简单计算机

package com.ct.mysimplecalculator;

import android.app.Activity;
import android.os.Bundle;
import android.text.InputType;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class MainActivity extends Activity implements OnClickListener {

    private Button[] btn = new Button[20];
    private Button calculator_return_btn;
    private EditText edittext;
    private String number = "";
    private double temp1, temp2;// 计算的第一个数和第二个数
    private int index;// + - * /的索引
    private double result = 0;// 运算的结果
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        getInstance();
    }
    
    private void getInstance(){
        btn[0] = (Button) findViewById(R.id.zero);
        btn[1] = (Button) findViewById(R.id.one);
        btn[2] = (Button) findViewById(R.id.two);
        btn[3] = (Button) findViewById(R.id.three);
        btn[4] = (Button) findViewById(R.id.four);
        btn[5] = (Button) findViewById(R.id.five);
        btn[6] = (Button) findViewById(R.id.six);
        btn[7] = (Button) findViewById(R.id.seven);
        btn[8] = (Button) findViewById(R.id.eight);
        btn[9] = (Button) findViewById(R.id.nine);
        btn[10] = (Button) findViewById(R.id.clean);
        btn[11] = (Button) findViewById(R.id.dot);
        btn[12] = (Button) findViewById(R.id.equal);
        btn[13] = (Button) findViewById(R.id.add);
        btn[14] = (Button) findViewById(R.id.subtraction);
        btn[15] = (Button) findViewById(R.id.multiply);
        btn[16] = (Button) findViewById(R.id.divide);
        btn[17] = (Button) findViewById(R.id.income);
        btn[18] = (Button) findViewById(R.id.expense);
        btn[19] = (Button) findViewById(R.id.transfer);
        calculator_return_btn=(Button) findViewById(R.id.calculator_return_btn);
        calculator_return_btn.setOnClickListener(this);
        edittext = (EditText) findViewById(R.id.screen);
        edittext.setInputType(InputType.TYPE_NULL);
        edittext.setText(number);
        for (int i = 0; i < 20; i++) {
            btn[i].setOnClickListener(this);
        }
    }
    
    private boolean idDouble(String str){
        try 
          { 
                Double.parseDouble(str); 
                return   true; 
          } 
          catch(NumberFormatException   ex){} 
          return   false; 
    }
    
    

    @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;
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
        case R.id.clean:
            if ("".equals(number)) {
                edittext.setText(number);
                edittext.setSelection(number.length());
            } else {
                number = number.substring(0, number.length() - 1);
                edittext.setText(number);
                edittext.setSelection(number.length());
                if (("".equals(number)) || ("-".equals(number))) {
                    edittext.setText(number);
                } else {
                    temp2 = Double.parseDouble(number);
                }
            }
            break;
        case R.id.add:
            if (!("".equals(number))) {
                edittext.setText(number);
                index = 0;
                temp1 = Double.parseDouble(number);
                number = "";
                temp2 = 0;
            }
            break;
        case R.id.subtraction:
            if (!("".equals(number))) {
                edittext.setText(number);
                index = 1;
                temp1 = Double.parseDouble(number);
                number = "";
                temp2 = 0;
            }
            break;
        case R.id.multiply:
            if (!("".equals(number))) {
                edittext.setText(number);
                index = 2;
                temp1 = Double.parseDouble(number);
                number = "";
                temp2 = 0;
                break;
            }
        case R.id.divide:
            if (!("".equals(number))) {
                edittext.setText(number);
                index = 3;
                temp1 = Double.parseDouble(number);
                number = "";
                temp2 = 0;
            }
            break;
        case R.id.dot:
            if(!(number.contains("."))){
                number += "0.";
                edittext.setText(number);
                break;
            }
        case R.id.income:
            String income = edittext.getText().toString();
            if(idDouble(income)){
                Bundle bundle=new Bundle();
                bundle.putInt("category", 1);//1表示收入,2表示支出,3表示转账
                bundle.putDouble("amount", Double.parseDouble(income));
                
                finish();
            }else{
                Toast.makeText(this, "不能记入，格式不正确", Toast.LENGTH_SHORT).show();
            }
            break;
        case R.id.expense:
            String expense = edittext.getText().toString();
            if(idDouble(expense)){
                Bundle bundle=new Bundle();
                bundle.putInt("category", 2);
                bundle.putDouble("amount", Double.parseDouble(expense));
                
                finish();
            }else{
                Toast.makeText(this, "不能记入，格式不正确", Toast.LENGTH_SHORT).show();
            }
            break;
        case R.id.transfer:
            String transfer = edittext.getText().toString();
            if(idDouble(transfer)){
                Bundle bundle=new Bundle();
                bundle.putInt("category", 3);
                bundle.putDouble("amount", Double.parseDouble(transfer));
                
