我的Android应用程序总是崩溃

Question

我已经开始学习Android开发，我从google android开发网站上得到了这个片段，它一直在崩溃。

我的规格是：

Android 4.0.3 API 15

代码：

package lewes.android.hello;

import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;

public class HelloAndroid extends Activity {
   /** Called when the activity is first created. */
   @Override
   public void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       TextView tv = new TextView(this);
       tv.setText("Hello, Android");
       setContentView(tv);
   }
}

我得到..。

不巧的是，HelloAndroid没有响应。

请帮帮我!

我的清单：

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

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

<application
android:icon="@drawable/ic_launcher"
android:label="@string/app_name" >
<activity
android:name=".HelloWorld"
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>

LogCat：

03-17 11:35:19.835: D/AndroidRuntime(562): Shutting down VM
03-17 11:35:19.835: W/dalvikvm(562): threadid=1: thread exiting with uncaught 
exception (group=0x409c01f8) 
03-17 11:35:19.914: E/AndroidRuntime(562): FATAL EXCEPTION: main
03-17 11:35:19.914: E/AndroidRuntime(562): java.lang.RuntimeException: Unable to 
instantiate activity 
ComponentInfo{lewes.android.hello/lewes.android.hello.HelloWorld}: 
java.lang.ClassNotFoundException: lewes.android.hello.HelloWorld
03-17 11:35:19.914: E/AndroidRuntime(562):  at 
android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1880)
03-17 11:35:19.914: E/AndroidRuntime(562):  at 
android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981)
03-17 11:35:19.914: E/AndroidRuntime(562):  at 
android.app.ActivityThread.access$600(ActivityThread.java:123)
03-17 11:35:19.914: E/AndroidRuntime(562):  at  
android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147)
03-17 11:35:19.914: E/AndroidRuntime(562):  at 
android.os.Handler.dispatchMessage(Handler.java:99)
03-17 11:35:19.914: E/AndroidRuntime(562):  at android.os.Looper.loop(Looper.java:137)
03-17 11:35:19.914: E/AndroidRuntime(562):  at 
android.app.ActivityThread.main(ActivityThread.java:4424)
03-17 11:35:19.914: E/AndroidRuntime(562):  at 
java.lang.reflect.Method.invokeNative(Native Method)
03-17 11:35:19.914: E/AndroidRuntime(562):  at 
java.lang.reflect.Method.invoke(Method.java:511)
03-17 11:35:19.914: E/AndroidRuntime(562):  at 
com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
03-17 11:35:19.914: E/AndroidRuntime(562):  at 
com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
03-17 11:35:19.914: E/AndroidRuntime(562):  at dalvik.system.NativeStart.main(Native 
Method)
03-17 11:35:19.914: E/AndroidRuntime(562): Caused by: 
java.lang.ClassNotFoundException: lewes.android.hello.HelloWorld
03-17 11:35:19.914: E/AndroidRuntime(562):  at 
dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:61)
03-17 11:35:19.914: E/AndroidRuntime(562):  at 
java.lang.ClassLoader.loadClass(ClassLoader.java:501)
03-17 11:35:19.914: E/AndroidRuntime(562):  at  
java.lang.ClassLoader.loadClass(ClassLoader.java:461)
03-17 11:35:19.914: E/AndroidRuntime(562):  at 
android.app.Instrumentation.newActivity(Instrumentation.java:1023)
03-17 11:35:19.914: E/AndroidRuntime(562):  at  
android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1871)
03-17 11:35:19.914: E/AndroidRuntime(562):  ... 11 more
03-17 11:40:20.114: I/Process(562): Sending signal. PID: 562 SIG: 9

Answer 1

从清单中删除其中一个应用程序部分。保留活动与您的班级名称相对应的那个。

让你的清单看起来就像这样

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

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

<application
android:icon="@drawable/ic_launcher"
android:label="@string/app_name" >
<activity
android:name=".HelloAndroid"
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>

Answer 2

变化

 <activity
        android:name=".HelloAndroidActivity"

至

<activity
        android:name=".HelloAndroid"

Answer 3

SDK没有提到这一点。但根据我的经验，activity (this)不能在onCreate(Bundle)中用来初始化新对象。要用作构造函数的参数，在onCreate()中this是nothing。

您可以遵循此hello world。它使用静态xml布局。

希望这对你有帮助:-)