我得到了一个nullptr,我读了一些帖子,但我似乎无法追捕这个,我是应用程序开发的新手;任何帮助将不胜感激。错误发生在这里:
adapter = new ArrayAdapter<String>(getApplicationContext(), android.R.layout.simple_spinner_item, arrayList);
list.setAdapter(adapter);
以下是主要活动:
public class MainActivity extends ActionBarActivity {
public final static String EXTRA_MESSAGE = "com.example.ciltkick.nom.MainActivity";
private EditText editTxt;
private Button btn;
private ListView list;
private ArrayAdapter<String> adapter;
private ArrayList<String> arrayList;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment())
.commit();
}
editTxt = (EditText) findViewById(R.id.msg);
btn = (Button) findViewById(R.id.addNom);
list = (ListView) findViewById(R.id.list_item);
arrayList = new ArrayList<String>();
adapter = new ArrayAdapter<String>(getApplicationContext(), android.R.layout.simple_spinner_item, arrayList);
list.setAdapter(adapter);
btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
}
});
}
这是xml:
<TableLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:baselineAligned="false">
<TableRow
android:layout_width="wrap_content"
android:layout_height="wrap_content">
<EditText android:id="@+id/msg"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:hint="@string/msg"
android:layout_weight="1"/>
<Button
android:id="@+id/addNom"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/button_send"
android:onClick="addNom"/>
</TableRow>
<TableRow
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_weight="1"
android:layout_gravity="center_vertical">
<ListView android:id="@+id/list_item"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</TableRow>
</TableLayout>
这是清单:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.ciltkick.nom" >
<uses-sdk android:minSdkVersion="11"></uses-sdk>
<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>
<activity
android:name=".SecondaryActivity"
android:label="@string/title_activity_secondary"
android:parentActivityName=".MainActivity">
<meta-data
android:name="android.support.PARENT_ACTIVITY"
android:value="com.example.ciltkick.nom.MainActivity" />
</activity>
</application>
</manifest>
这是stacktrace:
01-07 17:52:04.494 26339-26339/com.example.ciltkick.nom E/Trace﹕ error opening trace file: No such file or directory (2)
01-07 17:52:06.455 26339-26339/com.example.ciltkick.nom E/AndroidRuntime﹕ FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.ciltkick.nom/com.example.ciltkick.nom.MainActivity}: java.lang.ClassNotFoundException: com.example.ciltkick.nom.MainActivity
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1995)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2096)
at android.app.ActivityThread.access$600(ActivityThread.java:138)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1207)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:213)
at android.app.ActivityThread.main(ActivityThread.java:4787)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:789)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:556)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.ClassNotFoundException: com.example.ciltkick.nom.MainActivity
at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:61)
at java.lang.ClassLoader.loadClass(ClassLoader.java:501)
at java.lang.ClassLoader.loadClass(ClassLoader.java:461)
at android.app.Instrumentation.newActivity(Instrumentation.java:1053)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1986)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2096)
at android.app.ActivityThread.access$600(ActivityThread.java:138)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1207)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:213)
at android.app.ActivityThread.main(ActivityThread.java:4787)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:789)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:556)
at dalvik.system.NativeStart.main(Native Method)