我现在一直在寻找一些描述Dalvik VM垃圾收集器架构的详细设计文档,但还没有变得太多.考虑到GC运行的性能影响,我真的希望更好地了解5个具体问题：
1.什么在 Android中触发GC？我看到的其他VM实现通常允许在GC接收到运行信号之前将一定百分比的系统内存分配给应用程序.扫描以下LogCat似乎显示Dalvik GC至少部分经常运行 –
1.什么在 Android中触发GC？我看到的其他VM实现通常允许在GC接收到运行信号之前将一定百分比的系统内存分配给应用程序.扫描以下LogCat似乎显示Dalvik GC至少部分经常运行 –
12-14 11:34:57.753: D/dalvikvm(279): GC_EXTERNAL_ALLOC freed 735 objects / 54272 bytes in 90ms 12-14 11:34:57.893: D/dalvikvm(279): GC_EXTERNAL_ALLOC freed 256 objects / 12240 bytes in 61ms 12-14 11:34:57.943: I/jPCT-AE(279): Loading Texture... 12-14 11:34:57.993: D/dalvikvm(279): GC_FOR_MALLOC freed 65 objects / 2840 bytes in 52ms 12-14 11:34:58.013: I/dalvikvm-heap(279): Grow heap (frag case) to 5.039MB for 1048592-byte allocation 12-14 11:34:58.073: D/dalvikvm(279): GC_FOR_MALLOC freed 1 objects / 40 bytes in 59ms 12-14 11:34:58.243: D/dalvikvm(279): GC_EXTERNAL_ALLOC freed 11 objects / 432 bytes in 55ms 12-14 11:34:58.283: I/jPCT-AE(279): Loading Texture... 12-14 11:34:58.333: D/dalvikvm(279): GC_FOR_MALLOC freed 10 objects / 416 bytes in 46ms 12-14 11:34:58.344: I/dalvikvm-heap(279): Grow heap (frag case) to 6.040MB for 1048592-byte allocation 12-14 11:34:58.423: D/dalvikvm(279): GC_FOR_MALLOC freed 2 objects / 80 bytes in 75ms 12-14 11:34:58.563: D/dalvikvm(279): GC_EXTERNAL_ALLOC freed 10 objects / 384 bytes in 47ms 12-14 11:34:58.603: I/jPCT-AE(279): Loading Texture... 12-14 11:34:58.653: D/dalvikvm(279): GC_FOR_MALLOC freed 11 objects / 464 bytes in 44ms 12-14 11:34:58.663: I/dalvikvm-heap(279): Grow heap (frag case) to 7.040MB for 1048592-byte allocation 12-14 11:34:58.743: D/dalvikvm(279): GC_FOR_MALLOC freed 2 objects / 80 bytes in 75ms 12-14 11:34:58.973: I/System.out(279): started document! ... 12-14 11:43:05.393: I/jPCT-AE(279): Memory usage before compacting: 5867 KB used out of 6215 KB 12-14 11:43:05.453: D/dalvikvm(279): GC_EXPLICIT freed 2560 objects / 145712 bytes in 61ms 12-14 11:43:05.503: D/dalvikvm(279): GC_EXPLICIT freed 295 objects / 21448 bytes in 51ms 12-14 11:43:05.717: I/jPCT-AE(279): Memory usage after compacting: 5705 KB used out of 6215 KB ... 12-14 11:43:05.792: D/dalvikvm(279): GC_EXTERNAL_ALLOC freed 105 objects / 6152 bytes in 56ms 12-14 11:43:05.855: D/dalvikvm(279): GC_FOR_MALLOC freed 3 objects / 80 bytes in 51ms ... 12-14 11:43:12.863: D/dalvikvm(279): GC_EXTERNAL_ALLOC freed 864 objects / 1099072 bytes in 70ms 12-14 11:43:13.053: D/dalvikvm(279): GC_EXTERNAL_ALLOC freed 45 objects / 1760 bytes in 55ms 12-14 11:43:14.533: D/dalvikvm(279): GC_EXTERNAL_ALLOC freed 49 objects / 2376 bytes in 58ms 12-14 11:43:14.933: D/dalvikvm(279): GC_EXTERNAL_ALLOC freed 34 objects / 1408 bytes in 55ms 12-14 11:43:15.423: D/dalvikvm(279): GC_EXTERNAL_ALLOC freed 13 objects / 504 bytes in 58ms 12-14 11:43:15.953: D/dalvikvm(279): GC_EXTERNAL_ALLOC freed 13 objects / 520 bytes in 56ms ... 12-14 11:43:31.203: I/jPCT-AE(279): Visibility lists disposed! 12-14 11:43:31.203: I/jPCT-AE(279): All texture data unloaded from gpu! 12-14 11:43:31.203: I/jPCT-AE(279): Renderer disposed! 12-14 11:43:31.203: I/jPCT-AE(279): Static references cleared... ... 12-14 11:43:36.943: E/dalvikvm-heap(279): 2964320-byte external allocation too large for this process. 12-14 11:43:36.953: E/GraphicsJNI(279): VM won't let us allocate 2964320 bytes 12-14 11:43:36.953: D/AndroidRuntime(279): Shutting down VM 12-14 11:43:36.953: W/dalvikvm(279): threadid=1: thread exiting with uncaught exception (group=0x4001d800) 12-14 11:43:36.973: E/AndroidRuntime(279): FATAL EXCEPTION: main 12-14 11:43:36.973: E/AndroidRuntime(279): android.view.InflateException: Binary XML file line #33: Error inflating class <unknown> 12-14 11:43:36.973: E/AndroidRuntime(279): at android.view.LayoutInflater.createView(LayoutInflater.java:513) 12-14 11:43:36.973: E/AndroidRuntime(279): at com.android.internal.policy.impl.PhoneLayoutInflater. onCreateView(PhoneLayoutInflater.java:56) 12-14 11:43:36.973: E/AndroidRuntime(279): at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:563) 12-14 11:43:36.973: E/AndroidRuntime(279): at android.view.LayoutInflater.rInflate(LayoutInflater.java:618) 12-14 11:43:36.973: E/AndroidRuntime(279): at android.view.LayoutInflater.rInflate(LayoutInflater.java:621) 12-14 11:43:36.973: E/AndroidRuntime(279): at android.view.LayoutInflater.inflate(LayoutInflater.java:407) 12-14 11:43:36.973: E/AndroidRuntime(279): at android.view.LayoutInflater.inflate(LayoutInflater.java:320) 12-14 11:43:36.973: E/AndroidRuntime(279): at com.ai.ultimap.views.Manual.onItemClick(Manual.java:467) 12-14 11:43:36.973: E/AndroidRuntime(279): at android.widget.AdapterView.performItemClick(AdapterView.java:284) 12-14 11:43:36.973: E/AndroidRuntime(279): at android.widget.AbsListView$PerformClick.run(AbsListView.java:1696) 12-14 11:43:36.973: E/AndroidRuntime(279): at android.os.Handler.handleCallback(Handler.java:587) 12-14 11:43:36.973: E/AndroidRuntime(279): at android.os.Handler.dispatchMessage(Handler.java:92) 12-14 11:43:36.973: E/AndroidRuntime(279): at android.os.Looper.loop(Looper.java:123) 12-14 11:43:36.973: E/AndroidRuntime(279): at android.app.ActivityThread.main(ActivityThread.java:4627) 12-14 11:43:36.973: E/AndroidRuntime(279): at java.lang.reflect.Method.invokeNative(Native Method) 12-14 11:43:36.973: E/AndroidRuntime(279): at java.lang.reflect.Method.invoke(Method.java:521) 12-14 11:43:36.973: E/AndroidRuntime(279): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868) 12-14 11:43:36.973: E/AndroidRuntime(279): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626) 12-14 11:43:36.973: E/AndroidRuntime(279): at dalvik.system.NativeStart.main(Native Method) 12-14 11:43:36.973: E/AndroidRuntime(279): Caused by: java.lang.reflect.InvocationTargetException 12-14 11:43:36.973: E/AndroidRuntime(279): at android.widget.ImageView.<init> (ImageView.java:108) 12-14 11:43:36.973: E/AndroidRuntime(279): at java.lang.reflect.Constructor.constructNative(Native Method) 12-14 11:43:36.973: E/AndroidRuntime(279): at java.lang.reflect.Constructor.newInstance(Constructor.java:446) 12-14 11:43:36.973: E/AndroidRuntime(279): at android.view.LayoutInflater.createView(LayoutInflater.java:500) 12-14 11:43:36.973: E/AndroidRuntime(279): ... 18 more 12-14 11:43:36.973: E/AndroidRuntime(279): Caused by: java.lang.OutOfMemoryError: bitmap size exceeds VM budget 12-14 11:43:36.973: E/AndroidRuntime(279): at android.graphics.Bitmap.nativeCreate(Native Method) 12-14 11:43:36.973: E/AndroidRuntime(279): at android.graphics.Bitmap.createBitmap(Bitmap.java:468) 12-14 11:43:36.973: E/AndroidRuntime(279): at android.graphics.Bitmap.createBitmap(Bitmap.java:435) 12-14 11:43:36.973: E/AndroidRuntime(279): at android.graphics.Bitmap.createScaledBitmap(Bitmap.java:340) 12-14 11:43:36.973: E/AndroidRuntime(279): at android.graphics.BitmapFactory.finishDecode(BitmapFactory.java:488) 12-14 11:43:36.973: E/AndroidRuntime(279): at android.graphics.BitmapFactory.decodeStream(BitmapFactory.java:462) 12-14 11:43:36.973: E/AndroidRuntime(279): at android.graphics.BitmapFactory.decodeResourceStream(BitmapFactory.java:323) 12-14 11:43:36.973: E/AndroidRuntime(279): at android.graphics.drawable.Drawable.createFromResourceStream(Drawable.java:697) 12-14 11:43:36.973: E/AndroidRuntime(279): at android.content.res.Resources.loadDrawable(Resources.java:1709) 12-14 11:43:36.973: E/AndroidRuntime(279): at android.content.res.TypedArray.getDrawable(TypedArray.java:601) 12-14 11:43:36.973: E/AndroidRuntime(279): at android.widget.ImageView.<init> (ImageView.java:118) 12-14 11:43:36.973: E/AndroidRuntime(279): ... 22 more 12-14 11:43:38.763: I/Process(279): Sending signal. PID: 279 SIG: 9
正如你所看到的,在〜3 MB的位图加载中我特别遇到了一个outofmemory错误…这是没有意义的,因为GC最近运行,没有分配,因为应该使虚拟机在3MB的容量(256 MB).这个256 MB的系统RAM是否只有一小部分实际上是在VM崩溃之前给予的？可能是Bitmap加载过程有自己的内存分配上限吗？
我知道对象池是一个很好的方法来避免游戏循环中的GC,但是不知道什么触发了Dalvik GC,我们仍然对操作系统和Google对性能最佳实践的模糊讨论感到非常信赖.
>可以从代码跟踪GC状态(例如“运行”,“运行”,“完成运行”),以便可以围绕可用内存策略性地计划大量资源分配？我已经看过这个帖子：Determine when the Android GC runs提供了一个有趣的潜在解决方案,但仍然依赖于“伎俩”.我想知道是否有一个支持的API调用,可以在生产代码(而不仅仅是调试)中依赖于跟踪精确状态的垃圾收集器.在某些情况下,System.gc()可能有用,可以检查IF状态;否则,因为它不能承诺立即GC运行,其有用性下降相当多.
> GC总是系统范围内的,还是可以分离线程(如游戏的专用渲染线程),避免GC引起的潜在性能滞后问题？
鉴于以下假设情景：
“我有一个要花费(VM RAM预算)/ 2个字节来实例化的对象,并且我用一个引用立即实例化它.然后,我将该引用清空,使该对象符合GC标准,但当然也不会释放其内存.然后我立即再次实例化对象.
这会使VM崩溃,还是在某种程度上操作系统自动处理这种极端情况,以避免崩溃VM？如果操作系统没有处理它,我会引用它作为一个很好的例子,为什么我上面的问题#2是有效的;如果可以跟踪GC状态,则可以在源中包含逻辑来处理巨大的对象分配问题(实际上比设计糟糕的类更可能是大的资源),通过查看GC加载对象的内存是否在加载之前被释放新的巨大对象实例,并在后台轮询GC时显示小的加载动画.这应该避免应用程序没有响应错误以及合法的内存错误…某种类型的onGC()侦听器将是理想的;可以在本地代码中实现GC监听器,而无需重新构建操作系统内核？
最后,一些源代码…我有正确的想法,以提高性能的Android编程？
活动类别：
package com.ai.ultimap;
//imports omitted...
public class UltiMapActivity extends Activity {
//Housekeeping
private String viewDriverID = "";
private static final int TUTORIAL = 7;
//visuals
private HomeView hv; //home view
private ConfigView cv; //config view
private MapView mv; //map view
private Manual man; //manual view
private int manCount = 0; //tracks the number of times the manual has been called
//with menu button,ignoring button presses unless value is zero
private PathCreator pcv; //path creator view
private MasterGL mgl; //the gl center
private String pending = "Coming soon...";
private PathCreator draw;
private Surfacer morlock;
// Used to handle pause and resume...
private static UltiMapActivity master;
//XML I/O considerations
private String fXML = "mypaths.xml";
private String sXML = "data was not saved properly...?";
private FileOutputStream fos;
private FileInputStream fis;
private FileWriter fw;
private FileReader fr;
private Date theDate = new Date();
private char[] buf = new char[1];
//Feedback stuffs
private FeedbackController Feed;
//tracking you... :)
private WifiStalk stalk;
private long lat;
private long longitude;
//Testing
private DrawView dv;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Log.d("me","ultimap created!");
master = null;
mgl = new MasterGL(this); //revisit this later for versatility
man = new Manual(this);
Feed = new FeedbackController(this);
stalk = new WifiStalk(this);
draw = new PathCreator(this);
hv = new HomeView(this,draw);
try {
BeanCounter bean = new BeanCounter(this);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (XmlPullParserException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
showDialog(TUTORIAL);
}
@Override
public boolean onKeyDown(int keyCode,KeyEvent e){
if (keyCode == 82){
if (viewDriverID.equals("hv")){
hv.removeHV();
}
else if (viewDriverID.equals("cv")){
cv.removeCV();
}
else if (viewDriverID.equals("mv")){
return true;
}
else if (viewDriverID.equals("pcv")){
return true;
}
if(man.getAddedState() == 0){
//Show the manual code...
System.out.println("View we're coming from: " + this.getVDID());
Log.e("me","man.getaddedstate does equal 0,should be about to makeMan");
man.makeMan();
}
else if(man.getAddedState() == 2){
man.removeMan();
man.removeMan2();
man.setAddedState(1);
}
else if(man.getAddedState() == 1){
System.out.println("View we're coming from: " + this.getVDID());
man.addMan();
}
}
return true;
}
@Override
protected Dialog onCreateDialog(int id) {
//alerts ommitted for space
}
//Used to track the semantic context of what the Activity is displaying
//Getters/setters for external access ommitted
@Override
protected void onStart(){
super.onStart();
Log.d("me","ultimap started!");
}
@Override
protected void onPause() {
super.onPause();
Log.d("me","ultimap paused!");
if (mgl.getGLview() != null){
mgl.getGLview().onPause();
}
if (draw.getGLV() != null){
draw.getGLV().onPause();
}
}
@Override
protected void onResume() {
super.onResume();
Log.d("me","ultimap resumed!");
stalk.killListener();
if (mgl.getGLview() != null){
mgl.getGLview().onResume();
Log.d("me","mgl.getGLview is NOT null on resume");
}
else if (mgl.getGLview() == null){
mgl.initGL();
mgl.getGLview().onResume();
Log.d("me","mgl.getGLview is null on resume");
}
if (draw.getGLV() != null){
draw.getGLV().onResume();
Log.d("me","draw.getGLV is NOT null on resume");
}
else if (draw.getGLV() == null && draw.getHGL() != null){
draw.pcvInit();
Log.d("me","draw.getGLV is null on resume");
}
if (hv.getMV() != null && hv.getMV().getGLV() != null){
hv.getMV().getGLV().onResume();
Log.d("me","map.getGLV is NOT null on resume");
}
else if (hv.getMV() != null && hv.getMV().getGLV() == null &&
hv.getMV().getHGL() != null){
hv.getMV().mvInit();
Log.d("me","map.getGLV is null on resume");
}
}
@Override
protected void onStop() {
super.onStop();
//Feed.getSP().release();
Log.d("me","ultimap stopped!");
}
@Override
protected void onRestart(){
super.onRestart();
Log.d("me","ultimap restarted!");
if (mgl != null){
mgl.initGL();
}
}
@Override
protected void onDestroy(){
super.onDestroy();
Log.d("me","ultimap destroyed!");
mgl.disposeTextures();
if (Feed.getSP() != null && Feed.getSID() != 0 && Feed.getLoaded() ==
true){
Feed.getSP().unload(Feed.getSID());
Feed.getSP().release();
}
}
}
教程视图管理器类：
/*
* This class defines an in-app manual which is callable/dismissable
* in a non-invasive way...
*
* http://www.codeproject.com/KB/android/ViewFlipper_Animation.aspx
*http://developer.android.com/reference/android/widget/
*ViewFlipper.html#ViewFlipper%28android.content.Context%29
* http://developer.android.com/resources/articles/avoiding-memory-leaks.html
*/
package com.ai.ultimap.views;
//imports ommitted
public class Manual extends View implements OnItemClickListener{
private UltiMapActivity hUMA;
private ListView lv1;
private ListAdapter la;
private LayoutInflater mInflater;
private Vector<RowData> data;
private TextView tv;
private RelativeLayout holderRL;
private View v;
private View v2;
private int addedState = 0; //tracks whether or not a view has been instantiated,//and if so whether or not it is the currently visible view
private int addedState2 = 0;
//Grid View stuff
private GridView helpGrid;
//ViewFlipper stuff
private ViewFlipper vf;
private TextView tutTV;
private String mapTutString = "Map View Tutorial Part: ";
private String pcTutString = "Path Creator Tutorial Part: ";
private String tutType;
private TextView counterTV;
private int partCounter = 1;
private float oldTouchValue = 0.0f;
private boolean searchOk = true;
private ImageView floatingImage;
public Manual(UltiMapActivity hAct){
super(hAct);
hUMA = hAct;
holderRL = new RelativeLayout(hUMA);