                finish();
            }else{
                Toast.makeText(this, "不能记入，格式不正确", Toast.LENGTH_SHORT).show();
            }
            break;
        case R.id.equal:
            switch (index) {
            case 0:
                result = temp1 + temp2;
                edittext.setText(String.valueOf(result));
                number = String.valueOf(result);
                result = 0;
                break;
            case 1:
                result = temp1 - temp2;
                edittext.setText(String.valueOf(result));
                number = String.valueOf(result);
                result = 0;
                break;
            case 2:
                result = temp1 * temp2;
                edittext.setText(String.valueOf(result));
                number = String.valueOf(result);
                result = 0;
                break;
            case 3:
                if (temp2 == 0) {
                    edittext.setText("∞");
                    number = "";
                    result = 0;
                } else {
                    result = temp1 / temp2;
                    edittext.setText(String.valueOf(result));
                    number = String.valueOf(result);
                    result = 0;
                }
                break;
            default:
                break;
            }
            break;
        case R.id.calculator_return_btn:
            MainActivity.this.finish();
            break;
        default:
            Button btn = (Button) v;
            String temp = btn.getText().toString();
            number += temp;
            edittext.setText(number);
            temp2 = Double.parseDouble(number);
        }
    }

}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_gravity="center"
    android:background="@drawable/wallpaper"
    android:orientation="vertical" 
    >
    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="44dp" >

        <Button
            android:id="@+id/calculator_return_btn"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginLeft="8dp"
            android:layout_marginTop="8dp"
            android:text="返回"
            android:textSize="14sp" />

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_centerInParent="true"
            android:text="计算器"
            android:textSize="24sp" />
    </RelativeLayout>

    <EditText
        android:id="@+id/screen"
        android:layout_width="272dp"
        android:layout_height="64dp"
        android:layout_gravity="center"
        android:background="@drawable/calculator_screen_bg"
        android:cursorVisible="false"
        android:editable="false"
        android:inputType="numberDecimal"
        android:gravity="right|center_vertical"
        android:hint="0.00"
        android:textColor="@android:color/white"
        android:textColorHint="@android:color/white"
        android:textSize="45sp" 
        android:layout_marginTop="12dp"/>

    <TableLayout
        android:id="@+id/tableLayout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" >
        <TableRow
            android:id="@+id/row_1"
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:layout_marginTop="32dp"
            android:layout_weight="1"
            android:gravity="center" >

            <Button
                android:id="@+id/income"
                android:layout_width="55dp"
                android:layout_height="48dp"
                android:layout_marginLeft="8dp"
                android:layout_marginRight="8dp"
                android:background="@drawable/calculator_icon_bg"
                android:text="收入"
                android:textColor="@android:color/white"
                android:textSize="18sp" />

            <Button
                android:id="@+id/expense"
                android:layout_width="55dp"
                android:layout_height="48dp"
                android:layout_marginLeft="8dp"
                android:layout_marginRight="8dp"
                android:background="@drawable/calculator_icon_bg"
                android:text="支出"
                android:textColor="@android:color/white"
                android:textSize="18sp" />

            <Button
                android:id="@+id/transfer"
                android:layout_width="55dp"
                android:layout_height="48dp"
                android:layout_marginLeft="8dp"
                android:layout_marginRight="8dp"
                android:background="@drawable/calculator_icon_bg"
                android:text="转账"
                android:textColor="@android:color/white"
                android:textSize="18sp" />

            <Button
                android:id="@+id/clean"
                android:layout_width="55dp"
                android:layout_height="48dp"
                android:layout_marginLeft="8dp"
                android:layout_marginRight="8dp"
                android:background="@drawable/calculator_icon_bg"
                android:text="C"
                android:textColor="@android:color/white"
                android:textSize="30sp" />
        </TableRow>

        <TableRow
            android:id="@+id/row0"
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:layout_marginTop="16dp"
            android:layout_weight="1"
            android:gravity="center" >

            <Button
                android:id="@+id/one"
                android:layout_width="55dp"
                android:layout_height="48dp"
                android:layout_marginLeft="8dp"
                android:layout_marginRight="8dp"
                android:background="@drawable/calculator_icon_bg"
                android:text="1"
                android:textColor="@android:color/white"
                android:textSize="30sp" />

            <Button
                android:id="@+id/two"
                android:layout_width="55dp"
                android:layout_height="48dp"
                android:layout_marginLeft="8dp"
                android:layout_marginRight="8dp"
                android:background="@drawable/calculator_icon_bg"
                android:text="2"
                android:textColor="@android:color/white"
                android:textSize="30sp" />

            <Button
                android:id="@+id/three"
                android:layout_width="55dp"
                android:layout_height="48dp"
                android:layout_marginLeft="8dp"
                android:layout_marginRight="8dp"
                android:background="@drawable/calculator_icon_bg"
                android:text="3"
                android:textColor="@android:color/white"
                android:textSize="30sp" />

