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);
  }
 }
};
}

来源：http://blog.csdn.net/walker02/article/details/7234458