EditText监听方法，实时的判断输入多少字符

最近在写一个小项目，其中有一点用到了显示edittext中输入了多少个字符，像微博中显示剩余多少字符的功能。在edittext提供了一个方法addtextchangedlistener实现对输入文本的监控。下边是我自己写的一个demo。

代码实现：

布局文件main.xml

[html] view plain copy
<?xml version="1.0" encoding="utf-8"?> 
<linearlayout xmlns:android="http://schemas.android.com/apk/res/android" 
 android:orientation="vertical" 
 android:layout_width="fill_parent" 
 android:layout_height="fill_parent" 
 > 
<textview android:id="@+id/tv" 
 android:layout_width="fill_parent" 
 android:layout_height="wrap_content" 
 android:textcolor="@android:color/white" 
 android:text="please input the text:" 
 /> 
<edittext android:id="@+id/et" 
 android:layout_width="match_parent" 
 android:layout_height="wrap_content" 
 /> 
</linearlayout> 

activity

[java] view plain copy
package com.damai.test; 
import android.app.activity; 
import android.os.bundle; 
import android.text.editable; 
import android.text.textwatcher; 
import android.widget.edittext; 
import android.widget.textview; 
import android.widget.toast; 
public class testactivity extends activity { 
 private textview mtextview; 
 private edittext medittext; 
 @override 
 public void oncreate(bundle savedinstancestate) { 
  super.oncreate(savedinstancestate); 
  setcontentview(r.layout.main); 
  mtextview = (textview)findviewbyid(r.id.tv); 
  medittext = (edittext)findviewbyid(r.id.et); 
  medittext.addtextchangedlistener(mtextwatcher); 
 } 
 textwatcher mtextwatcher = new textwatcher() { 
  private charsequence temp; 
  private int editstart ; 
  private int editend ; 
  @override 
  public void ontextchanged(charsequence s, int start, int before, int count) { 
   // todo auto-generated method stub 
    temp = s; 
  } 
  @override 
  public void beforetextchanged(charsequence s, int start, int count, 
    int after) { 
   // todo auto-generated method stub 
//   mtextview.settext(s);//将输入的内容实时显示 
  } 
  @override 
  public void aftertextchanged(editable s) { 
   // todo auto-generated method stub 
   editstart = medittext.getselectionstart(); 
   editend = medittext.getselectionend(); 
   mtextview.settext("您输入了" + temp.length() + "个字符"); 
   if (temp.length() > 10) { 
    toast.maketext(testactivity.this, 
      "你输入的字数已经超过了限制！", toast.length_short) 
      .show(); 
    s.delete(editstart-1, editend); 
    int tempselection = editstart; 
    medittext.settext(s); 
    medittext.setselection(tempselection); 
   } 
  } 
 }; 
} 

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