问题
I have three EditText widgets in my view layout. Is there a way to use a single TextWatcher for all three EditTexts?
回答1:
I just encountered this problem. I solved it by creating an inner class implementation of TextWatcher that takes a View as an argument. Then, in the method implementation, just switch on the view to see which one the Editable is coming from
Declaration:
private class GenericTextWatcher implements TextWatcher{
private View view;
private GenericTextWatcher(View view) {
this.view = view;
}
public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {}
public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {}
public void afterTextChanged(Editable editable) {
String text = editable.toString();
switch(view.getId()){
case R.id.name:
model.setName(text);
break;
case R.id.email:
model.setEmail(text);
break;
case R.id.phone:
model.setPhone(text);
break;
}
}
}
Usage:
name = (EditText) findViewById(R.id.name);
name.setText(model.getName());
name.addTextChangedListener(new GenericTextWatcher(name));
email = (EditText) findViewById(R.id.email);
email.setText(model.getEmail());
email.addTextChangedListener(new GenericTextWatcher(email));
phone = (EditText) findViewById(R.id.phone);
phone.setText(model.getPhone());
phone.addTextChangedListener(new GenericTextWatcher(phone));
回答2:
If you want to use only afterTextChanged compare editables:
@Override
public void afterTextChanged(Editable editable) {
if (editable == mEditText1.getEditableText()) {
// DO STH
} else if (editable == mEditText2.getEditableText()) {
// DO STH
}
}
回答3:
It will work with this code
TextWatcher watcher = new TextWatcher() {
@Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
//YOUR CODE
}
@Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
//YOUR CODE
}
@Override
public void afterTextChanged(Editable s) {
String outputedText = s.toString();
mOutputText.setText(outputedText);
}
};
Then add this in oncreate
mInputText.addTextChangedListener(watcher);
e2.addTextChangedListener(watcher);
e3.addTextChangedListener(watcher);
e4.addTextChangedListener(watcher);
回答4:
MultiTextWatcher Implementation
public class MultiTextWatcher {
private TextWatcherWithInstance callback;
public MultiTextWatcher setCallback(TextWatcherWithInstance callback) {
this.callback = callback;
return this;
}
public MultiTextWatcher registerEditText(final EditText editText) {
editText.addTextChangedListener(new TextWatcher() {
@Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
callback.beforeTextChanged(editText, s, start, count, after);
}
@Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
callback.onTextChanged(editText, s, start, before, count);
}
@Override
public void afterTextChanged(Editable editable) {
callback.afterTextChanged(editText, editable);
}
});
return this;
}
interface TextWatcherWithInstance {
void beforeTextChanged(EditText editText, CharSequence s, int start, int count, int after);
void onTextChanged(EditText editText, CharSequence s, int start, int before, int count);
void afterTextChanged(EditText editText, Editable editable);
}
}
Usage
new MultiTextWatcher()
.registerEditText(editText1)
.registerEditText(editText2)
.registerEditText(editText3)
.setCallback(new TextWatcherWithInstance() {
@Override
public void beforeTextChanged(EditText editText, CharSequence s, int start, int count, int after) {
// TODO: Do some thing with editText
}
@Override
public void onTextChanged(EditText editText, CharSequence s, int start, int before, int count) {
// TODO: Do some thing with editText
}
@Override
public void afterTextChanged(EditText editText, Editable editable) {
// TODO: Do some thing with editText
}
});
回答5:
If you want to use onTextChanged compare hashCode() mentioned below -
@Override
public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {
if(charSequence.hashCode() == first_edit_text.getText().hashCode()){
// do other things
}
if(charSequence.hashCode() == second_edit_text.getText().hashCode()){
// do other things
}
}
Or
If you want to use afterTextChanged compare Editable mentioned below -
@Override
public void afterTextChanged(Editable editable) {
if (editable == first_edit_text.getEditableText()) {
// do other things
} else if (editable == second_edit_text.getEditableText()) {
// do other things
}
}
回答6:
I know this is an old issue, and there is the right decision. I will write their own, maybe it will help someone.
Emulating the classic example where we have N EditText, and we want to show the button if all the fields are filled. This example makes sense, especially if further use validators for each one.
I made an example with respect to the issue, but you can do any set
MultiEditText.class
public class MultiEditText extends AppCompatActivity{
EditText ed_1, ed_2, ed_3;
Button btn_ok;
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.multi_edit_text);
ed_1 = (EditText) findViewById(R.id.ed_1);
ed_2 = (EditText) findViewById(R.id.ed_2);
ed_3 = (EditText) findViewById(R.id.ed_3);
btn_ok = (Button) findViewById(R.id.btn_ok);
btn_ok.setEnabled(false);
//if want more here can cycle interface List
EditText[] edList = {ed_1, ed_2, ed_3};
CustomTextWatcher textWatcher = new CustomTextWatcher(edList, btn_ok);
for (EditText editText : edList) editText.addTextChangedListener(textWatcher);
}
}
It looks very simple, now
CustomTextWatcher.class
public class CustomTextWatcher implements TextWatcher {
View v;
EditText[] edList;
public CustomTextWatcher(EditText[] edList, Button v) {
this.v = v;
this.edList = edList;
}
@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) {
for (EditText editText : edList) {
if (editText.getText().toString().trim().length() <= 0) {
v.setEnabled(false);
break;
}
else v.setEnabled(true);
}
}
}
I'll add a layout, so you do not waste time
multi_edit_text.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:padding="16dp">
<EditText
android:id="@+id/ed_1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="8dp" />
<EditText
android:id="@+id/ed_2"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="@+id/ed_1"
android:layout_centerHorizontal="true"
android:layout_marginTop="8dp" />
<EditText
android:id="@+id/ed_3"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="@+id/ed_2"
android:layout_centerHorizontal="true"
android:layout_marginTop="8dp" />
<Button
android:id="@+id/btn_ok"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/ed_3"
android:layout_centerHorizontal="true"
android:layout_marginTop="8dp"
android:text="OK" />
</RelativeLayout>
回答7:
Have your class inherit from Activity and implement TextWatcher.
