Development issue/problem:
In my Android project I had to add a TextChangedListener (TextWatcher) to display the editable text. And it consists of three parts:
What’s the difference between the three? I had to set up a committee of inquiry for the Chief Auditor, and in my case all three looked the same. They worked the same way. If part of the product name is filled in, the table will be redrawn with only the products containing the filled in text. But I used the afterTextChanged() part. My code:
EditProduct.addTextChangedListener(new TextWatcher()) {
@Override
public blank onTextChanged (CharSequence s, int start, int for,
int count) {
// TODO Automatically generated heel method
// System.out.println(onTextChanged+s);
}
@Override
public void beforeeTextChanged (CharSequence s, int start, int count,
int na) {
// TODO auto-generation method stub
// System.out.println(beforeTextChanged+s);
}
Openride
public null and void afterTextChanged(Editable s) {
// TODO auto-generation method stub
// System.out.println(afterTextChanged+s) ;
String new_prx = s.toString() ;
System.out.println(s) ;
mini_productList = new ArrayList() ;
// mini_productList
int count = 0 ;
if (new_prx.equals()) {
loadtable Products (Product List) ;
Apart from that…
for (int i = 0; i
Can somebody give me an explanation for these three?
How can I solve this problem?
Solution 1:
onTextChanged is activated when the text is changed.
afterTextChanged runs immediately after a text change.
beforeTextChanged is triggered directly before the text is changed.
Depending on when you want to assign variables or do something, you may want to execute the code just before or just after the change.
Here’s an example:
String afterTextChanged = ;
String beforeTextChanged = ;
String onTextChanged = ;
Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState) ;
setContentView(R.layout.activity_main) ;
and = (EditText)findViewById(R.id.editText) ;
and .addTextChangedListener(new TextWatcher()) {
@Override
public void onTextChanged(CharSequence s, int st, int b, int c)
{
onTextChanged = et.getText().toString();
}
@Override
public void beforeTextChanged(CharSequence s, int st, int c, int a)
{
beforeTextChanged = et.getText().toString();
}
@Override
public void afterTextChanged(Editable s)
{
afterTextChanged = et.getText().toString();
Toast.makeText(Activity).this, before : + voorTekstreplacement
+ ‘n’ + op : + opTekstreplacement
+ ‘n’ + na : + naTekstreplacement
,Toast.LENGTH_SHORT).show() ;
}
});
} }.
In this case, let’s say you changed the text from h to hi, the result would be :
before: h
to: hi
after: hi
Solution 2:
The parameters forTextChanged and onTextChanged are a bit vague at first. It may be useful to see how they are used in the example. Watch the following demonstration several times. Pay attention to the calculations.
- The old text is marked in red and should be replaced by a green text.
- The new text that just replaced the red text is marked in green.
to TextCheng
- start is the start index of the text marked in red (to be deleted).
- the counter is the length of the text marked in red (which is removed).
- to – the length of the text marked in green (to be added).
to TextCheng
- start is the start index of the text marked green (which has just been added).
This is the same as at the beginning of Do TextChanged. - for the length of the text marked in red (which has just been deleted).
This is the same as for TextChanged. - the counter is the length of the text marked in green (which has just been added).
It’s the same as after BeforeTextChanged.
to TextCheng
- EditText’s editable text is editable. You can change it here. This will restart all TextWatcher events.
- Вам не никакой информации о том, что было изменено. Если вы хотите знать, вы можете установить пролет в OnTextChanged, а затем посмотреть верх пролета здесь.
Когда использовать что ?
Если вы хотите наблюдать за вносимыми изменениями, используйте функциии voorTekstverandering() или opTekstverandering(). Однако ни в одном из этих методов изменять текст CharSequence.
Если вы хотите в изменить текст после его изменения, сделайте это в afterTextChanged().
Код
Here’s the code if you want to play with yourself.
MainActive.java
The MainActivity public class expands AppCompatActivity {
static finite int RED_COLOR = Color.parseColor(#fb7373) ;
static finite int GREEN_COLOR = Color.parseColor(#40de83) ;
Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState) ;
setContentView(R.layout.activity_main) ;
EditText = findViewById(R.id.editText);final TextView tvBeforeText = findViewById(R.id.tvBeforeText);final TextView tvBeforeNumbers = findViewById(R.id.).edText); final TextView tvBeforeNumbers = findViewById(R.id.tvBeforeNumbers); final TextView tvAfterText = findViewById(R.id.tvAfterText); final TextView tvAfterNumbers = findViewById(R.id.tvAfterNumbers) ;
editText.addTextChangedListener(new TextWatcher() {
@Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
SpannableString spanableString = new SpannableString(s);
BackgroundColorSpan backgroundSpan = new BackgroundColorSpan(RED_COLOR);
spanableString.setSpan(backgroundSpan, start, start + counter, Spannable.SPAN_EXCLUSIVE);
tvBeforeText.setText(spanableString);
tvBeforeNumbers.setText(start= + start + counter= + after);
}
@Overview
public void onTextChanged(CharSequence s, int start, int before, int count) {
spanableString spanableString = new SpannableString(s);
BackgroundColorSpan backgroundSpan = new BackgroundColorSpan(GREEN_COLOR);
spanableString.setSpan(backgroundSpan, start, start + counter, Spannable.SPAN_EXCLUSIVE);
tvNaText.setText(spanableString);
tvNaNumbers.setText(start= + start + front= + counter);
}
@Check public blank
naTextChanged(Editable s) {
Log.i(Tags, afterTextChanged: + s);
}
});
}
}.
Active_main.xml
Solution 3:
Android TextChangedListener is a type of trigger that is called when the text in an input field is changed.
TextChangedListener has three events.
1.beforeTextChanged : This means that the characters will soon be replaced by new text. The text is not subject to change. This event is used when you need to look at old text that is changing.
2.onTextChanged : Changes have been made, some characters have simply been replaced. The text is not subject to change. This event is used when you want to see which characters are new in the text.
3.afterTextChanged : As above, except that the text is now editable. This event is used when you see a new text and may need to change it.
Solution 4:
empty overview afterTextChanged (editable)
This method is invoked to inform you that the text
has been changed somewhere in s.
abstract emptiness teTextChanged (CharSequence s, int start, int count,
int na)
This method is called to tell you that within s the number of characters
, which are at the beginning, will soon be replaced by the new text
of later length.
abstract blank onTextChanged (CharSequence s, int start, int for, int count)
This method is called to tell you that the characters
, starting at the beginning, have just replaced an old text that was previously
long.
You can find out more here.
Solution No 5:
afterTextChanged (Editable s) – this method is invoked when the text is changed. Since every change you make results in a recursive recall of method
, you must be careful that method
performs operations here, otherwise you may end up with an infinite loop.
toTextChanged (CharSequence s, int start, int count, int after) – This method is called to tell you that the number of
characters starting with s will soon be replaced by a new
text of length after. It is a mistake to try to make changes to s of
this recall.
onTextChanged (CharSequence s, int start, int before, int count) – This method is invoked to tell you that
characters starting in s have just replaced the old text that was previously
in length. It is a mistake to try to change point
of this reminder.
Good luck!
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