学习Android写的计算器

学过一些简单的布局与编写代码的原理，模仿Windows的计算器，编写了一个简单的手机版本的。下一步是模仿iphone的计算器。下面是运行的效果图：

创建项目，命名为Calculator，首先编写布局文件，这里布局使用TableLayout，都是整行整列，使用它很方便，下面是布局文件的内容：

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:orientation="vertical"    android:layout_width="fill_parent"    android:layout_height="fill_parent"    android:background="@drawable/background"    >        <TableLayout    android:layout_marginTop="8px"    android:layout_width="fill_parent"    android:layout_height="fill_parent"    >    <TableRow>    <TextView    android:id="@+id/equation"    android:layout_weight="1"     android:gravity="right"    android:textColor="@color/black"    android:textSize="17px"    />    </TableRow>    <TableRow>    <TextView    android:id="@+id/result"    android:layout_weight="1"     android:gravity="right"    android:textColor="@color/black"    android:textSize="23px"    />    </TableRow>    <TableRow>    <Button    android:id="@+id/id7"    android:text="7"    android:layout_weight="1"     />    <Button    android:id="@+id/id8"    android:text="8"     android:layout_weight="1"    />    <Button    android:id="@+id/id9"    android:text="9"     android:layout_weight="1"    />    <Button    android:id="@+id/idDivid"    android:text="/"     android:layout_weight="1"    />    </TableRow>    <TableRow>    <Button    android:id="@+id/id4"    android:text="4"    android:layout_weight="1"     />    <Button    android:id="@+id/id5"    android:text="5"     android:layout_weight="1"    />    <Button    android:id="@+id/id6"    android:text="6"     android:layout_weight="1"    />    <Button    android:id="@+id/idMultiple"    android:text="*"     android:layout_weight="1"    />    </TableRow>    <TableRow>    <Button    android:id="@+id/id1"    android:text="1"    android:layout_weight="1"     />    <Button    android:id="@+id/id2"    android:text="2"     android:layout_weight="1"    />    <Button    android:id="@+id/id3"    android:text="3"     android:layout_weight="1"    />    <Button    android:id="@+id/idMinus"    android:text="-"     android:layout_weight="1"    />    </TableRow>    <TableRow>    <Button    android:id="@+id/id0"    android:text="0"    android:layout_weight="1"     />    <Button    android:id="@+id/iddot"    android:text="."     android:layout_weight="1"    />    <Button    android:id="@+id/idequal"    android:text="="    android:layout_weight="1"    />    <Button    android:id="@+id/idPlus"    android:text="+"     android:layout_weight="1"    />    </TableRow>    </TableLayout></LinearLayout>

然后是编写主Activity，这里把按钮分为两组，一组是数字，一组是运算符，分别给它们添加Listener，下面是代码：

package com.sinaapp.sheldonchen;import android.app.Activity;import android.os.Bundle;import android.widget.Button;import android.widget.TextView;public class CalculatorActivity extends Activity {protected final static String TAG = "CALCULATOR_ACTIVITY";private static int[] numbers = { R.id.id0, R.id.id1, R.id.id2, R.id.id3,R.id.id4, R.id.id5, R.id.id6, R.id.id7, R.id.id8, R.id.id9 };private static int[] ops = { R.id.idPlus, R.id.idMinus, R.id.idMultiple,R.id.idDivid, R.id.iddot, R.id.idequal };@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.main);TextView equationView = (TextView)this.findViewById(R.id.equation);TextView resultView = (TextView) this.findViewById(R.id.result);for (int number : numbers) {Button button = (Button) this.findViewById(number);button.setOnClickListener(new NumberButtonListener(resultView, equationView));}for (int op : ops) {Button button = (Button)this.findViewById(op);button.setOnClickListener(new OperationButtonListener(resultView, equationView));}}}

