blocks|key|247401|text|对于TextWatcher的使用...|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|247402|et1.addTextChangedListener(new+TextWatcher()+{
++++@Override
++++public+void+onTextChanged(CharSequence+s,+int+start,+int+before,+int+count)+{

++++++++//+TODO+Auto-generated+method+stub
++++}

++++@Override
++++public+void+beforeTextChanged(CharSequence+s,+int+start,+int+count,+int+after)+{

++++++++//+TODO+Auto-generated+method+stub
++++}

++++@Override
++++public+void+afterTextChanged(Editable+s)+{

++++++++//+TODO+Auto-generated+method+stub
++++}
});|code-block|syntax|javascript|247403|entityMap^0|2|B|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|P|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|L|$]]

For use of the <code>TextWatcher</code>...

<pre><code>et1.addTextChangedListener(new TextWatcher() {
 @Override
 public void onTextChanged(CharSequence s, int start, int before, int count) {

 // TODO Auto-generated method stub
 }

 @Override
 public void beforeTextChanged(CharSequence s, int start, int count, int after) {

 // TODO Auto-generated method stub
 }

 @Override
 public void afterTextChanged(Editable s) {

 // TODO Auto-generated method stub
 }
});
</code></pre>

blocks|key|246344|text|解决方案的一个更大的视角：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|246345|@Override
++++public+View+onCreateView(LayoutInflater+inflater,+ViewGroup+container,+Bundle+savedInstanceState)+{
++++++++View+v+=+inflater.inflate(R.layout.yourlayout,+container,+false);
++++++++View+tv+=+v.findViewById(R.id.et1);
++++++++((TextView)+tv).addTextChangedListener(new+TextWatcher()+{
++++++++++++@Override
++++++++++++public+void+onTextChanged(CharSequence+s,+int+start,+int+before,+int+count)+{
+++++++++++++++++SpannableString+contentText+=+new+SpannableString(((TextView)+tv).getText());
+++++++++++++++++String+contents+=+Html.toHtml(contentText).toString();
++++++++++++}

++++++++++++@Override
++++++++++++public+void+beforeTextChanged(CharSequence+s,+int+start,+int+count,+int+after)+{

++++++++++++++++//+TODO+Auto-generated+method+stub
++++++++++++}

++++++++++++@Override
++++++++++++public+void+afterTextChanged(Editable+s)+{

++++++++++++++++//+TODO+Auto-generated+method+stub
++++++++++++}
++++++++});
++++++++return+v;
++++}|code-block|syntax|javascript|246346|这对我来说很有效，这是我第一次这样做。|246347|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

A little bigger perspective of the solution:

<pre><code>@Override
 public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
 View v = inflater.inflate(R.layout.yourlayout, container, false);
 View tv = v.findViewById(R.id.et1);
 ((TextView) tv).addTextChangedListener(new TextWatcher() {
 @Override
 public void onTextChanged(CharSequence s, int start, int before, int count) {
 SpannableString contentText = new SpannableString(((TextView) tv).getText());
 String contents = Html.toHtml(contentText).toString();
 }

 @Override
 public void beforeTextChanged(CharSequence s, int start, int count, int after) {

 // TODO Auto-generated method stub
 }

 @Override
 public void afterTextChanged(Editable s) {

 // TODO Auto-generated method stub
 }
 });
 return v;
 }
</code></pre>

This works for me, doing it my first time.

blocks|key|2919028|text|在安卓中使用TextWatcher|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|2919029|下面是一个示例代码。尝试使用TextView的addTextChangedListener方法|CODE|2919030|addTextChangedListener(new+TextWatcher()+{

++++++++BigDecimal+previousValue;
++++++++BigDecimal+currentValue;

++++++++@Override
++++++++public+void+onTextChanged(CharSequence+s,+int+start,+int+before,+int
++++++++++++++++count)+{
++++++++++++if+(isFirstTimeChange)+{
++++++++++++++++return;
++++++++++++}
++++++++++++if+(s.toString().length()+>+0)+{
++++++++++++++++try+{
++++++++++++++++++++currentValue+=+new+BigDecimal(s.toString().replace(".",+"").replace(',',+'.'));
++++++++++++++++}+catch+(Exception+e)+{
++++++++++++++++++++currentValue+=+new+BigDecimal(0);
++++++++++++++++}
++++++++++++}
++++++++}

++++++++@Override
++++++++public+void+beforeTextChanged(CharSequence+s,+int+start,+int+count,
++++++++++++++++int+after)+{
++++++++++++if+(isFirstTimeChange)+{
++++++++++++++++return;
++++++++++++}
++++++++++++if+(s.toString().length()+>+0)+{
++++++++++++++++try+{
++++++++++++++++++++previousValue+=+new+BigDecimal(s.toString().replace(".",+"").replace(',',+'.'));
++++++++++++++++}+catch+(Exception+e)+{
++++++++++++++++++++previousValue+=+new+BigDecimal(0);
++++++++++++++++}
++++++++++++}
++++++++}

