TextWatcher

Android TextWatcher-Example?

In this tutorial show  how to implement Textwatcher in android? explain below....

Textwatcher is usefull public method in android,Textwatcher is watch input text instantly then you can update data instantly. for example validate emailId, i have implement email Validation TextWatcher .

The TextWatcher  used Some Public Method.

Public Method

This mehod is called notify somewhere text has been change.it is legitimate to make further changes.

beforTextChanged()

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

this method is called to within s the count character beginning at start are about to be replace by the new text with length after

onTextChanged()

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

}

this method is called to within s the count character beginning at start  have just replace  text had length before.

content_main.xml.
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<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    

android:layout_width="fill_parent"    

android:layout_height="fill_parent"   

android:orientation="vertical"   

android:background="#ffffff"     >

<ImageView            

android:layout_width="wrap_content"            

android:layout_height="wrap_content"            

android:id="@+id/imageView"            

android:layout_gravity="center"            

android:src="@drawable/my_heder_img">

</ImageView>

    

<EditText        

android:layout_width="match_parent"        

android:layout_height="50dp"        

android:layout_margin="30dp"        

android:id="@+id/editText2"        

android:padding="10dp"        

android:background="@drawable/register_cover"        

android:layout_gravity="center_horizontal" />


</LinearLayout>

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ActivityMain.java
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import android.app.Activity;
import android.os.Bundle;
import android.text.Editable;
import android.text.TextWatcher;
import android.widget.EditText;

public class MainActivity extends Activity  {
    String EMAIL_PATTERN = "^[_A-Za-z0-9-]+(\\.[_A-Za-z0-9-]+)*@[A-Za-z0-9]+(\\.[A-Za-z0-9]+)*(\\.[A-Za-z]{2,})$";
    EditText edittextEmailId;
 @Override    

public void onCreate(Bundle bundle) {
super.onCreate(bundle);
setContentView(R.layout.content_main);
edittextEmailId=(EditText)findViewById(R.id.editText2);
edittextEmailId.addTextChangedListener(new TextWatcher() {
 @Override           

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

 // instantly get input text                

String email = edittextEmailId.getText().toString().trim();

 //Check Email Pattern instantly                

if (email.matches(EMAIL_PATTERN) && s.length() > 0)
                

{
                   

 edittextEmailId.setError(null);
 edittextEmailId.requestFocus();

 }
                

else                

{
  edittextEmailId.setError("Invalid email address");
  edittextEmailId.requestFocus();
                

}
            

}



@Override            

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

}

@Override            

public void afterTextChanged(Editable s) {

            }
        });



    }
}

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