Android计算器简单逻辑实现实例分享

引言：

　　我的android计算器的实现方式是：按钮输入一次，就处理一次。

　　但是如果你学过数据结构（栈），就可以使用表达式解析（前缀，后缀）处理。

　　而这个方式已经很成熟了，但是时间有限，只完成了这个简单的计算器。

　　至于，这个Android的布局已经在我博客中发布了，不再讲述。　　　　


代码如下:

package com.example.androidlessontwo;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

public class MainActivity extends Activity  {

private Button[] buttonNum=new Button[11];
    private Button[] buttonComand=new Button[5];
    private TextView input=null;
    private TextView rl=null;
    private Button   buttonClear=null;
    private boolean firstFlag=true;
    private double result=0.0;
    private String lastCommand;

public void MyCalculator()
    {
        result = 0.0;
        firstFlag=true;
        lastCommand="=";
    }
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        buttonNum[0]=(Button) findViewById(R.id.num0);
        buttonNum[1]=(Button) findViewById(R.id.num1);
        buttonNum[2]=(Button) findViewById(R.id.num2);
        buttonNum[3]=(Button) findViewById(R.id.num3);
        buttonNum[4]=(Button) findViewById(R.id.num4);
        buttonNum[5]=(Button) findViewById(R.id.num5);
        buttonNum[6]=(Button) findViewById(R.id.num6);
        buttonNum[7]=(Button) findViewById(R.id.num7);
        buttonNum[8]=(Button) findViewById(R.id.num8);
        buttonNum[9]=(Button) findViewById(R.id.num9);
        buttonNum[10]=(Button) findViewById(R.id.point);

buttonComand[0]=(Button) findViewById(R.id.add);
        buttonComand[1]=(Button) findViewById(R.id.sub);
        buttonComand[2]=(Button) findViewById(R.id.ride);
        buttonComand[3]=(Button) findViewById(R.id.divide);
        buttonComand[4]=(Button) findViewById(R.id.equal);

input=(TextView) findViewById(R.id.input);
        rl   =(TextView) findViewById(R.id.rl);
        buttonClear=(Button) findViewById(R.id.clean);

NumberAction na= new NumberAction();
        CommandAction ca=new CommandAction();
        for(Button bc:buttonComand)
        {
            bc.setOnClickListener(ca);
        }
        for(Button bc:buttonNum)
        {
            bc.setOnClickListener(na);
        }
        buttonClear.setOnClickListener(new Button.OnClickListener()
        {

@Override
            public void onClick(View v) {
                MyCalculator();
                rl.setText("0.0");
            }
        });
    }
    @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;
    }
    private class NumberAction implements Button.OnClickListener
    {

@Override
        public void onClick(View view)
        {
            Button btn = (Button)view;
            String inputTemp =btn.getText().toString();//6
            input.setText(input.getText().toString()+inputTemp);   
            double numtemp = 0;
            switch(btn.getId())
            {
                case R.id.num0:
                {
                    if(firstFlag)
                        {
                            result=result*10+0;
                            firstFlag=false;
                        }
                    else
                        numtemp=numtemp*10+0;
                    break;
                }
                case R.id.num1:
                {
                    if(firstFlag)
                        {
                        result=result*10+1;
                            firstFlag=false;
                        }
                    else
                        numtemp=numtemp*10+1;
                    break;
                }
                case R.id.num2:
                {
                    if(firstFlag)
                        {
                        result=result*10+2;
                            firstFlag=false;
                        }
                    else
                        numtemp=numtemp*10+2;
                    break;
                }
                case R.id.num3:
                {
                    if(firstFlag)
                        {
                        result=result*10+3;
                            firstFlag=false;
                        }
                    else
                        numtemp=numtemp*10+3;
                    break;
                }
                case R.id.num4:
                {
                    if(firstFlag)
                        {
                        result=result*10+4;
                            firstFlag=false;
                        }
                    else
                        numtemp=numtemp*10+4;
                    break;
                }
                case R.id.num5:
                {
                    if(firstFlag)
                        {
                        result=result*10+5;
                            firstFlag=false;
                        }
                    else
                        numtemp=numtemp*10+5;
                    break;
                }
                case R.id.num6:
                {
                    if(firstFlag)
                        {
                        result=result*10+6;
                            firstFlag=false;
                        }
                    else
                        {
                            numtemp=numtemp*10+6;
                            calculate(numtemp);
                        }
                    break;
                }
                case R.id.num7:
                {
                    if(firstFlag)
                        {
                            result=result*10+7;
                            firstFlag=false;
                        }
                    else
                    {
                        numtemp=numtemp*10+7;
                        calculate(numtemp);
                    }
                    break;
                }
                case R.id.num8:
                {
                    if(firstFlag)
                        {
                        result=result*10+8;
                            {
                                result=result*10+8;
                                firstFlag=false;
                            }
                        }
                    else
                        {
                            numtemp=numtemp*10+8;
                            calculate(numtemp);
                        }
                    break;
                }
                case R.id.num9:
                {
                    if(firstFlag)
                        {
                        result=result*10+9;
                            firstFlag=false;
                        }
                    else
                        {
                            numtemp=numtemp*10+9;
                            calculate(numtemp);
                        }
                    break;
                }   
            }

}

}

private class CommandAction implements Button.OnClickListener
    {
        @Override
        public void onClick(View v)
        {
            Button btn=(Button)v;
            String inputCommand=(String)btn.getText();
            switch(btn.getId())
            {
                case R.id.add:
                {
                    lastCommand="+";
                    break;
                }
                case R.id.sub:
                {
                    lastCommand="-";
                    break;
                }
                case R.id.ride:
                {
                    lastCommand="*";
                    break;
                }
                case R.id.divide:
                {
                    lastCommand="/";
                    break;
                }
                case R.id.equal:
                {
                    lastCommand="=";
                    input.setText("");
                    rl.setText(String.valueOf(result));
                    return ;
                }

}
            input.setText(input.getText()+inputCommand);   
        }

}
    private void calculate(double x)
    {

if(lastCommand.equals("+"))
            {
                result += x;
            }

if(lastCommand.equals("-"))
            {
                result -= x;
            }

if(lastCommand.equals("*"))
            {
                result *= x;
            }

if(lastCommand.equals("/"))
            {
                result /= x;
            }
    }

}