++++++++@Override
++++++++public+void+afterTextChanged(Editable+editable)+{
++++++++++++if+(isFirstTimeChange)+{
++++++++++++++++isFirstTimeChange+=+false;
++++++++++++++++return;
++++++++++++}
++++++++++++if+(currentValue+!=+null+&&+previousValue+!=+null)+{
++++++++++++++++if+((currentValue.compareTo(previousValue)+>+0))+{
++++++++++++++++++++//setBackgroundResource(R.color.devises_overview_color_green);
++++++++++++++++++++setBackgroundColor(flashOnColor);
++++++++++++++++}+else+if+((currentValue.compareTo(previousValue)+<+0))+{
++++++++++++++++++++//setBackgroundResource(R.color.devises_overview_color_red);

++++++++++++++++++++setBackgroundColor(flashOffColor);
++++++++++++++++}+else+{
++++++++++++++++++++//setBackgroundColor(textColor);
++++++++++++++++}
++++++++++++++++handler.removeCallbacks(runnable);
++++++++++++++++handler.postDelayed(runnable,+1000);
++++++++++++}
++++++++}
++++});|code-block|syntax|javascript|2919031|entityMap^0|0|3|0|N|M|0|0^^$0|@$1|2|3|4|5|6|7|P|8|@$9|Q|A|R|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|S|8|@$9|T|A|U|B|H]]|D|@]|E|$]]|$1|I|3|J|5|K|7|V|8|@]|D|@]|E|$L|M]]|$1|N|3|-4|5|6|7|W|8|@]|D|@]|E|$]]]|O|$]]

Using TextWatcher in Android

Here is a sample code. Try using <code>addTextChangedListener</code> method of TextView

<pre><code>addTextChangedListener(new TextWatcher() {

 BigDecimal previousValue;
 BigDecimal currentValue;

 @Override
 public void onTextChanged(CharSequence s, int start, int before, int
 count) {
 if (isFirstTimeChange) {
 return;
 }
 if (s.toString().length() &gt; 0) {
 try {
 currentValue = new BigDecimal(s.toString().replace(".", "").replace(',', '.'));
 } catch (Exception e) {
 currentValue = new BigDecimal(0);
 }
 }
 }

 @Override
 public void beforeTextChanged(CharSequence s, int start, int count,
 int after) {
 if (isFirstTimeChange) {
 return;
 }
 if (s.toString().length() &gt; 0) {
 try {
 previousValue = new BigDecimal(s.toString().replace(".", "").replace(',', '.'));
 } catch (Exception e) {
 previousValue = new BigDecimal(0);
 }
 }
 }

 @Override
 public void afterTextChanged(Editable editable) {
 if (isFirstTimeChange) {
 isFirstTimeChange = false;
 return;
 }
 if (currentValue != null &amp;&amp; previousValue != null) {
 if ((currentValue.compareTo(previousValue) &gt; 0)) {
 //setBackgroundResource(R.color.devises_overview_color_green);
 setBackgroundColor(flashOnColor);
 } else if ((currentValue.compareTo(previousValue) &lt; 0)) {
 //setBackgroundResource(R.color.devises_overview_color_red);

 setBackgroundColor(flashOffColor);
 } else {
 //setBackgroundColor(textColor);
 }
 handler.removeCallbacks(runnable);
 handler.postDelayed(runnable, 1000);
 }
 }
 });
</code></pre>

blocks|key|242565|text|创建自定义TextWatcher子类：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|242566|public+class+CustomWatcher+implements+TextWatcher+{

++++private+boolean+mWasEdited+=+false;

++++@Override
++++public+void+beforeTextChanged(CharSequence+s,+int+start,+int+count,+int+after)+{

++++}

++++@Override
++++public+void+onTextChanged(CharSequence+s,+int+start,+int+before,+int+count)+{

++++}

++++@Override
++++public+void+afterTextChanged(Editable+s)+{

++++++++if+(mWasEdited){

++++++++++++mWasEdited+=+false;
++++++++++++return;
++++++++}

++++++++//+get+entered+value+(if+required)
++++++++String+enteredValue++=+s.toString();

++++++++String+newValue+=+"new+value";

++++++++//+don't+get+trap+into+infinite+loop
++++++++mWasEdited+=+true;
++++++++//+just+replace+entered+value+with+whatever+you+want
++++++++s.replace(0,+s.length(),+newValue);

++++}
}|code-block|syntax|javascript|242567|为您的EditText设置侦听器：|242568|mTargetEditText.addTextChangedListener(new+CustomWatcher());|242569|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