Then through the magic of polymorphism, you just need to subscribe to the events.
This won't tell you what TextEdit changed, however using a combination of this and Sky Kelsey's answer you could sort that out nicely.
public YourActivity extends Activity implements TextWatcher {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_YourActivity);
//Subscribe to the events
EditText txt1 = (EditText) findViewById(R.id.txt1);
txt1.addTextChangedListener(this);
EditText txt2 = (EditText) findViewById(R.id.txt2);
txt2.addTextChangedListener(this);
}
@Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
EditText txt1 = (EditText) findViewById(R.id.txt1);
EditText txt2 = (EditText) findViewById(R.id.txt2);
// You probably only want the text value from the EditText. But you get the idea.
doStuff(txt1,txt2);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.calc, menu);
return true;
}
@Override
public void afterTextChanged(Editable s) {
// TODO Auto-generated method stub
}
@Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
// TODO Auto-generated method stub
}
}
回答8:
TextWatcher watcher = new TextWatcher(){
@Override
public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {
}
@Override
public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {
}
@Override
public void afterTextChanged(Editable editable) {
}
};
Then:
editText1.addTextChangedListener(watcher);
editText2.addTextChangedListener(watcher);
editText3.addTextChangedListener(watcher);
回答9:
public class MainActivity extends AppCompatActivity{
EditText value1, value2;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//instantiate EditText controls
value1 = (EditText)findViewById(R.id.txtValue1);
value2 = (EditText)findViewById(R.id.txtValue2);
//set up text changed listener
value1.addTextChangedListener(new TextChange(value1));
value2.addTextChangedListener(new TextChange(value2));
//inner class
private class TextChange implements TextWatcher {
View view;
private TextChange (View v) {
view = v;
}
@Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
}
@Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
switch (view.getId()) {
case R.id.txtValue1:
//insert your TextChangedListener codes here
break;
case R.id.txtValue2:
//insert your TextChangedListener codes here
break;
}
}
}
}
}
回答10:
Here is how I did it:
Create an ArrayList of EditTexts, and then use a for loop to apply the TextWatcher for all EditTexts, if you have one behavior for all editTexts, then just apply it there, if you specific behaviors for some specific editTexts, then u can use an if statement to select and apply to individual editTexts.
Here is my code:
ArrayList<EditText> editTexts = new ArrayList<>(); // Container list
editText1 = (EditText) findViewById(R.id.editText1);
editText2 = (EditText) findViewById(R.id.editText2);
editText3 = (EditText) findViewById(R.id.editText3);
editTexts.add(editText1); // editTexts[0]
editTexts.add(editText2); // editTexts[1]
editTexts.add(editText3); // editTexts[2]
for (final EditText editText : editTexts) { //need to be final for custom behaviors
editText.addTextChangedListener(new 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) {
}
@Override
public void afterTextChanged(Editable s) {
//Apply general behavior for all editTexts
if (editText == editTexts.get(1)) {
//Apply custom behavior just for this editText
}
}
});
}
Hope this helps
回答11:
I know this question is old, however I wanted to share one of my solution (in Kotlin). My solution is an improvement of @Shwarz Andrei's answer, my reason was what if you wanted to manipulate more things/object.
Instead of passing both list of EditTexts and a Button as params, you'd only pass your list of editText. Then within you custom class you'd implement a lambda such:
var hasFilled:((Boolean)->Unit)? = null
Then you will set or raise it inside the afterTextChanged
override fun afterTextChanged(p0: Editable?) {
for (edit in _editTextList) {
if (edit?.text.toString().trim().isEmpty()) {
hasFilled?.invoke(false) //<-- here
break
} else {
hasFilled?.invoke(true) //<--- here
}
}
}
So every time, there is a change in some EditText your lambda gets invoked
val editTexts = listOf(emailEditText,passwordEditText) // your list of editText
val textWatcher = customTextWatcher(editTexts) // initialize your custom object
editTexts.forEach { it -> it?.addTextChangedListener(textWatcher) } // each editText would listen for changes
textWatcher.hasFilled = { value -> // now you have access to your lambda
if (value != true) {
// change the state of the button to unable
// do other things
} else {
// change the state of the button to enable
// do other things
}
}
回答12:
This is my solution for kotlin. You can simply use Referential equality (===) to check same object and it's working perfectly.
val mTextWatcher = object : TextWatcher {
override fun afterTextChanged(et: Editable?) {
when {
et === et1.editableText -> {
Toast.makeText(this@MainActivity, "EditText 1", Toast.LENGTH_LONG).show()
}
et === et2.editableText -> {
Toast.makeText(this@MainActivity, "EditText 2", Toast.LENGTH_LONG).show()
}
}
}
override fun beforeTextChanged(p0: CharSequence?, p1: Int, p2: Int, p3: Int) {
}
override fun onTextChanged(p0: CharSequence?, p1: Int, p2: Int, p3: Int) {
}
}
et1.addTextChangedListener(mTextWatcher)
et2.addTextChangedListener(mTextWatcher)
来源：https://stackoverflow.com/questions/5702771/how-to-use-single-textwatcher-for-multiple-edittexts