How Android interprets #null keyword in layouts? - java

I was digging in sources of Android by looking for an answer of how system recognizes #null keyword that mentioned in a layout. For instance,
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:background="#null"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
So far I followed this route:
TypedArray#getDrawable(int index)
ResourcesImpl#getValue(#AnyRes int id, TypedValue outValue, boolean resolveRefs)
AssetManager#getResourceValue(#AnyRes int resId, int densityDpi, #NonNull TypedValue outValue,boolean resolveRefs)
AssetManager#loadResourceValue(int ident, short density, TypedValue outValue,boolean resolve)
I tried to find in source code of JNI implementation of AssetManager loadResourceValue method, but I have not succeeded.
I would appreciate if anyone can point out how Android resolves #null tag.
Thanks in advance!

You were searching in AssetManager frontend that is exposed via NDK. There are no JNI functions at all. JNI wrapper for android.util.AssetManager is here.
ResTable class is used for actual parsing and resolving. If you dig a bit deeper - you can find lines where #null is handled.

Related

Setting EditText Cursor Color With Reflection Method

I've been using a reflection method to set my EditText's cursor colors programmatically which I found from this answer (I also tried this answer). However, after some recent updates, can't remember exactly when, that method no longer works, I assume that Android has probably changed something in the TextView class. Anyways, can someone help me with this? Are there now new field names for mCursorDrawableRes and mCursorDrawable, or is that whole method invalid and needs to be implemented another way now?
Update: I just found out that this method stopped working only on Android P, on the previous versions, it still works.
Update 2: I solved problem myself, check the answer if you are stuck as well.
OK, after digging into the Android Pie Source Code, I found out that Google has changed mCursorDrawable to mDrawableForCursor, and also changed its type from a two element Drawable array to simply Drawable, so I made some changes based on the original reflection method, and now it works for Android P:
public static void setEditTextCursorColor(EditText editText, int color) {
try {
// Get the cursor resource id
Field field = TextView.class.getDeclaredField("mCursorDrawableRes");
field.setAccessible(true);
int drawableResId = field.getInt(editText);
// Get the editor
field = TextView.class.getDeclaredField("mEditor");
field.setAccessible(true);
Object editor = field.get(editText);
// Get the drawable and set a color filter
Drawable drawable = ContextCompat.getDrawable(editText.getContext(), drawableResId);
drawable.setColorFilter(color, PorterDuff.Mode.SRC_IN);
// Set the drawables
if(Build.VERSION.SDK_INT >= 28){//set differently in Android P (API 28)
field = editor.getClass().getDeclaredField("mDrawableForCursor");
field.setAccessible(true);
field.set(editor, drawable);
}else {
Drawable[] drawables = {drawable, drawable};
field = editor.getClass().getDeclaredField("mCursorDrawable");
field.setAccessible(true);
field.set(editor, drawables);
}
//optionally set the "selection handle" color too
setEditTextHandleColor(editText, color);
} catch (Exception ignored) {}
}
Side note, I really wish Google could just add a public method like setCursorDrawable() or something like that, that would've been much easier.
Unfortunately, Google have not exposed xml attributes to tint, or methods to set, the drawables for these even in the compatability libraries, so currently the only way to dynamically set them is via reflection as described.
However, you can set the drawables in xml, and if you just want to tint the existing material design drawables this can be done by tinting xml for the text select handles as they are bitmap drawables, but the cursor drawable is an inset drawable, so will have to be recreated from the source code.
The drawables used are:
R.drawable.abc_text_select_handle_left_mtrl_light
R.drawable.abc_text_select_handle_middle_mtrl_light
R.drawable.abc_text_select_handle_right_mtrl_light
R.drawable.abc_text_cursor_material
You can create tinted versions of the text select handle drawables like this:
<bitmap xmlns:android="http://schemas.android.com/apk/res/android"
android:src="#drawable/abc_text_select_handle_left_mtrl_light"
android:tint="#color/my_text_select_handle_color" />
<bitmap xmlns:android="http://schemas.android.com/apk/res/android"
android:src="#drawable/abc_text_select_handle_middle_mtrl_light"
android:tint="#color/my_text_select_handle_color" />
<bitmap xmlns:android="http://schemas.android.com/apk/res/android"
android:src="#drawable/abc_text_select_handle_right_mtrl_light"
android:tint="#color/my_text_select_handle_color" />
The cursor drawable can be recreated from the source code like this:
<inset xmlns:android="http://schemas.android.com/apk/res/android"
android:inset="2dp">
<shape
android:tint="#color/my_text_cursor_color"
android:shape="rectangle">
<size
android:height="2dp"
android:width="2dp" />
<solid
android:color="#color/white" />
</shape>
</inset>
Place these in the drawables folder and reference them in your AppCompatEditText xml definition using:
android:textCursorDrawable
android:textSelectHandle
android:textSelectHandleLeft
android:textSelectHandleRight
and voila, custom colored cursor and select handles that exactly match the default material design version that avoids reflection so won't cause warnings or errors.

Nougat is much slower when compared to marshmallow

I've been making an android game and I noticed that it runs more than twice as slow on Nougat than on Marshmallow. In fact I figured out that between any two points in my code it seems to have roughly the same increase in time.
So I made a test application that, when the back button is pressed, does a test but I got roughly the same result again (code is below). I tested this using two android virtual devices(see the code for an average time in ms that was recorded) but I initially noticed it because my tablet got updated to nougat so it isn't AVD specific.
I'm stumped as to what is causing this. Some ideas I've had are the following:
The compiler isn't optimizated for nougat (api min is 15 and target is 25 and I'm building with sdk tools 25.0.2). Seems unlikely to me since it would be a pretty widespread issue that google would immediately fix.
The OS is using more resources and thus there are less left over for my game. Unlikely since this shouldn't account for a 2X decrease in speed.
The OS is added in a smaller limit for CPU usage. Maybe I have to request to be high priority or something alike however I'd expected clear documentation so also unlikely.
Android studio's settings for me aren't optimal. This one seems the most likely to me but I can't find anything that helps me yet.
Any insights or reproductions are appreciated! Thanks.
MainActivity
package com.example.nickgkg.test;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.TextView;
public class MainActivity extends AppCompatActivity{
TextView text;
long time = 0;
#Override
protected void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
text = (TextView)this.findViewById(R.id.text);
}
#Override
public void onBackPressed(){
//API 24(nougat) vs API 23(marshmallow)
//API 25 performs the same as API 24 so I didn't include it
long t=System.nanoTime();
if(false){//Toggle this to change the test
float garbage;
for(int i=0;i<100000000;i++)
garbage=i*27/2200f;
//API 24:710ms vs API 23:620ms
}else{
for(int i=0;i<1000000;i++)
something();
//API 24:320ms vs API 23:120ms
}
time=System.nanoTime() - t;
text.setText(time/1000000f+"ms");
}
private void something(){
//BLANK function call
}
}
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/activity_main"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
tools:context="com.example.nickgkg.test.MainActivity">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Hello World!"
android:id="#+id/text"/>
</RelativeLayout>
Updating android studio fixed the problem
(updated from 2.2 to 2.3). I'm still not sure why this happened in the first place but I think it might have been that the debug builds for nougat weren't being optimized as much as the debug builds for marshmallow. On another note; perhaps if I tested with release builds instead of debug builds then I would never have got this issue (haven't tested this though).