Create custom TextWatcher subclass:

<pre><code>public class CustomWatcher implements TextWatcher {

 private boolean mWasEdited = false;

 @Override
 public void beforeTextChanged(CharSequence s, int start, int count, int after) {

 }

 @Override
 public void onTextChanged(CharSequence s, int start, int before, int count) {

 }

 @Override
 public void afterTextChanged(Editable s) {

 if (mWasEdited){

 mWasEdited = false;
 return;
 }

 // get entered value (if required)
 String enteredValue = s.toString();

 String newValue = "new value";

 // don't get trap into infinite loop
 mWasEdited = true;
 // just replace entered value with whatever you want
 s.replace(0, s.length(), newValue);

 }
}
</code></pre>

Set listener for your EditText:

<pre><code>mTargetEditText.addTextChangedListener(new CustomWatcher());
</code></pre>

blocks|key|247409|text|++++public+class+Test+extends+AppCompatActivity+{

++++EditText+firstEditText;
++++EditText+secondEditText;

++++@Override
++++protected+void+onCreate(@Nullable+Bundle+savedInstanceState)+{
++++++++super.onCreate(savedInstanceState);
++++++++setContentView(R.layout.test);
++++++++firstEditText+=+(EditText)findViewById(R.id.firstEditText);
++++++++secondEditText+=+(EditText)findViewById(R.id.secondEditText);

++++++++firstEditText.addTextChangedListener(new+EditTextListener());

++++}

++++private+class+EditTextListener+implements+TextWatcher+{

++++++++@Override
++++++++public+void+beforeTextChanged(CharSequence+s,+int+start,+int+count,+int+after)+{

++++++++}

++++++++@Override
++++++++public+void+onTextChanged(CharSequence+s,+int+start,+int+before,+int+count)+{
++++++++++++secondEditText.setText(firstEditText.getText());
++++++++}

++++++++@Override
++++++++public+void+afterTextChanged(Editable+s)+{
++++++++}
++++}
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|247410|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code> public class Test extends AppCompatActivity {

 EditText firstEditText;
 EditText secondEditText;

 @Override
 protected void onCreate(@Nullable Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.test);
 firstEditText = (EditText)findViewById(R.id.firstEditText);
 secondEditText = (EditText)findViewById(R.id.secondEditText);

 firstEditText.addTextChangedListener(new EditTextListener());

 }

 private class EditTextListener implements TextWatcher {

 @Override
 public void beforeTextChanged(CharSequence s, int start, int count, int after) {

 }

 @Override
 public void onTextChanged(CharSequence s, int start, int before, int count) {
 secondEditText.setText(firstEditText.getText());
 }

 @Override
 public void afterTextChanged(Editable s) {
 }
 }
}
</code></pre>

blocks|key|242590|text|TextWatcher接口有3个回调方法，当文本发生更改时，它们都按以下顺序调用：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|242591|beforeTextChanged(CharSequence+s,+int+start,+int+count,+int+after)|code-block|syntax|javascript|242592|242593|在之前调用更改已应用到文本。|unordered-list-item|BOLD|242594|242595|在应用任何更改之前，s参数是文本。|242596|start参数是文本中已更改部分开头的位置。|242597|count参数是自start位置以来在s序列中改变的部分的长度。|242598|after参数是新序列的长度，它将替换从start到start%2Bcount的s序列的一部分。|242599|您不能从此方法(通过使用myTextView.setText(String+newText)).+)更改+TextView中的文本|242600|onTextChanged(CharSequence+s,+int+start,+int+before,+int+count)`|242601|242602|类似于beforeTextChanged方法，但在之后调用文本更改。|242603|242604|在应用更改后，s参数用于文本。|242605|start参数与beforeTextChanged方法中的参数相同。|242606|count参数是beforeTextChanged方法中的after参数。|242607|before参数是beforeTextChanged方法中的count参数。|242608|您不能从此方法(通过使用myTextView.setText(String+newText)).+)更改+TextView中的文本|242609|afterTextChanged(Editable+s)|242610|242611|可以通过此方法更改+TextView中的文本。|242612|242613|/!\警告：当您更改TextView中的文本时，TextWatcher将再次被触发，从而开始无限循环。然后，您应该添加一个类似boolean+_ignore的属性，以防止无限循环。|242614|例如：|242615|new+TextWatcher()+{
++++++++boolean+_ignore+=+false;+//+indicates+if+the+change+was+made+by+the+TextWatcher+itself.

