EditText监听方法，实时的判断输入多少字符

所属分类：软件编程 / Android 阅读数： 49

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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); 
   } 
  } 
 }; 
}