Android Java: Buttons and TextViews not showing up when added via Java (to existing XML layout)

OK, I'm tearing my hair out.
I have a simple default relative layout XML for my main activity, and defined a LinearLayout in the XML as well. In my Java code, I added a LinearLayout row, orientation horizontal, and added it to the XML Linearlayout (which I found by ID). When I then added Buttons or Textviews to that layour row, they showed up perfectly.
However, when I attempted to do the same thing in another activity, I can't get the TextViews or Buttons to show up at all. I originally had a background image and tried adding my Buttons and TextViews directly to the root RelativeLayout (foundById), with plans to move them around by .setX and .setY, but I took away the background and reverted to referencing a specific Linearlayout like my main Activity (for testing purposes, to remove any anomalies)and it still won't show them. I have re-arranged and tested forever and can not see what I'm missing.
Here's my current XML (stripped down for testing):
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/activity_open_template"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
tools:context="com.mystuff.stupidapp.OpenTemplateActivity">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:id="#+id/openTemplateMain">
</LinearLayout>
</RelativeLayout>
...and here's the current code (also stripped down):
public class OpenTemplateActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_open_template);
final Resources res = getResources();
Intent intent = getIntent();
String fileName = intent.getStringExtra(MainActivity.EXTRA_FILENAME);
DisplayMetrics displaymetrics = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(displaymetrics);
int screenHeight = displaymetrics.heightPixels;
int screenWidth = displaymetrics.widthPixels;
LinearLayout.LayoutParams rowLayoutParams = new LinearLayout.LayoutParams(
LinearLayout.LayoutParams.MATCH_PARENT,
LinearLayout.LayoutParams.MATCH_PARENT, 1.0f);
LinearLayout llMain = new LinearLayout(this);
llMain.setOrientation(LinearLayout.HORIZONTAL);
LinearLayout llMainParent = (LinearLayout) findViewById(R.id.openTemplateMain);
llMainParent.addView(llMain);
Button bTest = new Button(this);
bTest.setText("TESTB");
llMain.addView(bTest);
//other code below unrelated.
}
}
Ideas, anyone? Please?
Answering my own question for those with a similar issue:
Turns out the APK was stuck, but only with code. Meaning any changes to the XML template (adding/removing Text or buttons or backgrounds) would reflect on the test device when I hit Play or Debug. But any changes to the code would NOT be reflected. I noticed this when I changed the tags in my debug logging and they were not reflected in the logs. I also noticed a Toast-like popup saying something about the app being dismissed manually and to re-run via IDE, but it didn't stay around long enough for a good look.
Clearing the cache and data, the uninstalling the app, then re-launching via the IDE play, fixed the issue. Code changes are now being reflected as expected, and code-created views are being shown as well.
You can prevent this or something similar from happening in the future by disabling the instant run feature in Android Studio: https://stackoverflow.com/a/35169716/3662251
Instant run basically incrementally compiles your code and only pushes the changes to the device. Unfortunately in its current state inconsistencies between code and runtime happen quite often and can lead to many wasted hours of bug hunting when that bug was actually introduced by instant run.

Another Resources$NotFoundException on setContentView

There are lots of Resources$NotFoundException questions on Stack Overflow and I've reviewed them and tried the various suggestions to no avail.
I had a perfectly working layout to display some graphics with some buttons underneath and I modified some of the buttons and started to get this error. I couldn't see anything wrong with my changes but just to narrow it down I deleted ALL the buttons, so now I just have a LinearLayout with an ImageView and I'm still getting the error. My Java:
try {
setContentView(R.layout.graphics);
}
catch (Exception e) {
Log.d("DGraphActivity", "setContentView crash");
}
My XML:
<?xml version="1.0" encoding="UTF-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal">
<ImageView
android:id="#+id/image2"
android:layout_width="0px"
android:layout_weight="2"
android:layout_height="match_parent"
android:scaleType="fitCenter">
</ImageView>
</LinearLayout>
The error says android.content.res.Resources$NotFoundException: Resource ID #0x7f030005.
In the R.java file that resource is identified with the graphics . . .
public static final class layout {
public static final int addcomment=0x7f030000;
public static final int areyousure=0x7f030001;
public static final int downarrow=0x7f030002;
public static final int downleftarrow=0x7f030003;
public static final int downrightarrow=0x7f030004;
public static final int graphics=0x7f030005;
public static final int infofromoperator=0x7f030006;
I deleted the gen folder and did a clean the project with no improvement. I also rebooted my PC and did an explicit close of the project. There's nothing obviously wrong with the graphics.xml file - it exists in the same folder with all my other XML files; it's not write-protected or hidden. Eclipse doesn't flag any errors or warnings for it.
Thanks in advance.
I got the answer to this on the android-developers Google groups, where I also posted this question. The insightful programmer was "Bob Smith", just to give credit credit where it's due.
My bug was that the resource it was seeking was not in the correct res folder. My app runs in landscape mode on a tablet. In the manifest everything is constrained to run that way (in fact in the code it's constrained to run on one particular tablet that the company ships with their product). All the resource and layout files live in layout-land. Bob didn't know any of this but he asked the key question: were my resource files really in the right res folder?
You can do : Project > Clean and REFRESH