++++++++@Override
++++++++public+void+afterTextChanged(Editable+s)+{
++++++++++++if+(_ignore)
++++++++++++++++return;

++++++++++++_ignore+=+true;+//+prevent+infinite+loop
++++++++++++//+Change+your+text+here.
++++++++++++//+myTextView.setText(myNewText);
++++++++++++_ignore+=+false;+//+release,+so+the+TextWatcher+start+to+listen+again.
++++++++}

++++++++//+Other+methods...
}|242616|摘要：|242617|​|242618|📷|atomic|242619|242620|242621|一个可以使用的类：TextViewListener|242622|就我个人而言，我制作了自己的自定义文本侦听器，它将4个部分放在单独的字符串中，对我来说，使用起来更直观。|242623|+/**
+++*+Text+view+listener+which+splits+the+update+text+event+in+four+parts:
+++*+<ul>
+++*+++++<li>The+text+placed+before+the+updated+part.</li>
+++*+++++<li>The+old+text+in+the+updated+part.</li>
+++*+++++<li>The+new+text+in+the+updated+part.</li>
+++*+++++<li>The+text+placed+after+the+updated+part.</li>
+++*+</ul>
+++*+Created+by+Jeremy+B.
+++*/
++
++public+abstract+class+TextViewListener+implements+TextWatcher+{
++++/**
+++++*+Unchanged+sequence+which+is+placed+before+the+updated+sequence.
+++++*/
++++private+String+_before;
++
++++/**
+++++*+Updated+sequence+before+the+update.
+++++*/
++++private+String+_old;
++
++++/**
+++++*+Updated+sequence+after+the+update.
+++++*/
++++private+String+_new;
++
++++/**
+++++*+Unchanged+sequence+which+is+placed+after+the+updated+sequence.
+++++*/
++++private+String+_after;
++
++++/**
+++++*+Indicates+when+changes+are+made+from+within+the+listener,+should+be+omitted.
+++++*/
++++private+boolean+_ignore+=+false;
++
++++@Override
++++public+void+beforeTextChanged(CharSequence+sequence,+int+start,+int+count,+int+after)+{
++++++++_before+=+sequence.subSequence(0,start).toString();
++++++++_old+=+sequence.subSequence(start,+start%2Bcount).toString();
++++++++_after+=+sequence.subSequence(start%2Bcount,+sequence.length()).toString();
++++}
++
++++@Override
++++public+void+onTextChanged(CharSequence+sequence,+int+start,+int+before,+int+count)+{
++++++++_new+=+sequence.subSequence(start,+start%2Bcount).toString();
++++}
++
++++@Override
++++public+void+afterTextChanged(Editable+sequence)+{
++++++++if+(_ignore)
++++++++++++return;
++
++++++++onTextChanged(_before,+_old,+_new,+_after);
++++}
++
++++/**
+++++*+Triggered+method+when+the+text+in+the+text+view+has+changed.
+++++*+ 
+++++*+You+can+apply+changes+to+the+text+view+from+this+method
+++++*+with+the+condition+to+call+{@link+#startUpdates()}+before+any+update,
+++++*+and+to+call+{@link+#endUpdates()}+after+them.
+++++*
+++++*+@param+before+Unchanged+part+of+the+text+placed+before+the+updated+part.
+++++*+@param+old+Old+updated+part+of+the+text.
+++++*+@param+aNew+New+updated+part+of+the+text?
+++++*+@param+after+Unchanged+part+of+the+text+placed+after+the+updated+part.
+++++*/
++++protected+abstract+void+onTextChanged(String+before,+String+old,+String+aNew,+String+after);
++
++++/**
+++++*+Call+this+method+when+you+start+to+update+the+text+view,+so+it+stops+listening+to+it+and+then+prevent+an+infinite+loop.
+++++*+@see+#endUpdates()
+++++*/
++++protected+void+startUpdates(){
++++++++_ignore+=+true;
++++}
++
++++/**
+++++*+Call+this+method+when+you+finished+to+update+the+text+view+in+order+to+restart+to+listen+to+it.
+++++*+@see+#startUpdates()
+++++*/
++++protected+void+endUpdates(){
++++++++_ignore+=+false;
++++}
