代码地址：http://download.csdn.net/detail/nuptboyzhb/4478048
实现的最终界面：
开发中遇到的问题：ImageView的xml文件，出现src路径找不到的问题
<ImageViewandroid:id="@+id/photo1"
android:contentDescription="@string/app_name"
android:src="@drawable/zhb"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
上面的正确的代码，出问题时，android:src="@drawable-hdpi/zhb",此时，虽然drawable-hdpi文件夹下面有zhb.jpg图片，编辑器仍然报错，说找不到该资源。后来，我新建了一个drawable文件夹，将zhb.jpg剪切于此，就没有报错了！
代码：
package com.njupt.zhb.calculator;import android.os.Bundle;import android.R.bool;import android.R.integer;import android.app.Activity;import android.content.Intent;import android.view.Menu;import android.view.View;import android.widget.Button;import android.widget.EditText;import android.widget.TextView;import java.lang.*;import android.view.View.OnClickListener;public class MainActivity extends Activity { Button btn_num1; Button btn_num2; Button btn_num3; Button btn_num4; Button btn_num5; Button btn_num6; Button btn_num7; Button btn_num8; Button btn_num9; Button btn_num0; Button btnEqu; Button btnAdd; Button btnSub; Button btnMul; Button btnDiv; Button btnPoint; Button btnAbout; OnClickListener listener0=null; OnClickListener listener1=null; OnClickListener listener2=null; OnClickListener listener3=null; OnClickListener listener4=null; OnClickListener listener5=null; OnClickListener listener6=null; OnClickListener listener7=null; OnClickListener listener8=null; OnClickListener listener9=null; OnClickListener listenerEqu=null; OnClickListener listenerAdd=null; OnClickListener listenerSub=null; OnClickListener listenerMul=null; OnClickListener listenerDiv=null; OnClickListener listenerPoint=null; OnClickListener listenerAbout=null; CharSequence input_text=null; EditText displayText; TextView textview1; double num1=0; double num2=0; double result=0; int CalType=0; boolean EquBtnDownFlag=false; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); setTitle("计算器"); displayText=(EditText)findViewById(R.id.EditText1); displayText.setText(null); textview1=(TextView)findViewById(R.id.TextView1); btn_num0=(Button)findViewById(R.id.BtnNum0); btn_num1=(Button)findViewById(R.id.BtnNum1); btn_num2=(Button)findViewById(R.id.BtnNum2); btn_num3=(Button)findViewById(R.id.BtnNum3); btn_num4=(Button)findViewById(R.id.BtnNum4); btn_num5=(Button)findViewById(R.id.BtnNum5); btn_num6=(Button)findViewById(R.id.BtnNum6); btn_num7=(Button)findViewById(R.id.BtnNum7); btn_num8=(Button)findViewById(R.id.BtnNum8); btn_num9=(Button)findViewById(R.id.BtnNum9); btnAdd=(Button)findViewById(R.id.BtnAdd); btnSub=(Button)findViewById(R.id.BtnSubtract); btnMul=(Button)findViewById(R.id.BtnMul); btnDiv=(Button)findViewById(R.id.BtnDivide); btnPoint=(Button)findViewById(R.id.BtnNumPoint); btnEqu=(Button)findViewById(R.id.BtnEqual); btnAbout=(Button)findViewById(R.id.BtnAbout); listener0= new OnClickListener() { @Override public void onClick(View v) { // TODO Auto-generated method stub if (EquBtnDownFlag) { displayText.setText(null); EquBtnDownFlag=false; } CharSequence temp=displayText.getText(); String myString=temp.toString(); myString+="0"; displayText.setText(myString); } }; listener1= new OnClickListener() { @Override public void onClick(View v) { // TODO Auto-generated method stub if (EquBtnDownFlag) { displayText.setText(null); EquBtnDownFlag=false; } CharSequence temp=displayText.getText(); String myString=temp.toString(); myString+="1"; displayText.setText(myString); } }; listener2= new OnClickListener() { @Override public void onClick(View v) { // TODO Auto-generated method stub if (EquBtnDownFlag) { displayText.setText(null); EquBtnDownFlag=false; } CharSequence temp=displayText.getText(); String myString=temp.toString(); myString+="2"; displayText.setText(myString); } }; listener3= new OnClickListener() { @Override public void onClick(View v) { // TODO Auto-generated method stub if (EquBtnDownFlag) { displayText.setText(null); EquBtnDownFlag=false; } CharSequence temp=displayText.getText(); String myString=temp.toString(); myString+="3"; displayText.setText(myString); } }; listener4= new OnClickListener() { @Override public void onClick(View v) { // TODO Auto-generated method stub if (EquBtnDownFlag) { displayText.setText(null); EquBtnDownFlag=false; } CharSequence temp=displayText.getText(); String myString=temp.toString(); myString+="4"; displayText.setText(myString); } }; listener5= new OnClickListener() { @Override public void onClick(View v) { // TODO Auto-generated method stub if (EquBtnDownFlag) { displayText.setText(null); EquBtnDownFlag=false; } CharSequence temp=displayText.getText(); String myString=temp.toString(); myString+="5"; displayText.setText(myString); } }; listener6= new OnClickListener() { @Override