"Android Advanced Learning" monitor edittext changes

Before the blog on the article about EditText, just introduce some of EditText's most basic usage, this time to learn more about EditText.

Monitor the change of EditText

EditText is monitored using EditText's addtextchangedlistener (Textwatcher Watcher) method, Textwatcher is an interface class, So the abstract method in Textwatcher must be implemented:

When the content inside the edittext changes, the Textchangedlistener event is triggered and the abstract method inside the Textwatcher is invoked.

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Mainactivity.java

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1 Package Com.lingdududu.watcher; 2      3 import android.app.Activity; 4 import Android.app.AlertDialog; 5 import Android.content.DialogInterface; 6 import Android.os.Bundle; 7 import android.text.Editable; 8 import Android.text.TextWatcher; 9 import Android.util.Log; Ten import Android.widget.EditText;  One       A Public class Mainactivity extends Activity { - private EditText text;  - String str;  the @Override -PublicvoidonCreate (Bundle savedinstancestate) { - super.oncreate (savedinstancestate);  - Setcontentview (R.layout.main);  +                -Text =(EditText) Findviewbyid (R.id.text);  + Text.addtextchangedlistener (Textwatcher);  A         }   at            -Private Textwatcher Textwatcher =NewTextwatcher () { -                - @Override -Publicvoidaftertextchanged (Editable s) { -                 //TODO auto-generated Method Stub inLOG.D ("TAG", "Aftertextchanged--------------->");  -             }    to                + @Override -PublicvoidBeforetextchanged (Charsequence S,intStartintCount, the                     intAfter ) {   *                 //TODO auto-generated Method Stub $LOG.D ("TAG", "Beforetextchanged--------------->"); Panax Notoginseng             }   -       the @Override +PublicvoidOnTextChanged (Charsequence S,intStartintbefore, A                     intcount) {      theLOG.D ("TAG", "OnTextChanged--------------->");  +str =Text.gettext (). toString ();  -                 Try {   $                     //if ((Heightext.gettext (). toString ())!=null) $ integer.parseint (str);  -                        -}Catch(Exception e) { the                     //Todo:handle Exception - ShowDialog (); Wuyi                 }   the                                    -             }                     Wu         };  -       AboutPrivatevoidShowDialog () { $ Alertdialog Dialog;  -Alertdialog.builder Builder =NewAlertdialog.builder (mainactivity. This);  -Builder.settitle ("Message"). SetIcon (Android.  R.DRAWABLE.STAT_NOTIFY_ERROR);  -Builder.setmessage ("The integer number you output is wrong, please correct");  ABuilder.setpositivebutton ("OK",NewDialoginterface.onclicklistener () { + @Override thePublicvoidOnClick (Dialoginterface Dialog,intwhich) {   -                     //TODO auto-generated Method Stub $                        the                 }                      the             });  theDialog =builder.create ();  the dialog.show ();  -         }   in}

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Main.xml

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1<?xml version= "1.0" encoding= "Utf-8"?>2<linearlayout xmlns:android= "Http://schemas.android.com/apk/res/android"3android:orientation= "Vertical"4Android:layout_width= "Fill_parent"5android:layout_height= "Fill_parent"6>7<TextView8Android:layout_width= "Fill_parent"9android:layout_height= "Wrap_content"Tenandroid:text= "Please enter integer number" One/> A<EditText -Android:id= "@+id/text" -Android:layout_width= "Fill_parent" theandroid:layout_height= "Wrap_content" -/> -</LinearLayout>

：

When we enter the input box is not an integer number, we will immediately pop-up the input box, prompting you to correct

In Logcat view the order in which these methods are called:

Beforetextchanged-->ontextchanged-->ontextchanged

The second example implements the function of how many characters can be entered in a hint text box.

1 Package Com.lingdududu.test; 2      3 import android.app.Activity; 4 import Android.os.Bundle; 5 import android.text.Editable; 6 import Android.text.TextWatcher; 7 import Android.view.View; 8 import Android.widget.Button; 9 import Android.widget.EditText; Ten import Android.widget.TextView;  One       A Public class Mainactivity extends Activity { - private Button clearbtn;  - private EditText et;  the private TextView TV;  -FinalintMax_length = 20;  -      intRest_length =max_length;  - @Override +PublicvoidonCreate (Bundle savedinstancestate) { - super.oncreate (savedinstancestate);  + Setcontentview (R.layout.main);  ATV =(TextView) Findviewbyid (r.id.tv);  atET =(EditText) Findviewbyid (r.id.et);  -                -CLEARBTN =(Button) Findviewbyid (R.ID.BTN);  -       -Et.addtextchangedlistener (NewTextwatcher () { -                                in @Override -PublicvoidBeforetextchanged (Charsequence S,intStartintCount, to                         intAfter ) {   +Tv.settext ("can also input" +rest_length+ "words");  -                 }   the                                * @Override $Publicvoidaftertextchanged (Editable s) {Panax NotoginsengTv.settext ("can also input" +rest_length+ "words");  -                 }   the                    + @Override APublicvoidOnTextChanged (Charsequence S,intStartintBefore,intcount) {   the                     if(rest_length>0){   +Rest_length = Max_length-et.gettext (). Length ();  -                     }   $                 }              $             });  -              -Clearbtn.setonclicklistener (NewButton.onclicklistener () { the @Override -PublicvoidOnClick (View v) {WuyiEt.settext ("");  theRest_length =max_length;  -                 }   Wu             });  -         }   About}

This article is from the "It Drip" blog, please be sure to keep this source http://liangruijun.blog.51cto.com/3061169/729505

"Android Advanced Learning" monitor edittext changes