++}|242624|示例：|242625|myEditText.addTextChangedListener(new+TextViewListener()+{
++++++++@Override
++++++++protected+void+onTextChanged(String+before,+String+old,+String+aNew,+String+after)+{
+++++++++++//+intuitive+use+of+parameters
+++++++++++String+completeOldText+=+before+%2B+old+%2B+after;
+++++++++++String+completeNewText+=+before+%2B+aNew+%2B+after;
+++++++++++
+++++++++++//+update+TextView
++++++++++++startUpdates();+//+to+prevent+infinite+loop.
++++++++++++myEditText.setText(myNewText);
++++++++++++endUpdates();
++++++++}
}|242626|entityMap|0|IMAGE|mutability|IMMUTABLE|imageUrl|https://ask.qcloudimg.com/http-save/yehe-900000/999b67eab1f383992b2db024e516f1ad.png|imageAlt^0|0|B|0|0|0|5|9|0|0|0|H|A|1|0|0|M|0|5|0|0|W|0|5|9|5|J|1|0|0|B|C|Y|0|5|K|5|Q|B|12|1|0|0|1G|1H|C|C|Y|1H|8|0|0|0|0|P|T|5|3|H|0|0|0|3|C|3|7|1|0|0|Y|0|5|8|H|0|0|11|0|5|T|5|0|0|12|0|6|U|5|0|0|1G|1H|C|C|Y|1H|8|0|0|0|0|9|A|D|A|8|0|0|0|2I|A|8|O|B|1R|F|0|0|3|0|0|0|3|0|0|1|0|0|1|0|1|0|0|0|1|0|0|0|P|9|G|0|0|1G|0|0|256|0|0|3|0|0|E4|0^^$0|@$1|2|3|4|5|6|7|2K|8|@$9|2L|A|2M|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|2N|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|2O|8|@]|D|@]|E|$]]|$1|L|3|M|5|N|7|2P|8|@$9|2Q|A|2R|B|O]]|D|@]|E|$]]|$1|P|3|-4|5|6|7|2S|8|@]|D|@]|E|$]]|$1|Q|3|R|5|6|7|2T|8|@$9|2U|A|2V|B|O]|$9|2W|A|2X|B|C]]|D|@]|E|$]]|$1|S|3|T|5|6|7|2Y|8|@$9|2Z|A|30|B|O]|$9|31|A|32|B|C]]|D|@]|E|$]]|$1|U|3|V|5|6|7|33|8|@$9|34|A|35|B|O]|$9|36|A|37|B|C]|$9|38|A|39|B|C]|$9|3A|A|3B|B|C]]|D|@]|E|$]]|$1|W|3|X|5|6|7|3C|8|@$9|3D|A|3E|B|O]|$9|3F|A|3G|B|O]|$9|3H|A|3I|B|C]|$9|3J|A|3K|B|C]|$9|3L|A|3M|B|C]|$9|3N|A|3O|B|C]]|D|@]|E|$]]|$1|Y|3|Z|5|6|7|3P|8|@$9|3Q|A|3R|B|O]|$9|3S|A|3T|B|O]|$9|3U|A|3V|B|C]|$9|3W|A|3X|B|C]]|D|@]|E|$]]|$1|10|3|11|5|H|7|3Y|8|@]|D|@]|E|$I|J]]|$1|12|3|-4|5|6|7|3Z|8|@]|D|@]|E|$]]|$1|13|3|14|5|N|7|40|8|@$9|41|A|42|B|O]|$9|43|A|44|B|O]|$9|45|A|46|B|C]]|D|@]|E|$]]|$1|15|3|-4|5|6|7|47|8|@]|D|@]|E|$]]|$1|16|3|17|5|6|7|48|8|@$9|49|A|4A|B|O]|$9|4B|A|4C|B|O]|$9|4D|A|4E|B|C]]|D|@]|E|$]]|$1|18|3|19|5|6|7|4F|8|@$9|4G|A|4H|B|O]|$9|4I|A|4J|B|C]|$9|4K|A|4L|B|C]]|D|@]|E|$]]|$1|1A|3|1B|5|6|7|4M|8|@$9|4N|A|4O|B|O]|$9|4P|A|4Q|B|C]|$9|4R|A|4S|B|C]]|D|@]|E|$]]|$1|1C|3|1D|5|6|7|4T|8|@$9|4U|A|4V|B|O]|$9|4W|A|4X|B|C]|$9|4Y|A|4Z|B|C]]|D|@]|E|$]]|$1|1E|3|1F|5|6|7|50|8|@$9|51|A|52|B|O]|$9|53|A|54|B|O]|$9|55|A|56|B|C]|$9|57|A|58|B|C]]|D|@]|E|$]]|$1|1G|3|1H|5|H|7|59|8|@]|D|@]|E|$I|J]]|$1|1I|3|-4|5|6|7|5A|8|@]|D|@]|E|$]]|$1|1J|3|1K|5|N|7|5B|8|@$9|5C|A|5D|B|O]|$9|5E|A|5F|B|O]|$9|5G|A|5H|B|C]]|D|@]|E|$]]|$1|1L|3|-4|5|6|7|5I|8|@]|D|@]|E|$]]|$1|1M|3|1N|5|6|7|5J|8|@$9|5K|A|5L|B|O]|$9|5M|A|5N|B|C]|$9|5O|A|5P|B|C]|$9|5Q|A|5R|B|C]]|D|@]|E|$]]|$1|1O|3|1P|5|6|7|5S|8|@$9|5T|A|5U|B|O]]|D|@]|E|$]]|$1|1Q|3|1R|5|H|7|5V|8|@]|D|@]|E|$I|J]]|$1|1S|3|1T|5|6|7|5W|8|@$9|5X|A|5Y|B|O]]|D|@]|E|$]]|$1|1U|3|1V|5|6|7|5Z|8|@$9|60|A|61|B|O]]|D|@]|E|$]]|$1|1W|3|1X|5|1Y|7|62|8|@$9|63|A|64|B|O]]|D|@$9|65|A|66|1|67]]|E|$]]|$1|1Z|3|1V|5|6|7|68|8|@$9|69|A|6A|B|O]]|D|@]|E|$]]|$1|20|3|-4|5|6|7|6B|8|@]|D|@]|E|$]]|$1|21|3|22|5|6|7|6C|8|@$9|6D|A|6E|B|O]|$9|6F|A|6G|B|C]]|D|@]|E|$]]|$1|23|3|24|5|6|7|6H|8|@$9|6I|A|6J|B|O]]|D|@]|E|$]]|$1|25|3|26|5|H|7|6K|8|@$9|6L|A|6M|B|O]]|D|@]|E|$I|J]]|$1|27|3|28|5|6|7|6N|8|@$9|6O|A|6P|B|O]]|D|@]|E|$]]|$1|29|3|2A|5|H|7|6Q|8|@$9|6R|A|6S|B|O]]|D|@]|E|$I|J]]|$1|2B|3|-4|5|6|7|6T|8|@]|D|@]|E|$]]]|2C|$2D|$5|2E|2F|2G|E|$2H|2I|2J|-4]]]]

