Android应用---简易计算器_安卓应用程序设计对话框计算器-优快云博客

本文介绍了一个简易计算器应用程序的开发过程，包括XML布局设计、MainActivity逻辑实现及菜单交互处理等关键步骤。该应用支持加减乘除四则运算，并集成了关于菜单项用于展示应用信息。

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主要代码：

activity_main.xml

</LinearLayout>

menu的activity_main.xml

MainActivity.java

package com.example.exercise02;

import java.text.DecimalFormat;

import com.example.biz.caculatorBiz;

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 MainActivity extends Activity {
private EditText num1Text;
private EditText num2Text;
private TextView opText;
private TextView result;
private Button add;
private Button sub;
private Button multiply;
private Button divide;
public static final int MENU_ABOUT = 0;
public static final int MENU_EXIT = 1;

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

initialComponent();
registerListener();

}

// 注册监听器
private void registerListener() {
  add.setOnClickListener(new ButtonHandler(){
   public void onClick(View v) {
    String num1String = num1Text.getText().toString().trim();
    String num2String = num2Text.getText().toString().trim();
    Log.e("第一个数：",num1String);
    Log.d("第二个数：",num2String);
    opText.setText("+");
    result.setText(Double.valueOf(new caculatorBiz().add(
      Double.parseDouble(num1String),
      Double.parseDouble(num2String))).toString() );
   }

  });
  sub.setOnClickListener(new ButtonHandler(){
   public void onClick(View v) {
    String num1String = num1Text.getText().toString().trim();
    String num2String = num2Text.getText().toString().trim();
    opText.setText("-");
    result.setText(Double.valueOf(new caculatorBiz().sub(
      Double.parseDouble(num1String),
      Double.parseDouble(num2String))).toString() );
   }
  });
  multiply.setOnClickListener(new ButtonHandler(){
   public void onClick(View v) {
    String num1String = num1Text.getText().toString().trim();
    String num2String = num2Text.getText().toString().trim();
    opText.setText("*");
    result.setText(Double.valueOf(new caculatorBiz().mulitply(
      Double.parseDouble(num1String),
      Double.parseDouble(num2String))).toString() );
   }
  });
  divide.setOnClickListener(new ButtonHandler(){
   public void onClick(View v) {
    String num1String = num1Text.getText().toString().trim();
    String num2String = num2Text.getText().toString().trim();
    opText.setText("/");
    result.setText(Double.valueOf(new caculatorBiz().divide(
      Double.parseDouble(num1String),
      Double.parseDouble(num2String))).toString() );
   }
  });
}

// 事件处理
public class ButtonHandler implements OnClickListener {
  // 接收数据
  String num1String = num1Text.getText().toString();
  String num2String = num2Text.getText().toString();
  caculatorBiz caculatorbiz = new caculatorBiz();

  // 判断点了哪一个按钮
  @Override
  public void onClick(View v) {
   switch (v.getId()) {
   case R.id.add:
    opText.setText("+");
    break;
   case R.id.sub:
    opText.setText("-");
    break;
   case R.id.multiply:
    opText.setText("*");
    break;
   case R.id.divide:
    if("0".trim().equals(num2String)){
     result.setText("");
     Toast.makeText(MainActivity.this,"注意！除数不能为0",Toast.LENGTH_LONG).show();
    }
    opText.setText("/");
    break;
   default:
    break;
   }
  }

  private String format(double result) {
   DecimalFormat decimalFormat = new DecimalFormat("0.00");
   return "" + decimalFormat.format(result);
  }

}

// 初始化组件
private void initialComponent() {
  num1Text = (EditText) this.findViewById(R.id.num1);
  num2Text = (EditText) this.findViewById(R.id.num2);
  opText = (TextView) this.findViewById(R.id.op);
  result = (TextView) this.findViewById(R.id.result);
  add = (Button) this.findViewById(R.id.add);
  sub = (Button) this.findViewById(R.id.sub);
  multiply = (Button) this.findViewById(R.id.multiply);
  divide = (Button) this.findViewById(R.id.divide);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
  menu.add(0, MENU_ABOUT, 0, R.string.about);// 第一个参数为组号，便于对整个组进行操作；第二个参数为菜单的ID，为了标识菜单项；第三个参数为显示顺序
  menu.add(0, MENU_EXIT, 1, R.string.exit);
  return true;
}
/**
* 当点击菜单项时调用
*/
@Override
public boolean onOptionsItemSelected(MenuItem item) {
  int itemId=item.getItemId();//获取菜单项的唯一编号
  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() {

    @Override
    public void onClick(DialogInterface dialog, int which) {
     Toast.makeText(MainActivity.this, "欢迎你的使用", Toast.LENGTH_LONG).show();
    }
   });
   alertDialog.setNegativeButton(R.string.cancel, new DialogInterface.OnClickListener() {

    @Override
    public void onClick(DialogInterface dialog, int which) {
    }
   });
   alertDialog.create().show();
   break;
  case MENU_EXIT:
   this.finish();//退出应用程序
  default:
   break;
  }
  return true;
}

}

业务逻辑类caulatorBiz.java

package com.example.biz;
/*
* 业务逻辑类
*/
public class caculatorBiz {
public double add(double n1, double n2) {
return n1 + n2;
}

public double sub(double n1, double n2) {
return n1 - n2;
}

public double mulitply(double n1, double n2) {
return n1 * n2;
}

public double divide(double n1, double n2) {
return n1 / n2;
}
}

strings.xml

    <string name="app_name">exercise02</string>
    <string name="hello_world">Hello world!</string>
    <string name="menu_settings">Settings</string>
    <string name="title_activity_main">运算器</string>
    <string name="op">运算符</string>

主要的运行截图：

打开activity: