Common optimization items

Handwriting , Write where you want , Irregular change

Glide

1. Use simpleTag And so on into() Object time , Need to set up override() Property to avoid loading images that are too large OOM
2. For a fixed area, display a large image , If the display can be intercepted, the intercepted part can be displayed in the control , Use Bitmap.createBitmap(scaleBitmap, 0, 0, w, h) Tailoring
3. Available for large drawings BitmapRegionDecoder Perform a regional display , Refer to the large picture to show demo

onDestroy Delay the

1. because onstop And onDestroy The execution is in the main thread IdleHandle Execute under callback , If the main thread has unfinished tasks , You cannot immediately call back onstop And onDestroy, but onReume Will be delayed 10s Then call the exit method as a strategy to reveal the details
2. Solution 1 ： Find the blocked thread , Generally, it is caused by the fact that the animation does not stop logging off when jumping or closing the page, or some monitoring is not cancelled
3. Solution 2 ： If the cause of the blockage is difficult to find , Can be in onPause Judge isFinish（） To decide whether to recycle resources , Execute the code to be recycled in advance , Simple and effective , The possible hidden trouble lies in onStop,onDestroy The object in is recycled in advance, resulting in a null pointer , And that is getLifecycle().addObserver（） The rhythm of bound object life cycle execution is inconsistent
4. Reference resources Check what the main thread does

Resource pictures

1. Try to add multi-resolution pictures , Otherwise, it may cause the picture to occupy too much memory on the HD device
2. Use imageAsset To make the ic_launcher The picture is covered with a transparent layer , You may not get the desired shape when you crop the display , Use other png Pictures can be substituted
3. Updating the progress bar during file download may cause the interface to change because of too frequent callback ddos, It can be done by handle Controls the minimum granularity of the refresh

WebView Optimize

1. In the use of WebView In more frequent projects , A can be initialized in advance WebView To be used , Direct reference when required ,app Destroy on exit , For details, please refer to H5 Realize second on
2. The destruction WebView

@Override
protected void onDestroy() {
    
    super.onDestroy();
    //  First remove... From the parent control WebView
    mWebViewContainer.removeView(mWebView);
    mWebView.stopLoading();
    mWebView.getSettings().setJavaScriptEnabled(false);
    mWebView.clearHistory();
    mWebView.removeAllViews();
    mWebView.destroy();
}

RecyclerView

1.NestScrollView And RecyclerView Nesting can lead to recycler It can't be reused , Cause sliding jamming
Sliding nested processing
2. Paging query causes duplicate data resolution due to new data The main idea is to get in and out of the last ID To the backstage , The background always takes the first page when taking values , At the same time, compare ID Size confirms the page data , Avoid inaccurate data caused by deletion or insertion

Dialog

1. dialog Used in editText No cursor display is used android:textCursorDrawable="@drawable/my_cursor" Property to set

<shape xmlns:android="http://schemas.android.com/apk/res/android">
    <solid android:color="@color/green" />
    <size android:width="1dp" />
</shape>

Commonly used list choice

1. ArrayMap

ArrayMap The use of HashMap It's the same . When the data structure is <key,value> When , You can use ArrayMap replace .
But compared to HashMap,ArrayMap stay Android Is not always efficient . When the amount of data is large （ Hundreds of ） after , Its performance will degrade at least 50%. therefore , When the amount of data is small , Use ArrayMap The efficiency is quite high

2. SparseArray

Also with a <Key,Value> Yes
SparseIntArray： When map The structure of is Map<Integer,Integer> When you use , More efficient .
SparseBooleanArray: When map The structure of is Map<Integer,Boolean> When you use , More efficient .
SparseLongArray: When map The structure of is Map<Integer,Long> When you use , More efficient .
LongSparseArray: When map The structure of is Map<Long,Value> When you use , More efficient .

3. ArraySet

and ArrayMap For a similar purpose , To improve HashSet The efficiency of . How to use it HashSet similar

4. String And list< String > Fast inter rotation Need to import .guava tool kit compile 'com.google.guava:guava:26.0-jre'

list->String : String s=Joiner.on(",").join(list);
String->list: List< String > listSplitter.on("-").splitToList(str)

String

1. Display with % Characters may be reported UnknownFormatConversionException,% Need to escape %%