The <code>TextWatcher</code> interface has 3 callbacks methods which are all called in the following order when a change occurred to the text:
<pre class="lang-java prettyprint-override"><code>beforeTextChanged(CharSequence s, int start, int count, int after)
</code></pre>
<ul>
<li>Called before the changes have been applied to the text. 
The <code>s</code> parameter is the text before any change is applied. 
The <code>start</code> parameter is the position of the beginning of the changed part in the text. 
The <code>count</code> parameter is the length of the changed part in the <code>s</code> sequence since the <code>start</code> position. 
And the <code>after</code> parameter is the length of the new sequence which will replace the part of the <code>s</code> sequence from <code>start</code> to <code>start+count</code>. 
You must not change the text in the <code>TextView</code> from this method (by using <code>myTextView.setText(String newText)</code>).</li>
</ul>
<pre class="lang-java prettyprint-override"><code>onTextChanged(CharSequence s, int start, int before, int count)`
</code></pre>
<ul>
<li>Similar to the <code>beforeTextChanged</code> method but called after the text changes. 
The <code>s</code> parameter is the text after changes have been applied. 
The <code>start</code> parameter is the same as in the <code>beforeTextChanged</code> method. 
The <code>count</code> parameter is the <code>after</code> parameter in the beforeTextChanged method. 
And the <code>before</code> parameter is the <code>count</code> parameter in the beforeTextChanged method. 
You must not change the text in the <code>TextView</code> from this method (by using <code>myTextView.setText(String newText)</code>).</li>
</ul>
<pre class="lang-java prettyprint-override"><code>afterTextChanged(Editable s)
</code></pre>
<ul>
<li>You can change the text in the <code>TextView</code> from this method. 
/!\ Warning: When you change the text in the <code>TextView</code>, the <code>TextWatcher</code> will be triggered again, starting an infinite loop. You should then add like a <code>boolean _ignore</code> property which prevent the infinite loop. 
Exemple:</li>
</ul>
<pre class="lang-java prettyprint-override"><code>new TextWatcher() {
 boolean _ignore = false; // indicates if the change was made by the TextWatcher itself.

 @Override
 public void afterTextChanged(Editable s) {
 if (_ignore)
 return;

 _ignore = true; // prevent infinite loop
 // Change your text here.
 // myTextView.setText(myNewText);
 _ignore = false; // release, so the TextWatcher start to listen again.
 }

 // Other methods...
}
</code></pre>
<h2>Summary:</h2>
<a href="https://i.stack.imgur.com/asxgN.png" rel="noreferrer"><img src="https://i.stack.imgur.com/asxgN.png" alt="enter image description here" /></a>
<hr />
<h2>A ready to use class: <code>TextViewListener</code></h2>
Personally, I made my custom text listener, which gives me the 4 parts in separate strings, which is, for me, much more intuitive to use.
<pre><code> /**
 * Text view listener which splits the update text event in four parts:
 * &lt;ul&gt;
 * &lt;li&gt;The text placed &lt;b&gt;before&lt;/b&gt; the updated part.&lt;/li&gt;
 * &lt;li&gt;The &lt;b&gt;old&lt;/b&gt; text in the updated part.&lt;/li&gt;
 * &lt;li&gt;The &lt;b&gt;new&lt;/b&gt; text in the updated part.&lt;/li&gt;
 * &lt;li&gt;The text placed &lt;b&gt;after&lt;/b&gt; the updated part.&lt;/li&gt;
 * &lt;/ul&gt;
 * Created by Jeremy B.
 */
 
 public abstract class TextViewListener implements TextWatcher {
 /**
 * Unchanged sequence which is placed before the updated sequence.
 */
 private String _before;
 
