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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