Android - SPAN_EXCLUSIVE_EXCLUSIVE spans cannot have a zero length

I have the following layout (virtually empty):
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/set_layout"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:contentDescription="content desc"
android:orientation="vertical" >
<TextView android:id="#+id/text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Hello, I am a TextView" />
</LinearLayout>
The Activity class contains the following:
public class TestActivity extends Activity {
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_test);
}
}
When I run this on my mobile device I get the following error:
SpannableStringBuilder
SPAN_EXCLUSIVE_EXCLUSIVE spans cannot have a zero length
I have tried this with and without the TextView and the error still remains, I must be doing something fundamentally wrong for such a basic layout to cause this.
Does anyone have any ideas on how I can get this to load without the error?
I have run into the same error entries in LogCat. In my case it's caused by the 3rd party keyboard I am using. When I change it back to Android keyboard, the error entry does not show up any more.
Because the error you're getting is not related to an EditText, then it's not related to your keyboard.
The errors you are getting are not a result of your code; you probably are testing on a Samsung device that has Samsung's TouchWiz.
I had the same errors, then I tested on a Nexus S (also by Samsung, but pure Android OS without TouchWiz) and I didn't get this error.
So, in your case, just ignore these errors while testing on a device! :)
Looking at your code, I'm not sure why you're getting that error, but I had this same error but with EditText fields.
Changing android:inputType="text" (or any of the other inputType text variations) to android:inputType="textNoSuggestions" (or android:inputType="textEmailAddress|textNoSuggestions", for example) fixed it for me.
You can also set this in Code with something like
mInputField.setInputType(InputType.TYPE_CLASS_TEXT | InputType.TYPE_TEXT_FLAG_NO_SUGGESTIONS);
Looks like Android assumes by default that EditText fields will have suggestions. When they don't, it errors. Not 100% confident in that explanation, but the above mentioned changes fixed it for me.
http://developer.android.com/reference/android/text/Spanned.html#SPAN_EXCLUSIVE_EXCLUSIVE
Hope this helps!
On your android phone go to:
settings -> application manager -> all -> samsung keyboard and then click on "clear cache"
(delete all data collected by this application).
Try using the default Android keyboard it will disappear
Make clear you have pass a value in your MainAcitivity for the following methods onCreateOptionsMenu and onCreate
In some cases, the developer deletes the "return super.onCreateOptionsMenu(menu)" statement and changed to "return true".
This worked for me...on every device
<EditText
android:maxLines="1"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:textSize="15sp"
android:layout_centerVertical="true"
android:textColor="#000"
android:id="#+id/input_search"
android:background="#null"
android:inputType="text"
android:hint="Enter Address, City or Zip Code"
android:imeOptions="actionSearch"
/>
In Java code:
mSearchText.setOnEditorActionListener(new TextView.OnEditorActionListener() {
#Override
public boolean onEditorAction(TextView textView, int actionId, KeyEvent keyEvent) {
if(actionId == EditorInfo.IME_ACTION_SEARCH
|| actionId == EditorInfo.IME_ACTION_DONE
|| keyEvent.getAction() == KeyEvent.ACTION_DOWN
|| keyEvent.getAction() == KeyEvent.KEYCODE_ENTER){
//execute our method for searching
}
return false;
}
});
I had the same warning and found that removing an unused #id got rid of the warning. For me it was obvious as the #id was associated with a growing list of textViews linked to a database, so there was a warning for each entry.
Masood Moshref is right, this error occur because the option menu of Menu is not well prepared by lacking "return super.onCreateOptionsMenu(menu)" in onCreate() method.
