我是 Android 新手，而且不太擅长。所以请耐心听我说，请非常清楚和基本地回答您的问题。
我正在尝试在 android 中制作一个导航微调器。我使用教程制作了它，但我不知道如何修改他们引导用户访问的页面。现在，我试图让它们全部进入同一个页面，其中只有一个基本的“Hello”。但该应用程序不断崩溃。
public class MainActivity extends ActionBarActivity implements
ActionBar.OnNavigationListener {
/**
* The serialization (saved instance state) Bundle key representing the
* current dropdown position.
*/
private static final String STATE_SELECTED_NAVIGATION_ITEM = "selected_navigation_item";
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Set up the action bar to show a dropdown list.
final ActionBar actionBar = getSupportActionBar();
actionBar.setDisplayShowTitleEnabled(false);
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_LIST);
// Set up the dropdown list navigation in the action bar.
actionBar.setListNavigationCallbacks(
// Specify a SpinnerAdapter to populate the dropdown list.
new ArrayAdapter<String>(actionBar.getThemedContext(),
android.R.layout.simple_list_item_1,
android.R.id.text1, new String[] {
getString(R.string.title_section1),
getString(R.string.title_section2),
getString(R.string.title_section3), }), this);
}
public void onRestoreInstanceState(Bundle savedInstanceState) {
// Restore the previously serialized current dropdown position.
if (savedInstanceState.containsKey(STATE_SELECTED_NAVIGATION_ITEM)) {
getSupportActionBar().setSelectedNavigationItem(
savedInstanceState.getInt(STATE_SELECTED_NAVIGATION_ITEM));
}
}
public void onSaveInstanceState(Bundle outState) {
// Serialize the current dropdown position.
outState.putInt(STATE_SELECTED_NAVIGATION_ITEM, getSupportActionBar()
.getSelectedNavigationIndex());
}
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
public boolean onNavigationItemSelected(int position, long id) {
// When the given dropdown item is selected, show its contents in the
// container view.
Intent intent = new Intent (this, Fibonacci.class);
startActivity(intent);
return true;
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
/**
* The fragment argument representing the section number for this
* fragment.
*/
private static final String ARG_SECTION_NUMBER = "section_number";
/**
* Returns a new instance of this fragment for the given section number.
*/
public static PlaceholderFragment newInstance(int sectionNumber) {
PlaceholderFragment fragment = new PlaceholderFragment();
Bundle args = new Bundle();
args.putInt(ARG_SECTION_NUMBER, sectionNumber);
fragment.setArguments(args);
return fragment;
}
public PlaceholderFragment() {
}
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container,
false);
TextView textView = (TextView) rootView
.findViewById(R.id.section_label);
textView.setText(Integer.toString(getArguments().getInt(
ARG_SECTION_NUMBER)));
return rootView;
}
}
}
还有:
public class Fibonacci extends Activity {
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Get the message from the intent
Intent intent = getIntent();
String message = "Hello";
// Create the text view
TextView textView = new TextView(this);
textView.setTextSize(40);
textView.setText(message);
// Set the text view as the activity layout
setContentView(textView);
}
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
/**
* The fragment argument representing the section number for this
* fragment.
*/
private static final String ARG_SECTION_NUMBER = "section_number";
/**
* Returns a new instance of this fragment for the given section number.
*/
public static PlaceholderFragment newInstance(int sectionNumber) {
PlaceholderFragment fragment = new PlaceholderFragment();
Bundle args = new Bundle();
args.putInt(ARG_SECTION_NUMBER, sectionNumber);
fragment.setArguments(args);
return fragment;
}
public PlaceholderFragment() {
}
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container,
false);
TextView textView = (TextView) rootView
.findViewById(R.id.section_label);
textView.setText(Integer.toString(getArguments().getInt(
ARG_SECTION_NUMBER)));
return rootView;
}
}
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
public static int fibonacciNum (int position) {
int num = 1;
if (position <= 2) {
return 1;
}
else {
num = fibonacciNum(position-1) + fibonacciNum(position-2);
return num;
}
}
}
日志猫:
07-15 10:08:13.850: E/AndroidRuntime(921): FATAL EXCEPTION: main
07-15 10:08:13.850: E/AndroidRuntime(921): Process: com.zarwanhashem.sequences, PID: 921
07-15 10:08:13.850: E/AndroidRuntime(921): android.content.ActivityNotFoundException: Unable to find explicit activity class {com.zarwanhashem.sequences/com.zarwanhashem.sequences.Fibonacci}; have you declared this activity in your AndroidManifest.xml?
