摘要：
计算器的界面分为两大部分，第一部分是上方的计算表达式，既包括用户的按键输入，也包括计算结果数字;第二部分是下方的各个按键，例如:从0到9的数字按钮、加减乘除与等号、正负号按钮、小数点按钮、求倒数按钮、开方按钮以及删除、清空、取消等控制按钮
分析：
线性布局LinearLayout：计算器的整体布局是从上到下排列着的
网格布局GridLayout：计算器下半部分的几排按钮，正好成五行四列表格分布，适合采用GridLayout
滚动视图ScrollView：计算器界面如果超出屏幕大小，就要支持滚动
文本视图TextView：计算结果文本需要使用TextView，且文字靠下靠右显示
按钮Button：用于0-9的数字按键,以及加减乘除等运算按键
图像按钮ImageButton：开根号的运算符虽然能够打出来，但是右上角少了一横，所以该按钮要用一张标准的开根号图片显示
效果：
常量文件
1、buttonstyle.xml
宽高常量
<?xml version="1.0" encoding="utf-8"?> <resources> <dimen name="button_font_size">30sp</dimen> <dimen name="button_height">70dp</dimen> </resources>
2、strings.xml
<resources> <string name="app_name">SimpleControl</string> <string name="hello">世界未来与你相伴！！！</string> <string name="simple_calculator">计算器</string> <string name="cancel">CE</string> <string name="divide">÷</string> <string name="multiply">×</string> <string name="clear">C</string> <string name="seven">7</string> <string name="eight">8</string> <string name="nine">9</string> <string name="add">+</string> <string name="four">4</string> <string name="five">5</string> <string name="six">6</string> <string name="minus">-</string> <string name="one">1</string> <string name="two">2</string> <string name="three">3</string> <string name="reciprocal">1/x</string> <string name="zero">0</string> <string name="dot">.</string> <string name="equal">=</string> </resources>
3、AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.example.simplecontrol"> <application android:allowBackup="true" android:icon="@mipmap/ic_launcher" android:label="@string/app_name" android:roundIcon="@mipmap/ic_launcher_round" android:supportsRtl="true" android:theme="@style/Theme.SimpleControl"> <activity android:name=".CalculatorActivity" android:exported="true"> <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> </application> </manifest>
4、colors.xml
<?xml version="1.0" encoding="utf-8"?> <resources> <color name="purple_200">#FFBB86FC</color> <color name="purple_500">#FF6200EE</color> <color name="purple_700">#FF3700B3</color> <color name="teal_200">#FF03DAC5</color> <color name="teal_700">#FF018786</color> <color name="black">#FF000000</color> <color name="white">#FFFFFFFF</color> <color name="xian_green">#058531</color> <color name="gray">#666666</color> <color name="yellow">#FFFF00</color> <color name="red">#FF0033</color> <color name="blue">#0066CC</color> <color name="green">#33CC33</color> </resources>
5、themes.xml
<resources xmlns:tools="http://schemas.android.com/tools"> <!-- Base application theme. --> <style name="Theme.SimpleControl" parent="Theme.MaterialComponents.DayNight.DarkActionBar.Bridge"> <!-- Primary brand color. --> <item name="colorPrimary">@color/purple_500</item> <item name="colorPrimaryVariant">@color/purple_700</item> <item name="colorOnPrimary">@color/white</item> <!-- Secondary brand color. --> <item name="colorSecondary">@color/teal_200</item> <item name="colorSecondaryVariant">@color/teal_700</item> <item name="colorOnSecondary">@color/black</item> <!-- Status bar color. --> <item name="android:statusBarColor" tools:targetApi="l">?attr/colorPrimaryVariant</item> <!-- Customize your theme here. --> </style> </resources>
布局文件
1、activity_calculator.xml
<?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:background="#EEEEEE" android:orientation="vertical" android:padding="5dp"> <!--最外层的一个线性布局--> <!--垂直滚动页面--> <ScrollView android:layout_width="match_parent" android:layout_height="wrap_content"> <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="vertical"> <TextView android:layout_width="match_parent" android:layout_height="wrap_content" android:gravity="center" android:text="@string/simple_calculator" android:textColor="@color/green" android:textSize="50dp" /> <TextView android:layout_width="match_parent" android:layout_height="wrap_content" android:backgroundTint="#CCCCCC" android:lines="1" /> <TextView android:id="@+id/tv_result_calculator" android:layout_width="match_parent" android:layout_height="wrap_content" android:background="@color/white" android:gravity="bottom|right" android:lines="4" android:text="0" android:textColor="@color/black" android:textSize="25sp" /> <TextView android:layout_width="match_parent" android:layout_height="wrap_content" android:backgroundTint="#CCCCCC" android:lines="2" /> <!