Android开发实现的简单计算器功能【附完整demo源码下载】

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 = "先输入数值哦";
else {
showfirst = Integer.parseInt(showString);
showString = "";
option = "+";
}
break;
case R.id.bt_sub:
if (showString.equals(""))
exception = "先输入数值哦";
else {
showfirst = Integer.parseInt(showString);
showString = "";
option = "-";
}
break;
case R.id.bt_mutilate:
if (showString.equals(""))
exception = "先输入数值哦";
else {
showfirst = Integer.parseInt(showString);
showString = "";
option = "*";
}
break;
case R.id.bt_div:
if (showString.equals(""))
exception = "先输入数值哦";
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 = "除数不能为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, "郑明亮\n软件工程\nQQ：1072307340",
Toast.LENGTH_SHORT).show();
break;
default:
break;
}
if (exception.equals(""))
show.setText(showString);
else {
show.setText(exception);
exception = "";
}
// 设置文本框颜色；
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="请输入数字" / 
<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.zalou.cn"
/ 
</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