To try to debug this error, first go to your android terminal / console and execute this command:
ps | grep THE_ERROR_PID_YOU_GET_(IT_IS_A_NUMBER)
then if the output comes out as your app... it is your app causing the error. Try to look for empty Strings that you pass into the layout.
I had this exact same problem and it was my fault as I was passing an empty String into my layout. After changing the "" to " " this error went away.
If you don't get your app from the console output, then it is something else causing it (probably, as others said, the android keyboard)
I have faced the same issue. I almost wasted almost couple of weeks to resolved this issue.
Finally I had on doubt on myself and tried to create another project by copy and paste some startup files like SplashScreen & LoginScreen.
But with the same code still i was getting SPAN_EXCLUSIVE_EXCLUSIVE.
Then i have removed the handler code from splash screen and tried again and Wow its working.
I am not getting SPAN_EXCLUSIVE_EXCLUSIVE issue in logcat.
I wondering, why it is? till the time did not get any other solution but by removing handler from splash screen it is working.
Try and update here if it is resolved or not.
Check if you have any element such as button or text view duplicated (copied twice) in the screen where this encounters. I did this unnoticed and had to face the same issue.
I ran into this problem too when I copied some text from the Internet. My solution is to trim the text/remove formatting before doing any further processing.
I had the same problem but with a listView.... i solved it because i was using a wrong R.id.listView that list View needed to have a value, in my case it was strings that i saved on listView2... so the right code was R.id.listView2
I had the same problem then i fixed it by following code!
text = (EditText)findViewById(R.id.TextVoiceeditText);
text.setInputType(InputType.TYPE_CLASS_TEXT|InputType.TYPE_TEXT_FLAG_NO_SUGGESTIONS);
this error also occurs due to changed API URL. try hitting the URL you are using in postman and c if it's working properly.
rechecking the APIs solved my problem
try avoiding use of view in xml design.I too had the same probem but when I removed the view. its worked perfectly.
like example:
<EditText
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="Username"
android:inputType="number"
android:textColor="#fff" />
<view
android:layout_width="match_parent"
android:layout_height="1dp"
android:background="#f9d7db" />
also check and try changing by trial and error android:inputType="number" to android:inputType="text" or better not using it if not required .Sometimes keyboard stuck and gets error in some of the devices.
In my case, the EditText fields with inputType as text / textCapCharacters were casing this error. I noticed this in my logcat whenever I used backspace to completely remove the text typed in any of these fields.
The solution which worked for me was to change the inputType of those fields to textNoSuggestions as this was the most suited type and didn't give me any unwanted errors anymore.
in my case i click on recent apps shortcut on my cell phone and close all apps. This solution always work for me, because this error not related to code.
**DONT PUT SET TEXT IN TEXT WATCHER**etSearch.addTextChangedListener(object : TextWatcher {
override fun afterTextChanged(s: Editable) {
visibleResultList = false
if (s.toString().length != 0) {
getSearchSuggetion(no_of_rec, 0, s.toString())
} else {
// etSearch.setText("")
}
Log.e("text_change","============"+s.toString())
}
override fun beforeTextChanged(s: CharSequence, start: Int, count: Int, after: Int) {}
override fun onTextChanged(s: CharSequence, start: Int, before: Int, count: Int) {
}
})
To solve this problem just add android:usesCleartextTraffic="true" in your AndroidManifest.xml file which is at ..\app\src\main\AndroidManifest.xml just like bellow...

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