Android开发简单的计算器

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);

转自：http://blog.csdn.net/nuptboyzhb/article/details/7832443