            <Button
                android:id="@+id/add"
                android:layout_width="55dp"
                android:layout_height="48dp"
                android:layout_marginLeft="8dp"
                android:layout_marginRight="8dp"
                android:background="@drawable/calculator_icon_bg"
                android:text="+"
                android:textColor="@android:color/white"
                android:textSize="30sp" />
        </TableRow>

        <TableRow
            android:id="@+id/row1"
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:layout_marginTop="16dp"
            android:layout_weight="1"
            android:gravity="center" >

            <Button
                android:id="@+id/four"
                android:layout_width="55dp"
                android:layout_height="48dp"
                android:layout_marginLeft="8dp"
                android:layout_marginRight="8dp"
                android:background="@drawable/calculator_icon_bg"
                android:text="4"
                android:textColor="@android:color/white"
                android:textSize="30sp" />

            <Button
                android:id="@+id/five"
                android:layout_width="55dp"
                android:layout_height="48dp"
                android:layout_marginLeft="8dp"
                android:layout_marginRight="8dp"
                android:background="@drawable/calculator_icon_bg"
                android:text="5"
                android:textColor="@android:color/white"
                android:textSize="30sp" />

            <Button
                android:id="@+id/six"
                android:layout_width="55dp"
                android:layout_height="48dp"
                android:layout_marginLeft="8dp"
                android:layout_marginRight="8dp"
                android:background="@drawable/calculator_icon_bg"
                android:text="6"
                android:textColor="@android:color/white"
                android:textSize="30sp" />

            <Button
                android:id="@+id/subtraction"
                android:layout_width="55dp"
                android:layout_height="48dp"
                android:layout_marginLeft="8dp"
                android:layout_marginRight="8dp"
                android:background="@drawable/calculator_icon_bg"
                android:text="-"
                android:textColor="@android:color/white"
                android:textSize="30sp" />
        </TableRow>

        <TableRow
            android:id="@+id/row2"
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:layout_marginTop="16dp"
            android:layout_weight="7"
            android:gravity="center" >

            <Button
                android:id="@+id/seven"
                android:layout_width="55dp"
                android:layout_height="48dp"
                android:layout_marginLeft="8dp"
                android:layout_marginRight="8dp"
                android:background="@drawable/calculator_icon_bg"
                android:text="7"
                android:textColor="@android:color/white"
                android:textSize="30sp" />

            <Button
                android:id="@+id/eight"
                android:layout_width="55dp"
                android:layout_height="48dp"
                android:layout_marginLeft="8dp"
                android:layout_marginRight="8dp"
                android:background="@drawable/calculator_icon_bg"
                android:text="8"
                android:textColor="@android:color/white"
                android:textSize="30sp" />

            <Button
                android:id="@+id/nine"
                android:layout_width="55dp"
                android:layout_height="48dp"
                android:layout_marginLeft="8dp"
                android:layout_marginRight="8dp"
                android:background="@drawable/calculator_icon_bg"
                android:text="9"
                android:textColor="@android:color/white"
                android:textSize="30sp" />

            <Button
                android:id="@+id/multiply"
                android:layout_width="55dp"
                android:layout_height="48dp"
                android:layout_marginLeft="8dp"
                android:layout_marginRight="8dp"
                android:background="@drawable/calculator_icon_bg"
                android:text="*"
                android:textColor="@android:color/white"
                android:textSize="30sp" />
        </TableRow>

        <TableRow
            android:id="@+id/row3"
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:layout_marginTop="16dp"
            android:layout_weight="0"
            android:gravity="center" >

            <Button
                android:id="@+id/zero"
                android:layout_width="55dp"
                android:layout_height="48dp"
                android:layout_marginLeft="8dp"
                android:layout_marginRight="8dp"
                android:background="@drawable/calculator_icon_bg"
                android:text="0"
                android:textColor="@android:color/white"
                android:textSize="30sp" />

            <Button
                android:id="@+id/dot"
                android:layout_width="55dp"
                android:layout_height="48dp"
                android:layout_marginLeft="8dp"
                android:layout_marginRight="8dp"
                android:background="@drawable/calculator_icon_bg"
                android:text="."
                android:textColor="@android:color/white"
                android:textSize="30sp" />

            <Button
                android:id="@+id/equal"
                android:layout_width="55dp"
                android:layout_height="48dp"
                android:layout_marginLeft="8dp"
                android:layout_marginRight="8dp"
                android:background="@drawable/calculator_icon_bg"
                android:text="="
                android:textColor="@android:color/white"
                android:textSize="30sp" />

            <Button
                android:id="@+id/divide"
                android:layout_width="55dp"
                android:layout_height="48dp"
                android:layout_marginLeft="8dp"
                android:layout_marginRight="8dp"
                android:background="@drawable/calculator_icon_bg"
                android:text="/"
                android:textColor="@android:color/white"
                android:textSize="30sp" />
        </TableRow>
    </TableLayout>

</LinearLayout>

（在F:\java\MySimpleCalculator）