 /**
 * Updated sequence before the update.
 */
 private String _old;
 
 /**
 * Updated sequence after the update.
 */
 private String _new;
 
 /**
 * Unchanged sequence which is placed after the updated sequence.
 */
 private String _after;
 
 /**
 * Indicates when changes are made from within the listener, should be omitted.
 */
 private boolean _ignore = false;
 
 @Override
 public void beforeTextChanged(CharSequence sequence, int start, int count, int after) {
 _before = sequence.subSequence(0,start).toString();
 _old = sequence.subSequence(start, start+count).toString();
 _after = sequence.subSequence(start+count, sequence.length()).toString();
 }
 
 @Override
 public void onTextChanged(CharSequence sequence, int start, int before, int count) {
 _new = sequence.subSequence(start, start+count).toString();
 }
 
 @Override
 public void afterTextChanged(Editable sequence) {
 if (_ignore)
 return;
 
 onTextChanged(_before, _old, _new, _after);
 }
 
 /**
 * Triggered method when the text in the text view has changed.
 * &lt;br/&gt;
 * You can apply changes to the text view from this method
 * with the condition to call {@link #startUpdates()} before any update,
 * and to call {@link #endUpdates()} after them.
 *
 * @param before Unchanged part of the text placed before the updated part.
 * @param old Old updated part of the text.
 * @param aNew New updated part of the text?
 * @param after Unchanged part of the text placed after the updated part.
 */
 protected abstract void onTextChanged(String before, String old, String aNew, String after);
 
 /**
 * Call this method when you start to update the text view, so it stops listening to it and then prevent an infinite loop.
 * @see #endUpdates()
 */
 protected void startUpdates(){
 _ignore = true;
 }
 
 /**
 * Call this method when you finished to update the text view in order to restart to listen to it.
 * @see #startUpdates()
 */
 protected void endUpdates(){
 _ignore = false;
 }
 }
</code></pre>
Example:
<pre><code>myEditText.addTextChangedListener(new TextViewListener() {
 @Override
 protected void onTextChanged(String before, String old, String aNew, String after) {
 // intuitive use of parameters
 String completeOldText = before + old + after;
 String completeNewText = before + aNew + after;
 
 // update TextView
 startUpdates(); // to prevent infinite loop.
 myEditText.setText(myNewText);
 endUpdates();
 }
}
</code></pre>

blocks|key|3133369|text|补充答案|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3133370|这里是对其他答案的视觉补充。我对代码和解释的更完整的回答是here。|offset|length|3133371|3133372|+(replaced)|unordered-list-item|3133373|Green：：即将删除的文本刚刚添加的文本(替换旧的红色文本)|3133374|3133375|​|3133376|📷|atomic|3133377|3133378|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/a/47263021/3681880|1|IMAGE|IMMUTABLE|imageUrl|https://ask.qcloudimg.com/http-save/yehe-900000/b6abff1f17d5caf181707d1966ad93df.gif|imageAlt^0|0|T|4|0|0|0|0|0|0|0|0|1|1|0|0^^$0|@$1|2|3|4|5|6|7|16|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|17|8|@]|9|@$D|18|E|19|1|1A]]|A|$]]|$1|F|3|-4|5|6|7|1B|8|@]|9|@]|A|$]]|$1|G|3|H|5|I|7|1C|8|@]|9|@]|A|$]]|$1|J|3|K|5|I|7|1D|8|@]|9|@]|A|$]]|$1|L|3|-4|5|6|7|1E|8|@]|9|@]|A|$]]|$1|M|3|N|5|6|7|1F|8|@]|9|@]|A|$]]|$1|O|3|P|5|Q|7|1G|8|@]|9|@$D|1H|E|1I|1|1J]]|A|$]]|$1|R|3|N|5|6|7|1K|8|@]|9|@]|A|$]]|$1|S|3|-4|5|6|7|1L|8|@]|9|@]|A|$]]]|T|$U|$5|V|W|X|A|$Y|Z]]|10|$5|11|W|12|A|$13|14|15|-4]]]]

