Question

我正在尝试制作一个简单的应用来测试Services类。我想要一个按钮，按下按钮启动服务并显示服务已启动的Toast，但是，每当我按下按钮时，应用程序崩溃，我不知道问题是什么。测试类：

public class ControllerTestingScreen extends Activity{

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_controller_test_screen);
    //Set button colors to red, green, blue, and red, respectively
    Button button = (Button) findViewById(R.id.testbutton);
    button.getBackground().setColorFilter(0xFFFF0000, PorterDuff.Mode.MULTIPLY);
    OnClickListener buttonListener = new View.OnClickListener(){
        public void onClick(View arg0) {

            startService(new Intent(getBaseContext(),Controller.class));
            //sendSMS("PutPhoneNumberHereForTesting","WhereYouApp Text Message Test");
        }
    };
    button.setOnClickListener(buttonListener);
}

清单文件

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

<uses-sdk
    android:minSdkVersion="8"
    android:targetSdkVersion="19" />
<activity

         android:name="com.example.whereyouapp.ControllerTestingScreen"
         android:label="YOLO">

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

     </activity>

      <service android:name="com.example.whereyouapp.Controller"/>
      </application>
</manifest>

控制器类：

public class Controller extends Service{

private static final int POLL_INTERVAL = 1000 * 30;

public Controller(String name) {
    super();
    // TODO Auto-generated constructor stub
}
public int onStartCommand(Intent intent,int flags, int startId){
    Toast.makeText(this, "yololo- the service class works", Toast.LENGTH_LONG).show();

    return START_STICKY;
}

public void onDestroy(){
    super.onDestroy();
    Toast.makeText(this, "yolo- the service has stopped working", Toast.LENGTH_LONG).show();


}

}

我收到的错误：

logcat error: 02-23 14:10:40.187: E/AndroidRuntime(1173): java.lang.RuntimeException: Unable to instantiate service com.example.whereyouapp.Controller: java.lang.InstantiationException: can't instantiate class com.example.whereyouapp.Controller; no empty constructor

Answer 1

如果您定义：

，您的服务确实需要无参数构造函数

public Controller(String name)

然后java不会自动添加参数少一个，并且android需要它使用startService来实例化你的服务

Answer 2

我无法在您的清单O_o

中看到<application>张开标记

服务无法运行-Android应用程序崩溃

2 个答案: