Android Training精要(四) Intent注意事项

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Android Training精要(四) Intent注意事项

判断有处理Intent的Activity PackageManager packageManager = getPackageManager(); List<ResolveInfo> activities = packageManager.queryIntentActivities(mapIntent, 0); boolean isIntentSafe = activities.size() > 0; // Start an activity if it's safe if (isInt…

Android Training精要（六）如何防止Bitmap对象出现OOM

1.使用AsyncTask異步加載bitmap圖片避免OOM: class BitmapWorkerTask extends AsyncTask<Integer, Void, Bitmap> { private final WeakReference<ImageView> imageViewReference; private int data = 0; public BitmapWorkerTask(ImageView imageView) { // Use a WeakRefe…

Android Training精要（一）ActionBar上级菜单导航图标

Navigation Up(ActionBar中的上级菜单导航图标) 在android 4.0中,我们需要自己维护activity之间的父子关系. 导航图标ID为android.R.id.home @Override public boolean onOptionsItemSelected(MenuItem item) { switch (item.getItemId()) { case android.R.id.home: // This is called when the Home (Up…

Android Training精要（七）内存管理

在2.3.3及以下版本: 通過定義兩個整形變量來檢測bitmap是否display過或者已經在緩存中下面的代碼當bitmap滿足兩個條件就被回收掉: 1. 兩個整形變量都變為0 2. bitmap不為null並且還沒有被回收掉 private int mCacheRefCount = 0; private int mDisplayRefCount = 0; ... // Notify the drawable that the displayed state has changed. // K…

Android Training精要（二）開啟ActionBar的Overlay模式

在3.0上的實現 <resources>  <style name="CustomActionBarTheme" parent="@android:style/Theme.Holo"> <item name="android:windowActionBarOverlay">true<…

Android Training精要（五）讀取Bitmap對象實際的尺寸和類型

讀取Bitmap對象實際的尺寸和類型 BitmapFactory.Options options = new BitmapFactory.Options(); options.inJustDecodeBounds = true; BitmapFactory.decodeResource(getResources(), R.id.myimage, options); int imageHeight = options.outHeight; int imageWidth = options.outW…