說明：

案例要時刻顯示EditText輸入多少個字元，來挺行使用者實際輸入多少個字元，和還能輸入幾個字元。

程式碼：

xml：

    <?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:

    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);//將輸入的內容實時顯示  
            }  
              
            @Override  
            public void afterTextChanged(Editable s) {  
                // TODO Auto-generated method stub  
                editStart = mEditText.getSelectionStart();  
                editEnd = mEditText.getSelectionEnd();  
                mTextView.setText("您輸入了" + temp.length() + "個字元");  
                if (temp.length() > 10) {  
                    Toast.makeText(TestActivity.this,  
                            "你輸入的字數已經超過了限制！", Toast.LENGTH_SHORT)  
                            .show();  
                    s.delete(editStart-1, editEnd);  
                    int tempSelection = editStart;  
                    mEditText.setText(s);  
                    mEditText.setSelection(tempSelection);  
                }  
            }  
        };  
    }