Android的 - 应用程序保持与错误而崩溃 - 我认为这与preference片段做 [英] Android - App keeps crashing with error - I think it has to do with Preference Fragments
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问题描述
我不断收到具有与preferences做了一个错误，我知道它有代pciated $ P $，所以我看了这里寻求帮助的http://developer.android.com/reference/android/$p$pference/$p$pferenceFragment.html
I keep getting an error that has to do with the preferences and I know it has depreciated so I looked here for help http://developer.android.com/reference/android/preference/PreferenceFragment.html
和我也正是因为它说在底部...
and I did exactly as it says on the bottom part...
以下是错误：
12-04 00:39:37.553: E/AndroidRuntime(1164): FATAL EXCEPTION: main
12-04 00:39:37.553: E/AndroidRuntime(1164): Process: com.proteintracker, PID: 1164
12-04 00:39:37.553: E/AndroidRuntime(1164): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.proteintracker/com.proteintracker.MainPreferenceActivity}: java.lang.ClassCastException: com.proteintracker.MainPreferenceActivity cannot be cast to android.app.Activity
12-04 00:39:37.553: E/AndroidRuntime(1164): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2102)
12-04 00:39:37.553: E/AndroidRuntime(1164): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2226)
12-04 00:39:37.553: E/AndroidRuntime(1164): at android.app.ActivityThread.access$700(ActivityThread.java:135)
12-04 00:39:37.553: E/AndroidRuntime(1164): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1397)
12-04 00:39:37.553: E/AndroidRuntime(1164): at android.os.Handler.dispatchMessage(Handler.java:102)
12-04 00:39:37.553: E/AndroidRuntime(1164): at android.os.Looper.loop(Looper.java:137)
12-04 00:39:37.553: E/AndroidRuntime(1164): at android.app.ActivityThread.main(ActivityThread.java:4998)
12-04 00:39:37.553: E/AndroidRuntime(1164): at java.lang.reflect.Method.invokeNative(Native Method)
12-04 00:39:37.553: E/AndroidRuntime(1164): at java.lang.reflect.Method.invoke(Method.java:515)
12-04 00:39:37.553: E/AndroidRuntime(1164): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:777)
12-04 00:39:37.553: E/AndroidRuntime(1164): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:593)
12-04 00:39:37.553: E/AndroidRuntime(1164): at dalvik.system.NativeStart.main(Native Method)
12-04 00:39:37.553: E/AndroidRuntime(1164): Caused by: java.lang.ClassCastException: com.proteintracker.MainPreferenceActivity cannot be cast to android.app.Activity
12-04 00:39:37.553: E/AndroidRuntime(1164): at android.app.Instrumentation.newActivity(Instrumentation.java:1061)
12-04 00:39:37.553: E/AndroidRuntime(1164): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2093)
12-04 00:39:37.553: E/AndroidRuntime(1164): ... 11 more
下面是我的code为preference类
Here is my code for the Preference class
package com.proteintracker;
import android.app.Activity;
import android.os.Bundle;
public class MainPreferenceActivity extends Activity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Display the fragment as the main content.
getFragmentManager().beginTransaction()
.replace(android.R.id.content, new MainPreferenceFragment())
.commit();
}
}
下面是我的code为preference片段类：
Here is my code for the preference fragment class:
package com.proteintracker;
import android.os.Bundle;
import android.preference.PreferenceFragment;
public class MainPreferenceFragment extends PreferenceFragment {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Load the preferences from an XML resource
addPreferencesFromResource(R.xml.main_preferences);
}
}
下面是它在我的xml文件
Here is my xml file for it
<?xml version="1.0" encoding="utf-8"?>
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android" android:orderingFromXml="true">
<EditTextPreference
android:dialogMessage="Enter grams"
android:dialogTitle="Protein Grams"
android:key="gramsPerDay"
android:title="Grams per day" />
</PreferenceScreen>
和这里是清单文件：
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.proteintracker"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="11"
android:targetSdkVersion="18" />
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
>
<activity android:name="MainActivity"><intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter></activity><activity
android:name="MainPreferenceActivity"
android:label="@string/app_name" >
</activity>
<activity android:name="HelpActivity"></activity>
</application>
</manifest>
编辑---
下面是我的主要活动文件：
Here is my main activity file:
package com.proteintracker;
import android.app.Activity;
import android.content.Intent;
import android.content.SharedPreferences;
import android.content.SharedPreferences.Editor;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class MainActivity extends Activity {
private OnClickListener buttonListener = new OnClickListener() {
@Override
public void onClick(View v) {
EditText editText = (EditText)findViewById(R.id.editText1);
Log.d("ProteinTracker", editText.getText().toString());
}
};
private OnClickListener helpButtonListener = new OnClickListener() {
@Override
public void onClick(View v) {
SharedPreferences preferences = getSharedPreferences("default", MODE_PRIVATE);
String value = preferences.getString("activityTest", "");
Log.d("ProteinTracker", value);
Intent intent = new Intent(MainActivity.this, MainPreferenceActivity.class);
startActivity(intent);
}
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if(savedInstanceState != null) {
Log.d("ProteinTracker", savedInstanceState.getString("keyName"));
}
TextView textView = (TextView) findViewById(R.id.mainActivityTextView);
textView.setText(R.string.test_updating_a_view);
Button button = (Button)findViewById(R.id.button1);
button.setOnClickListener(buttonListener );
Button helpButton = (Button)findViewById(R.id.helpButton);
helpButton.setOnClickListener(helpButtonListener );
SharedPreferences preferences = getSharedPreferences("default", MODE_PRIVATE);
Editor editor = preferences.edit();
editor.putString("activityTest", "activity value");
editor.commit();
}
@Override
protected void onSaveInstanceState(Bundle outState) {
outState.putString("keyName","string");
super.onSaveInstanceState(outState);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater menuInflater = getMenuInflater();
menuInflater.inflate(R.menu.main_menu, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch(item.getItemId()) {
case R.id.settingsMenuItem:
//launch settings activity
default:
}
return super.onOptionsItemSelected(item);
}
}
我更新了片段文件，并添加了一个新太也，包括我的主要活动文件。
I updated the fragment file and added a new one too and also, have included my main activity file.
我不知道我需要做的，我在Java和Android的新...谢谢！
I am not sure what I need to do, I am new at Java and Android... thanks!
推荐答案
片段需要被添加到活动。你应该改变你的主preferenceFragment片段从主要preferenceActivity的名字，所以你必须：
Fragments need to be added to activities. You should change the name of your fragment from MainPreferenceActivity to MainPreferenceFragment, so you'd have:
public class MainPreferenceFragment extends PreferenceFragment {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Load the preferences from an XML resource
addPreferencesFromResource(R.xml.main_preferences);
}
}
然后让主preferenceActivity延伸活动，在这里添加您的片段：
and then have MainPreferenceActivity extending Activity, where you add your fragment:
public class MainPreference Activity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Display the fragment as the main content.
getFragmentManager().beginTransaction()
.replace(android.R.id.content, new MainPreferenceFragment())
.commit();
}
}
这里更多。
Read more here.
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