我的应用在首次运行时运行良好。在菜单上我添加了两个选项并退出。 设置新意图的选项转到PreferenceActivity并退出，只需调用： “android.os.Process.killProcess（android.os.Process.myPid（））;”
第二次运行我的应用程序（在我从模拟器内部退出后）它崩溃了.. 想法？ 该菜单由以下代码调用：
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.menu , menu);
return true;
}
-
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Set up a new intent between the updater service and the main screen
Intent options = new Intent(this, OptionsScreenActivity.class);
// Switch case on the options
switch (item.getItemId()) {
case R.id.options:
startActivity(options);
return true;
case R.id.quit:
android.os.Process.killProcess(android.os.Process.myPid());
return true;
default:
return false;
}
SeekBarPreference的代码：
package com.testapp.logic;
import com.testapp.R;
import android.content.Context;
import android.content.res.TypedArray;
import android.preference.Preference;
import android.util.AttributeSet;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewParent;
import android.widget.RelativeLayout;
import android.widget.SeekBar;
import android.widget.SeekBar.OnSeekBarChangeListener;
import android.widget.TextView;
public class SeekBarPreference extends Preference implements OnSeekBarChangeListener {
private final String TAG = getClass().getName();
private static final String ANDROIDNS="http://schemas.android.com/apk/res/android";
private static final String PREFS="com.testapp.logic";
private static final int DEFAULT_VALUE = 5;
private int mMaxValue = 100;
private int mMinValue = 1;
private int mInterval = 1;
private int mCurrentValue;
private String mUnitsLeft = "";
private String mUnitsRight = "";
private SeekBar mSeekBar;
private TextView mStatusText;
public SeekBarPreference(Context context, AttributeSet attrs) {
super(context, attrs);
initPreference(context, attrs);
}
public SeekBarPreference(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
initPreference(context, attrs);
}
private void initPreference(Context context, AttributeSet attrs) {
setValuesFromXml(attrs);
mSeekBar = new SeekBar(context, attrs);
mSeekBar.setMax(mMaxValue - mMinValue);
mSeekBar.setOnSeekBarChangeListener(this);
}
private void setValuesFromXml(AttributeSet attrs) {
mMaxValue = attrs.getAttributeIntValue(ANDROIDNS, "max", 100);
mMinValue = attrs.getAttributeIntValue(PREFS, "min", 0);
mUnitsLeft = getAttributeStringValue(attrs, PREFS, "unitsLeft", "");
String units = getAttributeStringValue(attrs, PREFS, "units", "");
mUnitsRight = getAttributeStringValue(attrs, PREFS, "unitsRight", units);
try {
String newInterval = attrs.getAttributeValue(PREFS, "interval");
if(newInterval != null)
mInterval = Integer.parseInt(newInterval);
}
catch(Exception e) {
Log.e(TAG, "Invalid interval value", e);
}
}
private String getAttributeStringValue(AttributeSet attrs, String namespace, String name, String defaultValue) {
String value = attrs.getAttributeValue(namespace, name);
if(value == null)
value = defaultValue;
return value;
}
@Override
protected View onCreateView(ViewGroup parent){
RelativeLayout layout = null;
try {
LayoutInflater mInflater = (LayoutInflater) getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
layout = (RelativeLayout)mInflater.inflate(R.layout.seek_bar_preference, parent, false);
}
catch(Exception e)
{
Log.e(TAG, "Error creating seek bar preference", e);
}
return layout;
}
@Override
public void onBindView(View view) {
super.onBindView(view);
try
{
// move our seekbar to the new view we've been given
ViewParent oldContainer = mSeekBar.getParent();
ViewGroup newContainer = (ViewGroup) view.findViewById(R.id.seekBarPrefBarContainer);
if (oldContainer != newContainer) {
// remove the seekbar from the old view
if (oldContainer != null) {
((ViewGroup) oldContainer).removeView(mSeekBar);
}
// remove the existing seekbar (there may not be one) and add ours
newContainer.removeAllViews();
newContainer.addView(mSeekBar, ViewGroup.LayoutParams.FILL_PARENT,
ViewGroup.LayoutParams.WRAP_CONTENT);
}
}
catch(Exception ex) {
Log.e(TAG, "Error binding view: " + ex.toString());
}
updateView(view);
}
/**
* Update a SeekBarPreference view with our current state
* @param view
*/
protected void updateView(View view) {
try {
RelativeLayout layout = (RelativeLayout)view;
mStatusText = (TextView)layout.findViewById(R.id.seekBarPrefValue);
mStatusText.setText(String.valueOf(mCurrentValue));