public void onClick(View v) { // TODO Auto-generated method stub if (EquBtnDownFlag) { displayText.setText(null); EquBtnDownFlag=false; } CharSequence temp=displayText.getText(); String myString=temp.toString(); myString+="6"; displayText.setText(myString); } }; listener7= new OnClickListener() { @Override public void onClick(View v) { // TODO Auto-generated method stub if (EquBtnDownFlag) { displayText.setText(null); EquBtnDownFlag=false; } CharSequence temp=displayText.getText(); String myString=temp.toString(); myString+="7"; displayText.setText(myString); } }; listener8= new OnClickListener() { @Override public void onClick(View v) { // TODO Auto-generated method stub if (EquBtnDownFlag) { displayText.setText(null); EquBtnDownFlag=false; } CharSequence temp=displayText.getText(); String myString=temp.toString(); myString+="8"; displayText.setText(myString); } }; listener9= new OnClickListener() { @Override public void onClick(View v) { // TODO Auto-generated method stub if (EquBtnDownFlag) { displayText.setText(null); EquBtnDownFlag=false; } CharSequence temp=displayText.getText(); String myString=temp.toString(); myString+="9"; displayText.setText(myString); } }; listenerPoint= new OnClickListener() { @Override public void onClick(View v) { // TODO Auto-generated method stub if (EquBtnDownFlag) { displayText.setText(null); EquBtnDownFlag=false; } CharSequence temp=displayText.getText(); String myString=temp.toString(); myString+="."; displayText.setText(myString); } }; listenerAdd= new OnClickListener() { @Override public void onClick(View v) { // TODO Auto-generated method stub CharSequence temp=displayText.getText(); if (temp.equals(null)) { return; } String myString=temp.toString(); num1=Double.parseDouble(myString); CalType=1; displayText.setText(null); } }; listenerSub= new OnClickListener() { @Override public void onClick(View v) { // TODO Auto-generated method stub CharSequence temp=displayText.getText(); if (temp.equals(null)) { return; } String myString=temp.toString(); num1=Double.parseDouble(myString); CalType=2; displayText.setText(null); } }; listenerMul= new OnClickListener() { @Override public void onClick(View v) { // TODO Auto-generated method stub CharSequence temp=displayText.getText(); if (temp.equals(null)) { return; } String myString=temp.toString(); num1=Double.parseDouble(myString); CalType=3; displayText.setText(null); } }; listenerDiv= new OnClickListener() { @Override public void onClick(View v) { // TODO Auto-generated method stub CharSequence temp=displayText.getText(); if (temp.equals(null)) { return; } String myString=temp.toString(); num1=Double.parseDouble(myString); CalType=4; displayText.setText(null); } }; listenerEqu= new OnClickListener() { @Override public void onClick(View v) { // TODO Auto-generated method stub CharSequence temp=displayText.getText(); if (temp.equals(null)) { return; } String myString=temp.toString(); num2=Double.parseDouble(myString); switch(CalType) { case 0: result=num2; break; case 1: result=num1+num2; break; case 2: result=num1-num2; break; case 3: result=num1*num2; break; case 4: result=num1/num2; break; default: result=0; break; } String temp_result=String.valueOf(result); displayText.setText(temp_result); EquBtnDownFlag=true; } }; listenerAbout=new OnClickListener() { @Override public void onClick(View v) { // TODO Auto-generated method stub Intent intent1=new Intent(MainActivity.this,ActivityAbout.class); startActivity(intent1); } }; btn_num0.setOnClickListener(listener0); btn_num1.setOnClickListener(listener1); btn_num2.setOnClickListener(listener2); btn_num3.setOnClickListener(listener3); btn_num4.setOnClickListener(listener4); btn_num5.setOnClickListener(listener5); btn_num6.setOnClickListener(listener6); btn_num7.setOnClickListener(listener7); btn_num8.setOnClickListener(listener8); btn_num9.setOnClickListener(listener9); btnPoint.setOnClickListener(listenerPoint); btnAdd.setOnClickListener(listenerAdd); btnSub.setOnClickListener(listenerSub); btnMul.setOnClickListener(listenerMul); btnDiv.setOnClickListener(listenerDiv); btnEqu.setOnClickListener(listenerEqu); btnAbout.setOnClickListener(listenerAbout); } @Override public boolean onCreateOptionsMenu(Menu menu) { getMenuInflater().inflate(R.menu.activity_main, menu); return true; }}其实，当控件太多时，我们可以通过如下方式，减少Listener的数量：（http://rayleung.iteye.com/blog/539190）
View.OnClickListener handler = View.OnClickListener() { public void onClick(View v) { switch (v.getId()) { case R.id.Button01: // doStuff break; case R.id.Button02: // doStuff break; } }}findViewById(R.id.myButton).setOnClickListener(handler);findViewById(R.id.myOtherButton).setOnClickListener(handler);