android - "Unable to instantiate activity ComponentInfo"

Question

我是所有这些 android 开发的新手，我正试图找出这个异常的原因。

    11-09 02:29:39.897: E/AndroidRuntime(657): FATAL EXCEPTION: main
11-09 02:29:39.897: E/AndroidRuntime(657): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.yoursite.arduinoblinkled/com.yoursite.arduinoblinkled.activity_arduino_blink_led}: java.lang.ClassNotFoundException: com.yoursite.arduinoblinkled.activity_arduino_blink_led
11-09 02:29:39.897: E/AndroidRuntime(657):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1880)
11-09 02:29:39.897: E/AndroidRuntime(657):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981)
11-09 02:29:39.897: E/AndroidRuntime(657):  at android.app.ActivityThread.access$600(ActivityThread.java:123)
11-09 02:29:39.897: E/AndroidRuntime(657):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147)
11-09 02:29:39.897: E/AndroidRuntime(657):  at android.os.Handler.dispatchMessage(Handler.java:99)
11-09 02:29:39.897: E/AndroidRuntime(657):  at android.os.Looper.loop(Looper.java:137)
11-09 02:29:39.897: E/AndroidRuntime(657):  at android.app.ActivityThread.main(ActivityThread.java:4424)
11-09 02:29:39.897: E/AndroidRuntime(657):  at java.lang.reflect.Method.invokeNative(Native Method)
11-09 02:29:39.897: E/AndroidRuntime(657):  at java.lang.reflect.Method.invoke(Method.java:511)
11-09 02:29:39.897: E/AndroidRuntime(657):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
11-09 02:29:39.897: E/AndroidRuntime(657):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
11-09 02:29:39.897: E/AndroidRuntime(657):  at dalvik.system.NativeStart.main(Native Method)
11-09 02:29:39.897: E/AndroidRuntime(657): Caused by: java.lang.ClassNotFoundException: com.yoursite.arduinoblinkled.activity_arduino_blink_led
11-09 02:29:39.897: E/AndroidRuntime(657):  at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:61)
11-09 02:29:39.897: E/AndroidRuntime(657):  at java.lang.ClassLoader.loadClass(ClassLoader.java:501)
11-09 02:29:39.897: E/AndroidRuntime(657):  at java.lang.ClassLoader.loadClass(ClassLoader.java:461)
11-09 02:29:39.897: E/AndroidRuntime(657):  at android.app.Instrumentation.newActivity(Instrumentation.java:1023)
11-09 02:29:39.897: E/AndroidRuntime(657):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1871)
11-09 02:29:39.897: E/AndroidRuntime(657):  ... 11 more

AndroidManifest.xml

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

     <uses-sdk
        android:minSdkVersion="15"
        android:targetSdkVersion="15" />

    <application android:icon="@drawable/ic_launcher" android:label="@string/app_name">
        <uses-library android:name="com.google.android.maps" />
        <activity android:name=".activity_arduino_blink_led"
            android:label="@string/app_name">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
            <intent-filter>
                <action android:name="android.hardware.usb.action.USB_ACCESSORY_ATTACHED" />
            </intent-filter>
            <meta-data android:name="android.hardware.usb.action.USB_ACCESSORY_ATTACHED"
                android:resource="@xml/device_filter" />
        </activity>

        <uses-library android:name="com.android.future.usb.accessory"></uses-library>

    </application>
</manifest>

ArduinoBlinkLEDActivity.java

package com.example.arduinoblinkled;

import java.io.FileDescriptor;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;


import com.android.future.usb.UsbAccessory;
import com.android.future.usb.UsbManager;
import com.yoursite.arduinoblinkled.R;


import android.os.Bundle;
import android.os.ParcelFileDescriptor;
import android.app.Activity;
import android.app.PendingIntent;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.widget.ToggleButton;

public class ArduinoBlinkLEDActivity extends Activity {




        private static final String TAG = "ArduinoAccessory";

        private static final String ACTION_USB_PERMISSION = "com.google.android.DemoKit.action.USB_PERMISSION";

        private UsbManager mUsbManager;
        private PendingIntent mPermissionIntent;
        private boolean mPermissionRequestPending;
        private ToggleButton buttonLED;

