...

<application

...

<activity
    <!--android:name=".getgsmsignalstrength"-->
    android:name=".MainActivity"
    android:label="@string/app_name" >
    <intent-filter>
        <action android:name="android.intent.action.MAIN" />

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

于 2014-06-19T06:47:53.633 回答
0 
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.getgsmsignalstrength"
android:versionCode="1"
android:versionName="1.0" >

<uses-sdk
    android:minSdkVersion="8"></uses-sdk>
<uses-permission
    android:name="android.permission.CHANGE_NETWORK_STATE">

</uses-permission>

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

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

在 manifest.xml 中更改您的活动名称。您的活动名称是MainActivity，而不是您在 tour manifest.xml文件中定义的名称。

于 2014-06-19T06:45:41.163 回答