07-15 10:08:13.850: E/AndroidRuntime(921): at android.app.Instrumentation.checkStartActivityResult(Instrumentation.java:1628)
07-15 10:08:13.850: E/AndroidRuntime(921): at android.app.Instrumentation.execStartActivity(Instrumentation.java:1424)
07-15 10:08:13.850: E/AndroidRuntime(921): at android.app.Activity.startActivityForResult(Activity.java:3424)
07-15 10:08:13.850: E/AndroidRuntime(921): at android.app.Activity.startActivityForResult(Activity.java:3385)
07-15 10:08:13.850: E/AndroidRuntime(921): at android.support.v4.app.FragmentActivity.startActivityForResult(FragmentActivity.java:839)
07-15 10:08:13.850: E/AndroidRuntime(921): at android.app.Activity.startActivity(Activity.java:3627)
07-15 10:08:13.850: E/AndroidRuntime(921): at android.app.Activity.startActivity(Activity.java:3595)
07-15 10:08:13.850: E/AndroidRuntime(921): at com.zarwanhashem.sequences.MainActivity.onNavigationItemSelected(MainActivity.java:91)
07-15 10:08:13.850: E/AndroidRuntime(921): at android.support.v7.app.ActionBarImplICS$OnNavigationListenerWrapper.onNavigationItemSelected(ActionBarImplICS.java:355)
07-15 10:08:13.850: E/AndroidRuntime(921): at com.android.internal.widget.ActionBarView$1.onItemSelected(ActionBarView.java:145)
07-15 10:08:13.850: E/AndroidRuntime(921): at android.widget.AdapterView.fireOnSelected(AdapterView.java:893)
07-15 10:08:13.850: E/AndroidRuntime(921): at android.widget.AdapterView.access$200(AdapterView.java:48)
07-15 10:08:13.850: E/AndroidRuntime(921): at android.widget.AdapterView$SelectionNotifier.run(AdapterView.java:861)
07-15 10:08:13.850: E/AndroidRuntime(921): at android.os.Handler.handleCallback(Handler.java:733)
07-15 10:08:13.850: E/AndroidRuntime(921): at android.os.Handler.dispatchMessage(Handler.java:95)
07-15 10:08:13.850: E/AndroidRuntime(921): at android.os.Looper.loop(Looper.java:136)
07-15 10:08:13.850: E/AndroidRuntime(921): at android.app.ActivityThread.main(ActivityThread.java:5017)
07-15 10:08:13.850: E/AndroidRuntime(921): at java.lang.reflect.Method.invokeNative(Native Method)
07-15 10:08:13.850: E/AndroidRuntime(921): at java.lang.reflect.Method.invoke(Method.java:515)
07-15 10:08:13.850: E/AndroidRuntime(921): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
07-15 10:08:13.850: E/AndroidRuntime(921): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
07-15 10:08:13.850: E/AndroidRuntime(921): at dalvik.system.NativeStart.main(Native Method)
list :
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="19" />
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name="com.zarwanhashem.sequences.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>
最佳答案
android.content.ActivityNotFoundException: Unable to find explicit activity class {com.zarwanhashem.sequences/com.zarwanhashem.sequences.Fibonacci}; have you declared this activity in your AndroidManifest.xml?
您打算在应用程序中调用的每个 Activity 都必须在 AndroidManifest 文件中声明。最少需要的是:
<activity android:name=".Fibonacci" />
关于java - 如何使用 Android 导航微调器，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/24728541/