        UsbAccessory mAccessory;
        ParcelFileDescriptor mFileDescriptor;
        FileInputStream mInputStream;
        FileOutputStream mOutputStream;

        private final BroadcastReceiver mUsbReceiver = new BroadcastReceiver() {
            @Override
            public void onReceive(Context context, Intent intent) {
                String action = intent.getAction();
                if (ACTION_USB_PERMISSION.equals(action)) {
                    synchronized (this) {
                        UsbAccessory accessory = UsbManager.getAccessory(intent);
                        if (intent.getBooleanExtra(
                                UsbManager.EXTRA_PERMISSION_GRANTED, false)) {
                            openAccessory(accessory);
                        } else {
                            Log.d(TAG, "permission denied for accessory "
                                    + accessory);
                        }
                        mPermissionRequestPending = false;
                    }
                } else if (UsbManager.ACTION_USB_ACCESSORY_DETACHED.equals(action)) {
                    UsbAccessory accessory = UsbManager.getAccessory(intent);
                    if (accessory != null && accessory.equals(mAccessory)) {
                        closeAccessory();
                    }
                }
            }
        };


    @SuppressWarnings("deprecation")
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_arduino_blink_led);

        mUsbManager = UsbManager.getInstance(this);
        mPermissionIntent = PendingIntent.getBroadcast(this, 0, new Intent(ACTION_USB_PERMISSION), 0);
        IntentFilter filter = new IntentFilter(ACTION_USB_PERMISSION);
        filter.addAction(UsbManager.ACTION_USB_ACCESSORY_DETACHED);
        registerReceiver(mUsbReceiver, filter);

        if (getLastNonConfigurationInstance() != null) {
            mAccessory = (UsbAccessory) getLastNonConfigurationInstance();
            openAccessory(mAccessory);
        }

        setContentView(R.layout.activity_arduino_blink_led);
        buttonLED = (ToggleButton) findViewById(R.id.toggleButtonLED);
    }

    @SuppressWarnings("deprecation")
    @Override
    public Object onRetainNonConfigurationInstance() {
        if (mAccessory != null) {
            return mAccessory;
        } else {
            return super.onRetainNonConfigurationInstance();
        }
    }

    @Override
    public void onResume() {
        super.onResume();

        if (mInputStream != null && mOutputStream != null) {
            return;
        }

        UsbAccessory[] accessories = mUsbManager.getAccessoryList();
        UsbAccessory accessory = (accessories == null ? null : accessories[0]);
        if (accessory != null) {
            if (mUsbManager.hasPermission(accessory)) {
                openAccessory(accessory);
            } else {
                synchronized (mUsbReceiver) {
                    if (!mPermissionRequestPending) {
                        mUsbManager.requestPermission(accessory,mPermissionIntent);
                        mPermissionRequestPending = true;
                    }
                }
            }
        } else {
            Log.d(TAG, "mAccessory is null");
        }
    }

    private void openAccessory(UsbAccessory accessory) {
        mFileDescriptor = mUsbManager.openAccessory(accessory);
        if (mFileDescriptor != null) {
            mAccessory = accessory;
            FileDescriptor fd = mFileDescriptor.getFileDescriptor();
            mInputStream = new FileInputStream(fd);
            mOutputStream = new FileOutputStream(fd);
            Log.d(TAG, "accessory opened");
        } else {
            Log.d(TAG, "accessory open fail");
        }
    }


    private void closeAccessory() {
        try {
            if (mFileDescriptor != null) {
                mFileDescriptor.close();
            }
        } catch (IOException e) {
        } finally {
            mFileDescriptor = null;
            mAccessory = null;
        }
    }

    public void blinkLED(View v){

        byte[] buffer = new byte[1];

        if(buttonLED.isChecked())
            buffer[0]=(byte)0; // button says on, light is off
        else
            buffer[0]=(byte)1; // button says off, light is on

        if (mOutputStream != null) {
            try {
                mOutputStream.write(buffer);
            } catch (IOException e) {
                Log.e(TAG, "write failed", e);
            }
        }
    }


}

我尝试了很多解决方案，但问题仍然没有解决。有谁知道这可能是什么原因造成的？非常感谢。

Answer 1

因为，您没有为 Activity 使用完全限定名称，请将顶部的包名称更改为 com.example.arduinoblinkled。

同时将 Activity 名称更改为 .ArduinoBlinkLEDActivity