v = new View(hUMA);
floatingImage = new ImageView(hUMA);
}
//Here we summon and populate the grid view
public void makeMan(){
if (addedState == 0){
Log.e("me","in makeMan");
mInflater = (LayoutInflater)
hUMA.getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
hUMA.addContentView(holderRL,new
LayoutParams(LayoutParams.MATCH_PARENT,LayoutParams.MATCH_PARENT));
v = mInflater.inflate(R.layout.helpgrid,holderRL,false);
helpGrid = (GridView) v.findViewById(R.id.manGV);
helpGrid.setAdapter(new ImageAdapter(hUMA));
hUMA.addContentView(v,LayoutParams.MATCH_PARENT));
helpGrid.setOnItemClickListener(this);
addedState = 2;
}
}
public void addMan(){
if (v != null && addedState == 1){
v.setVisibility(VISIBLE);
v.bringToFront();
addedState = 2;
}
}
public void addMan2(){
if (v2 != null && addedState2 == 1){
v2.setVisibility(VISIBLE);
v2.bringToFront();
addedState2 = 2;
}
}
public void removeMan(){
if (v != null && addedState == 2){
v.setVisibility(GONE);
addedState = 1;
String s = hUMA.getVDID();
if (s.equals("hv")){
hUMA.getHome().addHV();
Log.d("me","add hjomeview called from anual");
Log.d("me","hv addedstate : " +
hUMA.getHome().getAddedState());
}
else if (s.equals("cv")){
hUMA.getConfig().addCV();
}
else if (s.equals("mv")){
hUMA.getHome().getMV().mvInit();
}
else if (s.equals("pcv")){
hUMA.getDraw().pcvInit();
}
}
}
public void removeMan2(){
if (v2 != null && addedState2 == 2){
v2.setVisibility(GONE);
addedState2 = 1;
String s = hUMA.getVDID();
if (s.equals("hv")){
hUMA.getHome().addHV();
Log.d("me","add hjomeview called from manual");
Log.d("me","hv addedstate : " +
hUMA.getHome().getAddedState());
}
else if (s.equals("cv")){
hUMA.getConfig().addCV();
}
else if (s.equals("mv")){
hUMA.getHome().getMV().mvInit();
}
else if (s.equals("pcv")){
hUMA.getDraw().pcvInit();
}
}
}
//addedstate getters and setters ommitted for space
@Override
public boolean onTouchEvent(MotionEvent touchevent) {
switch (touchevent.getAction())
{
case MotionEvent.ACTION_DOWN:
{
System.out.println("received a touch down at " + touchevent.getX()
+ "," + touchevent.getY());
oldTouchValue = touchevent.getX();
if(this.searchOk==false) return false;
float currentX = touchevent.getX();
if (currentX > (vf.getWidth()/2))
{
vf.setInAnimation(AnimationHelper.inFromRightAnimation());
vf.setOutAnimation(AnimationHelper.outToLeftAnimation());
vf.showNext();
if (partCounter <= 3 && partCounter >= 1){
partCounter++;
}
else if (partCounter == 4){
partCounter = 1;
}
else{
Log.e("me","partCounter got past 4...");
}
if(tutType.equals("map")){
counterTV.setText(mapTutString + partCounter);
}
else if(tutType.equals("pc")){
counterTV.setText(pcTutString + partCounter);
}
else{
Log.e("me","not getting valid tutType string");
}
}
if (currentX <= (vf.getWidth()/2))
{
vf.setInAnimation(AnimationHelper.inFromLeftAnimation());
vf.setOutAnimation(AnimationHelper.outToRightAnimation());
vf.showPrevIoUs();
if (partCounter >= 2 && partCounter <= 4){
partCounter--;
}
else if (partCounter == 1){
partCounter = 4;
}
else{
Log.e("me","partCounter got below 1...");
}
if(tutType.equals("map")){
counterTV.setText(mapTutString + partCounter);
}
else if(tutType.equals("pc")){
counterTV.setText(pcTutString + partCounter);
}
else{
Log.e("me","not getting valid tutType string");
}
}
break;
}
case MotionEvent.ACTION_UP:
{
//nothing to do here
}
}
return false;
}
public void setUserText(String str){
tv.setText(str);
}
private class CustomTV extends TextView{
private String content = "";
public CustomTV(Context c,String str){
super(c);
content = str;
this.setText(content);
}
}
/**
* Data type used for custom adapter. Single item of the adapter.
