<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:tools="http://schemas.android.com/tools"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:paddingBottom="@dimen/activity_vertical_margin"
  android:paddingLeft="@dimen/activity_horizontal_margin"
  android:paddingRight="@dimen/activity_horizontal_margin"
  android:paddingTop="@dimen/activity_vertical_margin"
  tools:context=".MainActivity" >
  <!-- 整體布局，包括增加和減少商品數(shù)量的符號(hào)以及中間的商品數(shù)量 -->
  <LinearLayout
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal">
    <!-- 減少商品數(shù)量的布局 -->
    <Button
      android:id="@+id/addbt"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:textColor="#0157D3"
      android:text="-">
    </Button>
    <!-- 商品數(shù)量的布局 -->
    <EditText
      android:id="@+id/edt"
      android:text="0"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content">
    </EditText>
    <!-- 增加商品數(shù)量的布局 -->
    <Button
      android:id="@+id/subbt"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:textColor="#0157D3"
      android:text="+">
    </Button>
    <!-- 顯示商品數(shù)量的布局 -->
    <TextView
      android:id="@+id/ttt"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content">
    </TextView>
  </LinearLayout>
</RelativeLayout>

package jczb.shoping.ui;
import android.R.string;
import android.app.Activity;
import android.os.Bundle;
import android.text.Editable;
import android.text.TextWatcher;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
public class ShoppingCartItemActivity extends Activity {
  private Button btAdd, btReduce;
  private EditText edtNumber;
  int num=0; //數(shù)量
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_shoppingcart_item);
    btAdd=(Button)findViewById(R.id.cart_pro_reduce);
    btReduce=(Button) findViewById(R.id.cart_pro_add);
    edtNumber=(EditText) findViewById(R.id.cart_pro_count);
    btAdd.setTag("+");
    btReduce.setTag("-");
    //設(shè)置輸入類(lèi)型為數(shù)字
    edtNumber.setInputType(android.text.InputType.TYPE_CLASS_NUMBER);
    edtNumber.setText(String.valueOf(num));
    SetViewListener();
  }
  /**
   * 設(shè)置文本變化相關(guān)監(jiān)聽(tīng)事件
   */
  private void SetViewListener()
  {
    btAdd.setOnClickListener(new OnButtonClickListener());
    btReduce.setOnClickListener(new OnButtonClickListener());
    edtNumber.addTextChangedListener(new OnTextChangeListener());
  }
  /**
   * 加減按鈕事件監(jiān)聽(tīng)器
   *
   *
   */
  class OnButtonClickListener implements OnClickListener
  {
    @Override
    public void onClick(View v)
    {
      String numString = edtNumber.getText().toString();
      if (numString == null || numString.equals(""))
      {
        num = 0;
        edtNumber.setText("0");
      } else
      {
        if (v.getTag().equals("-"))
        {
          if (++num < 0) //先加，再判斷
          {
            num--;
            Toast.makeText(ShoppingCartItemActivity.this, "請(qǐng)輸入一個(gè)大于0的數(shù)字",
                Toast.LENGTH_SHORT).show();
          } else
          {
            edtNumber.setText(String.valueOf(num));
          }
        } else if (v.getTag().equals("+"))
        {
          if (--num < 0) //先減，再判斷
          {
            num++;
            Toast.makeText(ShoppingCartItemActivity.this, "請(qǐng)輸入一個(gè)大于0的數(shù)字",
                Toast.LENGTH_SHORT).show();
          } else
          {
            edtNumber.setText(String.valueOf(num));
          }
        }
      }
    }
  }
  /**
   * EditText輸入變化事件監(jiān)聽(tīng)器
   */
  class OnTextChangeListener implements TextWatcher
  {
    @Override
    public void afterTextChanged(Editable s)
    {
      String numString = s.toString();
      if(numString == null || numString.equals(""))
      {
        num = 0;
      }
      else {
        int numInt = Integer.parseInt(numString);
        if (numInt < 0)
        {
          Toast.makeText(ShoppingCartItemActivity.this, "請(qǐng)輸入一個(gè)大于0的數(shù)字",
              Toast.LENGTH_SHORT).show();
        } else
        {
          //設(shè)置EditText光標(biāo)位置 為文本末端
          edtNumber.setSelection(edtNumber.getText().toString().length());
          num = numInt;
        }
      }
    }
    @Override
    public void beforeTextChanged(CharSequence s, int start, int count,
        int after)
    {
    }
    @Override
    public void onTextChanged(CharSequence s, int start, int before,
        int count)
    {
    }
  }
}