<h1>Supplemental answer</h1>
Here is a visual supplement to the other answers. My fuller answer with the code and explanations is <a href="https://stackoverflow.com/a/47263021/3681880">here</a>.
<ul>
<li>Red: text about to be deleted (replaced)</li>
<li>Green: text that was just added (replacing the old red text)</li>
</ul>
<a href="https://i.stack.imgur.com/yhv4A.gif" rel="noreferrer"><img src="https://i.stack.imgur.com/yhv4A.gif" alt="enter image description here" /></a>

blocks|key|242661|text|对于Kotlin，使用KTX扩展函数：(它使用TextWatcher作为前面的答案)|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|CODE|entityRanges|data|242662|yourEditText.doOnTextChanged+{+text,+start,+count,+after+->+
++++++++//+action+which+will+be+invoked+when+the+text+is+changing
++++}|code-block|syntax|javascript|242663|导入core-KTX|242664|implementation+"androidx.core:core-ktx:1.2.0"|242665|entityMap^0|2|6|B|5|N|B|0|0|2|8|0|0^^$0|@$1|2|3|4|5|6|7|R|8|@$9|S|A|T|B|C]|$9|U|A|V|B|C]|$9|W|A|X|B|D]]|E|@]|F|$]]|$1|G|3|H|5|I|7|Y|8|@]|E|@]|F|$J|K]]|$1|L|3|M|5|6|7|Z|8|@$9|10|A|11|B|D]]|E|@]|F|$]]|$1|N|3|O|5|I|7|12|8|@]|E|@]|F|$J|K]]|$1|P|3|-4|5|6|7|13|8|@]|E|@]|F|$]]]|Q|$]]

For Kotlin use KTX extension function:
(It uses <code>TextWatcher</code> as previous answers)

<pre><code>yourEditText.doOnTextChanged { text, start, count, after -&gt; 
 // action which will be invoked when the text is changing
 }
</code></pre>

 
import <code>core-KTX</code>:

<pre><code>implementation "androidx.core:core-ktx:1.2.0"
</code></pre>

blocks|key|2919160|text|如果使用对话框edittext实现。像这样使用：。它与其他edittext的用法相同。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2919161|dialog.getInputEditText().addTextChangedListener(new+TextWatcher()+{
++++@Override
++++public+void+beforeTextChanged(CharSequence+charSequence,+int+start,+int+before,+int+count)+{
++++}

++++@Override
++++public+void+onTextChanged(CharSequence+charSequence,+int+start,+int+before,+int+count)+{
++++++++if+(start<2){
++++++++++++++++dialog.getActionButton(DialogAction.POSITIVE).setEnabled(false);
++++++++++++}else{
++++++++++++++++double+size+=++Double.parseDouble(charSequence.toString());
++++++++++++++++if+(size+>+0.000001+&&+size+<+0.999999){
++++++++++++++++++++dialog.getActionButton(DialogAction.POSITIVE).setEnabled(true);
++++++++++++++++}else{
++++++++++++++++++++ToastHelper.show(HistoryActivity.this,+"Size+must+between+0.1+-+0.9");
++++++++++++++++++++dialog.getActionButton(DialogAction.POSITIVE).setEnabled(false);
++++++++++++++++}

++++++++++++}
++++}

++++@Override
++++public+void+afterTextChanged(Editable+editable)+{

++++}
});|code-block|syntax|javascript|2919162|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

if you implement with dialog edittext. use like this:. its same with use to other edittext.

<pre><code>dialog.getInputEditText().addTextChangedListener(new TextWatcher() {
 @Override
 public void beforeTextChanged(CharSequence charSequence, int start, int before, int count) {
 }

 @Override
 public void onTextChanged(CharSequence charSequence, int start, int before, int count) {
 if (start&lt;2){
 dialog.getActionButton(DialogAction.POSITIVE).setEnabled(false);
 }else{
 double size = Double.parseDouble(charSequence.toString());
 if (size &gt; 0.000001 &amp;&amp; size &lt; 0.999999){
 dialog.getActionButton(DialogAction.POSITIVE).setEnabled(true);
 }else{
 ToastHelper.show(HistoryActivity.this, "Size must between 0.1 - 0.9");
 dialog.getActionButton(DialogAction.POSITIVE).setEnabled(false);
 }

 }
 }

 @Override
 public void afterTextChanged(Editable editable) {

 }
});
</code></pre>

Can anyone tell me how to mask the substring in <code>EditText</code> or how to change <code>EditText</code> substring input to password type or replace by another character like this 123xxxxxxxxx3455

<pre><code> String contents = et1.getText().toString();
 et1.setText(contents.replace.substring(0, contents.length()-2),"*");
</code></pre>

Please, tell me how I can use the <code>TextWatcher</code> method in Android.

How to use the TextWatcher class in Android?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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谁能告诉我如何在EditText中屏蔽子串，或者如何将EditText 子串输入更改为密码类型或将替换为另一个字符，如123xxxxxxxxx3455 String contents = et1.getText().toString(); et1.setText(contents.replace.substring(0...

问如何在安卓系统中使用TextWatcher类？
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问如何在安卓系统中使用TextWatcher类？
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