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Android Note.md

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93 lines (92 loc) · 6.3 KB

  • setTextSize(int unit, int size)TypedValue.COMPLEX_UNIT_PX : PixelsTypedValue.COMPLEX_UNIT_SP :Scaled PixelsTypedValue.COMPLEX_UNIT_DIP : Device Independent Pixels

  • 但是textview中getTextSize返回值是以像素(px)为单位的，而setTextSize()是以sp为单位的

  • 异步加载里不能settext!

  • alrmmanagement 记得加userpermission

  • 判断密码两次输入是否相等 trim();

  • setUserVisibleHint is only accessible in FragmentPageAdapter

  • scrollview 里嵌套listview gridview 只显示单行

  • setImageResource是同步的，资源图片的读取和解码都是在主线程中进行的。setImageDrawable是异步的。加载速度的区别。setImageResource要快于setImageDrawable和setImageBitmap.

  • found carriage return (\r) without corresponding newline (\n) ctrl A+X+V+S

  • listview adapter visible set visible 或者gone必须！

  • softinput manifext resize

  • cast (youractivity)getActivity()

  • inflater(,,false) the specific child already has a parent

  • translate fromXDelta 100% 与100%p

  • FragmentPagerAdapter getFragment private String getFragmentTag(int fragmentPosition) { return "android:switcher:" + R.id.pager + ":" + fragmentPosition; }

  • addheadview setonitemtclick pisition-1 or parent.getItemAtPosition(position),onclick不会错；

  • Math.round(TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 210, context.getResources().getDisplayMetrics()));

  • view.getloctiononscreen

  • getChildFragmentManager!!nested fragment

  • transaction.addToBackStack after u remove or replace a fragment so that user can navigate back

  • context.getFileDir() or gerCacheDir()

  • Alternatively, you can call openFileOutput() to get a FileOutputStream that writes to a file in your internal directory.

  • When the user uninstalls your app, the Android system deletes the following: All files you saved on internal storage All files you saved on external storage using getExternalFilesDir().

  • queryIntentActivities() before send an implicit intent

  • textview.getpaint().setflags(Paint.UNDERLINE_TEXT_FLAGS)

  • enabled and clickeable if clickable false then long click still fuctions

  • dialog u must setOnKeyListener rather than override onKeyDown

  • onkeydown cannot listene back key ,u can use onbackpressed LOL

  • setresult should before super.onBackPressed in onBackPressed

  • API 18 android - 3 Bluetooth low energy

  • seekbar progressdrawable layer-list clip maxheight minheight

  • screen size getActivity().getWindowManager().getDefaultDisplay().getSize(new Point());

  • start an activity outside an activity should set FLAG_ACTIVITY_NEW_TASK

  • android - 0杀死应用进程后并不会杀死应用内的闹钟

  • PowerManager.PARTIAL_WAKE_LOCK cannot wake up the screen use SCREEN_DIM_WAKE_LOCK or SCREEN_BRIGHT_WAKE_LOCK; But the best choice is to user PATIEAL_WAKE_LOCK to wake up the screen then in the activity set WindowManger.LayoutParams.FlAG_KEEP_SCREEN_ON

  • 以后 start Intent(String) 必须加上setPackageName();

  • parcel marshall和unmarshall前都要加上setDataPosition;

  • Calendar getDayOfWeek 妙法 (getDayOfweek+5)%7

  • contentProvider insert时 ContentValues mValues = new ContentValues(values);but why

  • when u comes with View1 cannot be cast into View2,u may need to delete the R file and recreate it;

  • dialog alginleft problem :getWindow().setlayout(match_parent,wrap_content); wrong

  • seekbar thumb if set offset=0 then u cannot get the center position of thumb

  • 如int i = 1000000; long j = 1000+i100000000000; !!!bug,i100000000000超过i最大值会显示为最大值

  • button with image and text

android:drawableLeft="@drawable/icon_uploading_gray"
android:drawablePadding="10dp"
android:gravity="left|center_vertical"
  • return type="json" timestamp??? @JSON(format = "yyyy-MM-dd HH:mm:ss")
  • do things like setResult() before super.onbackPressed(); or you will get default resultcold(0)
  • preference.editor.commit后立刻离开activity可能会失败，毕竟读写需要时间
  • data/data/pachage need phone root to show
  • visibiliy = gone 以及 无法显示（parent 太小） 很可能得到的getheight 和getwidth 都是 0 ；
  • view- getViewTreeObserver().addOnGlobalLayoutListener getheight before show
  • relativelayout 里的 imageview ，在设置relativeLayout 宽高后后zoom效果
  • service intent must be explicit. just setPackage both start and stop
  • android weight 在match parent 和wrap_content 时的不同
  • android bugs nested fragment
  • edittext 对于小数有可能以小数点开始或者结尾，注意判断
  • editext onEditorAction
  • using dialogfragment other than dialog
  • never and never put a scrollable view inside another , you foolish fucking fish!
  • drawlayout.setlockmode
  • recyclerview StaggeredGridLayoutManager
  • app:layout_anchor app:layout_anchorGravity for floatactionbutton
  • arraylist<>(size) the size doestn't mean this list's size but its max size u fool!
  • navigationView.getMenu().getItem(0).setChecked(true);
  • tinmanager
  • d better not to usr list = list2; rather list.clear(); list.addAll()
  • custom style save in style.xml
  • Relative width wrap_content 里的 view width match_parent 似乎无效 换成lienearLayout 成功 难道是linearlayoutmanager 的作用?
  • get drawble from res then setColorFilter PorterDuff
  • list preference only support string array remember to convert after got
  • listpreference forbid dialog overide showDialog
  • after setSupportActoolbar the toolbar's setTitle doesnt work,use getSupportActionBar.setTitle instead. But when u have a navigationDrawable it seems still work
  • settheme should called before setContentView so when after changed ur activity in back state may need to be recreated
  • settheme must call before supe.create or some attr such as windowbackground wont work 145
  • when use weight be carefull of odp wrap_content and match_parent
  • dialogfragment match_parent setStyle(DialogFragment.STYLE_NO_TITLE,android.R.style.Theme_Holo_Light_Dialog_NoActionBar_MinWidth)
  • customview extends viewgroup,addview(child) in onmeasure and onLayout calculate and set child's size call:getChildAt(),child.onMeasure ,child.onLayout
  • isInEditMode()
  • cardview cardBackgroundColor should be set when using whole context theme background color
  • sometimes need parcel to store sth maybe u can try bundle
  • setBackGround(null) maybe cause resize problem
  • 注释换行

  • RelativeLayout.LayoutParams addRule(RelativeLayout.。。)
  • android studio ALT+TAB perfect!!!!