*/
private class RowData {
protected String mItem;
protected String mDescription;
RowData(String item,String description){
mItem = item;
mDescription = description;
}
@Override
public String toString() {
return mItem + " " + mDescription;
}
}
private class CustomAdapter extends ArrayAdapter<RowData> {
public CustomAdapter(Context context,int resource,int textViewResourceId,List<RowData> objects) {
super(context,resource,textViewResourceId,objects);
}
@Override
public View getView(int position,View convertView,ViewGroup parent) {
ViewHolder holder = null;
//widgets displayed by each item in your list
TextView item = null;
TextView description = null;
//data from your adapter
RowData rowData= getItem(position);
//we want to reuse already constructed row views...
if(null == convertView){
convertView = mInflater.inflate(R.layout.custom_row,null);
holder = new ViewHolder(convertView);
convertView.setTag(holder);
}
holder = (ViewHolder) convertView.getTag();
item = holder.getItem();
item.setText(rowData.mItem);
description = holder.getDescription();
description.setText(rowData.mDescription);
return convertView;
}
}
/**
* Wrapper for row data.
*
*/
private class ViewHolder {
private View mRow;
private TextView description = null;
private TextView item = null;
public ViewHolder(View row) {
mRow = row;
}
public TextView getDescription() {
if(null == description){
description = (TextView) mRow.findViewById(R.id.cBox);
}
return description;
}
public TextView getItem() {
if(null == item){
item = (TextView) mRow.findViewById(R.id.cBox2);
}
return item;
}
}
@Override
public void onItemClick(AdapterView<?> arg0,View arg1,int position,long id) {
v.setVisibility(GONE);
if (addedState2 == 0){
hUMA.addContentView(this,DefineLayoutParams.getParams(DefineLayoutParams.getMM()));
//this is why the onTouch only starts lsitening at this point
if (position == 0){
v2 = mInflater.inflate(R.layout.flipper,false);
vf = (ViewFlipper) v2.findViewById(R.id.manFlipperVF);
tutTV = (TextView) v2.findViewById(R.id.manDescriptionTV);
counterTV = (TextView) v2.findViewById(R.id.mapviewtutCounterTV);
tutTV.setText("Map View Instructions: ...");
counterTV.setText(mapTutString + partCounter);
tutType = "map";
}
else if (position == 1){
v2 = mInflater.inflate(R.layout.flipperpc,false);
vf = (ViewFlipper) v2.findViewById(R.id.manFlipperpcVF);
tutTV = (TextView) v2.findViewById(R.id.manDescriptionpcTV);
counterTV = (TextView) v2.findViewById(R.id.manFlipperCounterpcTV);
tutTV.setText("Path Creator Tutorial:...");
counterTV.setText(pcTutString + partCounter);
tutType = "pc";
}
addedState2 = 2;
hUMA.addContentView(v2,DefineLayoutParams.getParams(DefineLayoutParams.getWW()));
}
else if(addedState2 == 1){
v2.setVisibility(VISIBLE);
addedState2 = 2;
}
}
public String getTutType(){
return tutType;
}
}
教程视图Flipper XML：
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
>
<ScrollView
android:id="@+id/manDerscriptionSV"
android:layout_width="match_parent"
android:layout_height="200px"
>
<TextView
android:id="@+id/manDescriptionTV"
android:text="Coming Soon..."