然后是处理数字的Listener：

package com.sinaapp.sheldonchen;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.TextView;public class NumberButtonListener implements OnClickListener {protected static final String TAG = "NUMBER_BUTTON";private TextView textView;private TextView equationView;public static boolean isNew = true;public NumberButtonListener(TextView textView, TextView equationView) {this.textView = textView;this.equationView = equationView;}@Overridepublic void onClick(View v) {Button b = null;if (v instanceof Button) {b = (Button) v;String result = textView.getText().toString();String text = b.getText().toString();if ((result.length() == 0 && text.equals("0"))|| result.trim().equals("0") || isNew == true) {this.equationView.setText("");result = text;isNew = false;} else {result += text;}textView.setText(result);}}}

接着是处理运算符的Listener：

package com.sinaapp.sheldonchen;import java.util.ArrayList;import java.util.LinkedList;import java.util.List;import android.util.Log;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.TextView;public class OperationButtonListener implements OnClickListener {protected static final String TAG = "OPERATION_BUTTON";private TextView resultView;private TextView equationView;private static String nowResult = null;private static List<String> list = new LinkedList<String>();private static int index = 0;private static List<String> opList = new ArrayList<String>();public OperationButtonListener(TextView resultView, TextView equationView) {this.resultView = resultView;this.equationView = equationView;opList.add("+");opList.add("-");opList.add("*");opList.add("/");}@Overridepublic void onClick(View v) {Button button = null;if (v instanceof Button) {Log.d(TAG, "list size: " + list.size());String result = resultView.getText().toString();button = (Button) v;int id = button.getId();if (id == R.id.iddot) {if (!result.contains(".")) {result += ".";}resultView.setText(result);} else if (id == R.id.idequal) {if (list.size() == 2) {String equation = this.equationView.getText().toString();if (equation.trim().equals("")) {equation = result;} else {equation = equation + " " + result;}this.equationView.setText(equation);double opt1 = Double.valueOf(list.get(0));String operation = list.get(1);list.remove(0);list.remove(0);double opt2 = Double.valueOf(result);if (operation.trim().equals("+")) {nowResult = String.valueOf((opt1 + opt2));} else if (operation.trim().equals("-")) {nowResult = String.valueOf((opt1 - opt2));} else if (operation.trim().equals("*")) {nowResult = String.valueOf((opt1 * opt2));} else if (operation.trim().equals("/")) {nowResult = String.valueOf((opt1 / opt2));}index = 0;NumberButtonListener.isNew = true;Log.v(TAG, "result: " + nowResult);this.resultView.setText(nowResult);}} else {String op = button.getText().toString();if (list.size() == 0 || opList.contains(list.get(list.size() - 1))) {list.add(index, result);index++;list.add(index, op);index++;}this.resultView.setText("");String equation = this.equationView.getText().toString();if (equation.trim().equals("")) {equation = result;} else {equation = equation + " " + result;}this.equationView.setText(equation + " " + op);if (list.size() == 4) {double opt1 = Double.valueOf((String) list.get(0));String operation = (String) list.get(1);Log.v(TAG, "operation: " + operation);double opt2 = Double.valueOf((String) list.get(2));if (operation.trim().equals("+")) {nowResult = String.valueOf((opt1 + opt2));} else if (operation.trim().equals("-")) {nowResult = String.valueOf((opt1 - opt2));} else if (operation.trim().equals("*")) {nowResult = String.valueOf((opt1 * opt2));} else if (operation.trim().equals("/")) {nowResult = String.valueOf((opt1 / opt2));}list.set(0, nowResult);list.set(1, list.get(3));index = 2;list.remove(2);list.remove(2);Log.v(TAG, "result: " + nowResult);NumberButtonListener.isNew = true;this.resultView.setText(nowResult);}}}}}

最后在res的values文件夹里，添加一个color.xml文件，内容如下：

<?xml version="1.0" encoding="utf-8"?><resources>      <color name="black">#000000</color>  </resources>

还需要一个背景图片，只要添加到drawable目录下，再把layout修改相应的值即可。