package com.example.calculator;import android.app.Activity;import android.os.Bundle;import android.view.Menu;import android.view.MenuItem;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.EditText;import android.widget.ImageView;import android.widget.TextView;import android.widget.Toast;public class MainActivity extends Activity implements OnClickListener {  Button b1, b2, b3, b4, b5, b6, b7, b8, b9, b0, bp, bs, bm, bd, bc, be;  ImageView delete;  TextView tv;  EditText show;  String showString = "", option = "";  int showfirst = 0;  String exception = "";  @Override  protected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_main);    b0 = (Button) findViewById(R.id.bt_0);    b1 = (Button) findViewById(R.id.bt_1);    b2 = (Button) findViewById(R.id.bt_2);    b3 = (Button) findViewById(R.id.bt_3);    b4 = (Button) findViewById(R.id.bt_4);    b5 = (Button) findViewById(R.id.bt_5);    b6 = (Button) findViewById(R.id.bt_6);    b7 = (Button) findViewById(R.id.bt_7);    b8 = (Button) findViewById(R.id.bt_8);    b9 = (Button) findViewById(R.id.bt_9);    bp = (Button) findViewById(R.id.bt_plus);    bs = (Button) findViewById(R.id.bt_sub);    bm = (Button) findViewById(R.id.bt_mutilate);    bd = (Button) findViewById(R.id.bt_div);    bc = (Button) findViewById(R.id.bt_c);    be = (Button) findViewById(R.id.bt_equ);    b1.setOnClickListener(this);    b2.setOnClickListener(this);    b3.setOnClickListener(this);    b4.setOnClickListener(this);    b5.setOnClickListener(this);    b6.setOnClickListener(this);    b7.setOnClickListener(this);    b8.setOnClickListener(this);    b9.setOnClickListener(this);    b0.setOnClickListener(this);    bp.setOnClickListener(this);    bs.setOnClickListener(this);    bm.setOnClickListener(this);    bd.setOnClickListener(this);    bc.setOnClickListener(this);    be.setOnClickListener(this);    show = (EditText) findViewById(R.id.et_show);    delete = (ImageView) findViewById(R.id.iv_delete);    delete.setOnClickListener(this);    tv=(TextView) findViewById(R.id.author);    tv.setOnClickListener(this);  }  @Override  public boolean onCreateOptionsMenu(Menu menu) {    // Inflate the menu; this adds items to the action bar if it is present.    getMenuInflater().inflate(R.menu.main, menu);    return true;  }  @Override  public boolean onOptionsItemSelected(MenuItem item) {    // Handle action bar item clicks here. The action bar will    // automatically handle clicks on the Home/Up button, so long    // as you specify a parent activity in AndroidManifest.xml.    int id = item.getItemId();    if (id == R.id.action_settings) {      return true;    }    return super.onOptionsItemSelected(item);  }  @Override  public void onClick(View v) {    switch (v.getId()) {    case R.id.bt_0:      showString += "0";      break;    case R.id.bt_1:      showString += "1";      break;    case R.id.bt_2:      showString += "2";      break;    case R.id.bt_3:      showString += "3";      break;    case R.id.bt_4:      showString += "4";      break;    case R.id.bt_5:      showString += "5";      break;    case R.id.bt_6:      showString += "6";      break;    case R.id.bt_7:      showString += "7";      break;    case R.id.bt_8:      showString += "8";      break;    case R.id.bt_9:      showString += "9";      break;    case R.id.bt_plus:      if (showString.equals(""))        exception = "先輸入數值哦";      else {        showfirst = Integer.parseInt(showString);        showString = "";        option = "+";      }      break;    case R.id.bt_sub:      if (showString.equals(""))        exception = "先輸入數值哦";      else {        showfirst = Integer.parseInt(showString);        showString = "";        option = "-";      }      break;    case R.id.bt_mutilate:      if (showString.equals(""))        exception = "先輸入數值哦";      else {        showfirst = Integer.parseInt(showString);        showString = "";        option = "*";      }      break;    case R.id.bt_div:      if (showString.equals(""))        exception = "先輸入數值哦";      else {        showfirst = Integer.parseInt(showString);        showString = "";        option = "/";      }      break;    case R.id.bt_equ:      if (option.equals("+"))        showString = showfirst + Integer.parseInt(showString) + "";      else if (option.equals("-")) {        showString = showfirst - Integer.parseInt(showString) + "";      } else if (option.equals("*")) {        showString = showfirst * Integer.parseInt(showString) + "";      } else if (option.equals("/")) {        if (showString.equals("0")) {          exception = "除數不能為0！";        } else          showString = showfirst / Integer.parseInt(showString) + "";      }      break;    case R.id.bt_c:      showString = "";      break;    case R.id.iv_delete:      Toast.makeText(MainActivity.this, showString + "已被清空",          Toast.LENGTH_SHORT).show();      showString = "";      break;    case R.id.author:      Toast.makeText(MainActivity.this, "鄭明亮/n軟件工程/nQQ：1072307340",          Toast.LENGTH_SHORT).show();      break;    default:      break;    }    if (exception.equals(""))      show.setText(showString);    else {      show.setText(exception);      exception = "";    }    // 設置文本框顏色；    if (!show.getText().toString().equals("")) {      delete.setBackgroundColor(R.drawable.delete_gray);    }    else {      delete.setBackgroundResource(R.drawable.delete);    }  }}

<LinearLayout 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:orientation="vertical"  tools:context="com.example.calculator.MainActivity" >  <RelativeLayout    android:layout_width="match_parent"    android:layout_height="wrap_content" >    <EditText      android:id="@+id/et_show"      android:layout_width="fill_parent"      android:layout_height="wrap_content"      android:hint="請輸入數字" />    <ImageView      android:id="@+id/iv_delete"      android:layout_width="wrap_content"      android:layout_height="wrap_content"      android:layout_alignRight="@id/et_show"      android:src="@drawable/delete_and_deletegray" >    </ImageView>  </RelativeLayout>  <GridLayout    android:layout_width="fill_parent"    android:layout_height="wrap_content"    android:layout_below="@+id/et_show"    android:focusable="false"    android:gravity="center"    android:layout_marginTop="25dp"    android:columnCount="4"    android:horizontalSpacing="0dp"    android:orientation="horizontal"    android:stretchMode="none" >    <Button      android:id="@+id/bt_1"      android:layout_height="wrap_content"      android:text="1" />    <Button      android:id="@+id/bt_2"      android:text="2" />    <Button      android:id="@+id/bt_3"      android:text="3" />    <Button      android:id="@+id/bt_div"      android:text="/" />    <Button      android:id="@+id/bt_4"      android:text="4" />    <Button      android:id="@+id/bt_5"      android:text="5" />    <Button      android:id="@+id/bt_6"      android:text="6" />    <Button      android:id="@+id/bt_mutilate"      android:text="X" />    <Button      android:id="@+id/bt_7"      android:text="7" />    <Button      android:id="@+id/bt_8"      android:text="8" />    <Button      android:id="@+id/bt_9"      android:text="9" />    <Button      android:id="@+id/bt_sub"      android:text="-" />    <Button      android:id="@+id/bt_0"      android:layout_columnSpan="2"      android:layout_gravity="fill_horizontal"      android:text="0"      android:width="2dp" />    <Button      android:id="@+id/bt_c"      android:layout_width="wrap_content"      android:layout_height="wrap_content"      android:text="C" />    <Button      android:id="@+id/bt_plus"      android:layout_gravity="fill_vertical"      android:layout_rowSpan="2"      android:text="+" />    <Button      android:id="@+id/bt_equ"      android:layout_columnSpan="3"      android:layout_gravity="fill_horizontal"      android:text="=" />  </GridLayout>  <TextView    android:id="@+id/author"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:text="Author:Bri"    />  <TextView    android:id="@+id/test"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:text="test:www.survivalescaperooms.com"    /></LinearLayout>

<?xml version="1.0" encoding="utf-8"?><selector xmlns:android="http://schemas.android.com/apk/res/android">  <item android:drawable="@drawable/delete_gray" android:state_focused="false" android:state_pressed="false"></item>  <item android:drawable="@drawable/delete" android:state_focused="false" android:state_pressed="false" android:state_selected="true"/>  <item android:drawable="@drawable/delete" android:state_pressed="true" android:state_selected="false"/>  <item android:drawable="@drawable/delete" android:state_focused="true" android:state_pressed="true"/></selector>