android:layout_width="match_parent"
android:layout_height="wrap_content"
/>
</ScrollView>
<TextView
android:id="@+id/mapviewtutCounterTV"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Map View Tutorial Part: "
android:gravity="center"
android:layout_below="@id/manDerscriptionSV"
/>
<ViewFlipper
android:id="@+id/manFlipperVF"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="@id/mapviewtutCounterTV"
>
<ImageView
android:id="@+id/mapviewtut1"
android:src="@drawable/mapviewtutflipper1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
/>
<ImageView
android:id="@+id/mapviewtut2"
android:src="@drawable/mapviewtutflipper2"
android:layout_width="match_parent"
android:layout_height="wrap_content"
/>
<ImageView
android:id="@+id/mapviewtut3"
android:src="@drawable/mapviewtutflipper3"
android:layout_width="match_parent"
android:layout_height="wrap_content"
/>
<ImageView
android:id="@+id/mapviewtut4"
android:src="@drawable/mapviewtutflipper4"
android:layout_width="match_parent"
android:layout_height="wrap_content"
/>
</ViewFlipper>
</RelativeLayout>
谢谢,
CCJ
解决方法
@H_403_35@
- What exactly triggers GC in Android?
这是SDK开发人员不用担心的内部实现细节.
@H_403_35@Other VM implementations I’ve seen usually allow for a certain percentage of system memory to be allocated to an application before their GC receives a signal to run.
我会接受你的话. Java不这样做. JVM不关心存在多少系统内存 – 它最多仅关心其自己的VM的潜在堆大小(例如,-Xmx).
@H_403_35@Scanning the following LogCat however seems to show Dalvik GC running at least in part quite often
正确.特别是在较新的Android版本上,GC以自己的线程同时运行,而不是先前采取的停止世界的方法.
@H_403_35@This doesn’t make sense to me since GC recently ran and nothing allocated since should have brought the VM within 3MB of capacity (256 MB).
您的VM极不可能拥有256MB的堆空间.根据您的设备,它可能低至16MB.
此外,Android没有压缩GC算法,因此即使可能有3MB以上的可用性,您可能没有连续的3MB块.
这就是为什么要重新利用()您的Bitmap对象或尝试重用它们(例如,BitmapOptions的映射,添加在API级别11中).
此外,您可以使用DDMS创建堆转储和MAT检查它,更准确地确定您的内存在哪里,以及谁持有什么.这在Android 3.0上更好,因为MAT将能够更准确地在这些版本中报告Bitmap内存.
@H_403_35@Is there only a small percentage of that 256 MB system RAM which is actually given to the VM before it crashes?
是.它被称为堆. Android设备的堆大小限制.通常情况下,它的范围是16-48MB,具体取决于Android操作系统版本和屏幕分辨率.
@H_403_35@Could it be that the Bitmap loading process has its own memory allocation cap?
不,它可以从相同的堆大小预算中起作用.从Android 3.0开始,它真的将与其他Dalvik对象使用的内存一样加载 – 以前,它使用堆外部的系统RAM块,但是这个空间是根据堆的大小预算计算的.
@H_403_35@but without knowing EXACTLY what triggers Dalvik GC we’re still placing an awful lot of faith in the OS and Google’s vague discussions of performance best-practices
生活就像他们说的那样继续下去.
@H_403_35@Can the GC state (e.g. ‘about to run’,‘running’,‘finished running’) be tracked from code so that large resource allocations might be planned strategically around available memory? … I’d like to know if there is a supported API call somewhere which can be relied upon in production code (not just debug) to track the precise state of the garbage collector.
没有.
@H_403_35@Is GC always system-wide,or can separate threads (such as a dedicated rendering thread for a game) escape the potential performance lag issues caused by GC?
GC对于任何虚拟机来说都不是“系统范围”. GC始终位于VM内.
在较新的Android版本中,GC是并发的,因此在正常情况下不会实质阻止任何线程.在旧版本的Android上,GC是世界上的一切,将影响所有的线程. Android 3.0的变化肯定是适用的 – 对于并发GC是否已经适用于Android 2.3,我的记忆是模糊的.有一个2011年Google I | O的Android内存管理演示文稿,您可能希望观看.
@H_403_35@Would this crash the VM or is there some way the OS handles such extreme situations automatically to avoid crashing the VM?
在升级OutOfMemoryException之前,Android应强制立即使用GC.这种情况符合我以前的副标题不是“正常情况”.
