android应用程序--计算器

计算器在日常生活中用处还是比较大的，而且将其置入手机中，用起来更方便。而本次的任务是要运用MVC模式实现一个简易计算器。

阶段1、进行计算器的界面布局--V，这一阶段相对来说没有难度。

activity_calculate.xml文件：

string.xml文件中对各个控件的具体显示内容进行设置

    Calculate    Hello world!    Settings    CalculateActivity    运算符     =     +    -    *    /     关于    退出    作者：牛灵玉\n版本:2.0    确定    取消

阶段2、编写计算器的业务逻辑类--M，实现计算器的加、减、乘、除基本功能

package com.edu.nly.model;public class Calculator {  public double add(double a,double b){  return a+b;  }  public double sub(double a,double b){  return a-b;  }  public double mul(double a,double b){  return a*b;  }  public double div(double a,double b){  return a/b;  }}

阶段3、4、5、编写Activity---C，查找组件并进行事件处理

package com.edu.nly;import java.text.DecimalFormat;import com.edu.nly.model.Calculator;import android.os.Bundle;import android.app.Activity;import android.app.AlertDialog;import android.content.DialogInterface;import android.util.Log;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.TextView;import android.widget.Toast;public class CalculateActivity extends Activity {// 定义组件private EditText number1;// 操作数1文本框private EditText number2;// 操作数2文本框private TextView operate;// 运算符组件private TextView result;// 存放结果的组件private Button addButton;// 加法按钮组件private Button subButton;// 减法按钮组件private Button mulButton;// 乘法按钮组件private Button divButton;// 除法按钮组件private final static int MENU_ABOUT=1;private final static int MENU_EXIT=2;@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_calculate);initialComponents();registerListener();}    /*     * 注册监听事件     */private void registerListener() {addButton.setOnClickListener(new OnClickListener() {public void onClick(View v) {String num1String = number1.getText().toString().trim();String num2String = number2.getText().toString().trim();Log.e("第一个数：",num1String);Log.d("第二个数：",num2String);operate.setText("+");result.setText(Double.valueOf(new Calculator().add(Double.parseDouble(num1String),Double.parseDouble(num2String))).toString()  );}});subButton.setOnClickListener(new ButtonHander(){public void onClick(View v) {String num1String = number1.getText().toString().trim();String num2String = number2.getText().toString().trim();Log.e("第一个数：",num1String);Log.d("第二个数：",num2String);operate.setText("-");result.setText(Double.valueOf(calculator.sub(Double.parseDouble(num1String),Double.parseDouble(num2String))).toString());}});mulButton.setOnClickListener(new ButtonHander(){public void onClick(View v) {String num1String = number1.getText().toString().trim();String num2String = number2.getText().toString().trim();Log.e("第一个数：",num1String);Log.d("第二个数：",num2String);operate.setText("*");result.setText(format(calculator.mul(Double.parseDouble(num1String),Double.parseDouble(num2String))));}});divButton.setOnClickListener(new ButtonHander(){public void onClick(View v) {String num1String = number1.getText().toString().trim();String num2String = number2.getText().toString().trim();Log.e("第一个数：",num1String);Log.d("第二个数：",num2String);if("0".equals(num2String.trim())){Toast.makeText(CalculateActivity.this, "除数不能为零", Toast.LENGTH_LONG).show();}operate.setText("/");result.setText(format(calculator.div(Double.parseDouble(num1String),Double.parseDouble(num2String))));}});}/* * 自定义初始化组件 */private void initialComponents() {number1 = (EditText) this.findViewById(R.id.num1);number2 = (EditText) this.findViewById(R.id.num2);operate = (TextView) this.findViewById(R.id.operate);result = (TextView) this.findViewById(R.id.result);addButton = (Button) this.findViewById(R.id.add);subButton = (Button) this.findViewById(R.id.sub);mulButton = (Button) this.findViewById(R.id.mul);divButton = (Button) this.findViewById(R.id.div);}private class ButtonHander implements OnClickListener {String num1String = number1.getText().toString().trim();String num2String = number2.getText().toString().trim();     Calculator calculator = new Calculator();public void onClick(View v) {switch (v.getId()) {case R.id.add:operate.setText("+");break;case R.id.sub:operate.setText("-");break;case R.id.mul:operate.setText("*");break;case R.id.div:if("0".equals(num2String.trim())){Toast.makeText(CalculateActivity.this, "除数不能为零", Toast.LENGTH_LONG).show();break;}operate.setText("/");break;}}} public String format(double result) {DecimalFormat decimalFormat = new DecimalFormat("0.00");return decimalFormat.format(result);}@Overridepublic boolean onOptionsItemSelected(MenuItem item) {int itemId=item.getItemId();switch(itemId){case MENU_ABOUT:AlertDialog.Builder alertDialog=new AlertDialog.Builder(this);alertDialog.setIcon(android.R.drawable.ic_menu_help);//引用系统自带的图标alertDialog.setTitle(R.string.about);//给对话框设置标题alertDialog.setMessage(R.string.info);//设置对话框的提示信息alertDialog.setPositiveButton(R.string.ok, new DialogInterface.OnClickListener() {public void onClick(DialogInterface dialog, int which) {Toast.makeText(CalculateActivity.this, "欢迎你的使用", Toast.LENGTH_LONG).show();}});alertDialog.setNegativeButton(R.string.cancel, new DialogInterface.OnClickListener() {public void onClick(DialogInterface dialog, int which) {}});alertDialog.create().show();break;case MENU_EXIT:this.finish();break;}return true;}@Overridepublic boolean onCreateOptionsMenu(Menu menu) {menu.add(0, MENU_ABOUT, 1, R.string.about);menu.add(0, MENU_EXIT, 2, R.string.exit);return true;}}

经过上述操作之后的运行结果：

点击确定之后的运行结果：

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