mStatusText.setMinimumWidth(30);
mSeekBar.setProgress(mCurrentValue - mMinValue);
TextView unitsRight = (TextView)layout.findViewById(R.id.seekBarPrefUnitsRight);
unitsRight.setText(mUnitsRight);
TextView unitsLeft = (TextView)layout.findViewById(R.id.seekBarPrefUnitsLeft);
unitsLeft.setText(mUnitsLeft);
}
catch(Exception e) {
Log.e(TAG, "Error updating seek bar preference", e);
}
}
public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
int newValue = progress + mMinValue;
if(newValue > mMaxValue)
newValue = mMaxValue;
else if(newValue < mMinValue)
newValue = mMinValue;
else if(mInterval != 1 && newValue % mInterval != 0)
newValue = Math.round(((float)newValue)/mInterval)*mInterval;
// change rejected, revert to the previous value
if(!callChangeListener(newValue)){
seekBar.setProgress(mCurrentValue - mMinValue);
return;
}
// change accepted, store it
mCurrentValue = newValue;
mStatusText.setText(String.valueOf(newValue));
persistInt(newValue);
}
public void onStartTrackingTouch(SeekBar seekBar) {}
public void onStopTrackingTouch(SeekBar seekBar) {
notifyChanged();
}
@Override
protected Object onGetDefaultValue(TypedArray ta, int index){
int defaultValue = ta.getInt(index, DEFAULT_VALUE);
return defaultValue;
}
@Override
protected void onSetInitialValue(boolean restoreValue, Object defaultValue) {
if(restoreValue) {
mCurrentValue = getPersistedInt(mCurrentValue);
}
else {
int temp = 0;
try {
temp = (Integer)defaultValue;
}
catch(Exception ex) {
Log.e(TAG, "Invalid default value: " + defaultValue.toString());
}
persistInt(temp);
mCurrentValue = temp;
}
}
}
logcat的：
E/AndroidRuntime( 4525): FATAL EXCEPTION: main
E/AndroidRuntime( 4525): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.ui.testapp/com.logic.testapp.SeekBarPreferen
ce}: java.lang.InstantiationException: can't instantiate class com.logic.testapp.SeekBarPreference; no empty constructor
E/AndroidRuntime( 4525): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1879)
E/AndroidRuntime( 4525): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1980)
E/AndroidRuntime( 4525): at android.app.ActivityThread.access$600(ActivityThread.java:122)
E/AndroidRuntime( 4525): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1146)
E/AndroidRuntime( 4525): at android.os.Handler.dispatchMessage(Handler.java:99)
E/AndroidRuntime( 4525): at android.os.Looper.loop(Looper.java:137)
E/AndroidRuntime( 4525): at android.app.ActivityThread.main(ActivityThread.java:4340)
E/AndroidRuntime( 4525): at java.lang.reflect.Method.invokeNative(Native Method)
E/AndroidRuntime( 4525): at java.lang.reflect.Method.invoke(Method.java:511)
E/AndroidRuntime( 4525): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
E/AndroidRuntime( 4525): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
E/AndroidRuntime( 4525): at dalvik.system.NativeStart.main(Native Method)
E/AndroidRuntime( 4525): Caused by: java.lang.InstantiationException: can't instantiate class com.logic.testapp.SeekBarPreference; no empty construc
tor
E/AndroidRuntime( 4525): at java.lang.Class.newInstanceImpl(Native Method)
E/AndroidRuntime( 4525): at java.lang.Class.newInstance(Class.java:1319)
E/AndroidRuntime( 4525): at android.app.Instrumentation.newActivity(Instrumentation.java:1023)
E/AndroidRuntime( 4525): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1870)
E/AndroidRuntime( 4525): ... 11 more
W/ActivityManager( 84): Force finishing activity com.ui.testapp/com.logic.testapp.SeekBarPreference
W/ActivityManager( 84): Force finishing activity com.ui.testapp/.MainScreen
I/WindowManager( 84): createSurface Window{41a90320 paused=false}: DRAW NOW PENDING
W/ActivityManager( 84): Activity pause timeout for ActivityRecord{4104a848 com.ui.testapp/com.logic.testapp.SeekBarPreference}
W/NetworkManagementSocketTagger( 84): setKernelCountSet(10021, 1) failed with errno -2
I/WindowManager( 84): createSurface Window{412bcc10 com.android.launcher/com.android.launcher2.Launcher paused=false}: DRAW NOW PENDING
W/NetworkManagementSocketTagger( 84): setKernelCountSet(10045, 0) failed with errno -2
I/Process ( 4525): Sending signal. PID: 4525 SIG: 9
I/ActivityManager( 84): Process com.ui.testapp (pid 4525) has died.
I/WindowManager( 84): WIN DEATH: Window{41a6c9c0 com.ui.testapp/com.ui.testapp.MainScreen paused=true}