--网格布局设置 5 * 4 每一个按钮功能不一样--> <GridLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:columnCount="4" android:rowCount="5"> <Button android:id="@+id/btn_cancel" android:layout_width="0dp" android:layout_height="@dimen/button_height" android:layout_columnWeight="1" android:gravity="center" android:text="@string/cancel" android:textSize="@dimen/button_font_size" /> <Button android:id="@+id/btn_divide" android:layout_width="0dp" android:layout_height="@dimen/button_height" android:layout_columnWeight="1" android:gravity="center" android:text="@string/divide" android:textSize="@dimen/button_font_size" /> <Button android:id="@+id/btn_multiply" android:layout_width="0dp" android:layout_height="@dimen/button_height" android:layout_columnWeight="1" android:gravity="center" android:text="@string/multiply" android:textSize="@dimen/button_font_size" /> <Button android:id="@+id/btn_clear" android:layout_width="0dp" android:layout_height="@dimen/button_height" android:layout_columnWeight="1" android:gravity="center" android:text="@string/clear" android:textSize="@dimen/button_font_size" /> <Button android:id="@+id/btn_seven" android:layout_width="0dp" android:layout_height="@dimen/button_height" android:layout_columnWeight="1" android:gravity="center" android:text="@string/seven" android:textSize="@dimen/button_font_size" /> <Button android:id="@+id/btn_eight" android:layout_width="0dp" android:layout_height="@dimen/button_height" android:layout_columnWeight="1" android:gravity="center" android:text="@string/eight" android:textSize="@dimen/button_font_size" /> <Button android:id="@+id/btn_nine" android:layout_width="0dp" android:layout_height="@dimen/button_height" android:layout_columnWeight="1" android:gravity="center" android:text="@string/nine" android:textSize="@dimen/button_font_size" /> <Button android:id="@+id/btn_add" android:layout_width="0dp" android:layout_height="@dimen/button_height" android:layout_columnWeight="1" android:gravity="center" android:text="@string/add" android:textSize="@dimen/button_font_size" /> <Button android:id="@+id/btn_four" android:layout_width="0dp" android:layout_height="@dimen/button_height" android:layout_columnWeight="1" android:gravity="center" android:text="@string/four" android:textSize="@dimen/button_font_size" /> <Button android:id="@+id/btn_five" android:layout_width="0dp" android:layout_height="@dimen/button_height" android:layout_columnWeight="1" android:gravity="center" android:text="@string/five" android:textSize="@dimen/button_font_size" /> <Button android:id="@+id/btn_six" android:layout_width="0dp" android:layout_height="@dimen/button_height" android:layout_columnWeight="1" android:gravity="center" android:text="@string/six" android:textSize="@dimen/button_font_size" /> <Button android:id="@+id/btn_minus" android:layout_width="0dp" android:layout_height="@dimen/button_height" android:layout_columnWeight="1" android:gravity="center" android:text="@string/minus" android:textSize="@dimen/button_font_size" /> <Button android:id="@+id/btn_one" android:layout_width="0dp" android:layout_height="@dimen/button_height" android:layout_columnWeight="1" android:gravity="center" android:text="@string/one" android:textSize="@dimen/button_font_size" /> <Button android:id="@+id/btn_two" android:layout_width="0dp" android:layout_height="@dimen/button_height" android:layout_columnWeight="1" android:gravity="center" android:text="@string/two" android:textSize="@dimen/button_font_size" /> <Button android:id="@+id/btn_three" android:layout_width="0dp" android:layout_height="@dimen/button_height" android:layout_columnWeight="1" android:gravity="center" android:text="@string/three" android:textSize="@dimen/button_font_size" /> <ImageButton android:id="@+id/btn_sqrt" android:layout_width="0dp" android:layout_height="@dimen/button_height" android:layout_columnWeight="1" android:scaleType="centerInside" android:src="@drawable/sqrt"> </ImageButton> <Button android:id="@+id/btn_reciprocal" android:layout_width="0dp" android:layout_height="@dimen/button_height" android:layout_columnWeight="1" android:gravity="center" android:text="@string/reciprocal" android:textSize="@dimen/button_font_size" /> <Button android:id="@+id/btn_zero" android:layout_width="0dp" android:layout_height="@dimen/button_height" android:layout_columnWeight="1" android:gravity="center" android:text="@string/zero" android:textSize="@dimen/button_font_size" /> <Button android:id="@+id/btn_dot" android:layout_width="0dp" android:layout_height="@dimen/button_height" android:layout_columnWeight="1" android:gravity="center" android:text="@string/dot" android:textSize="@dimen/button_font_size" /> <Button android:id="@+id/btn_equal" android:layout_width="0dp" android:layout_height="@dimen/button_height" android:layout_columnWeight="1" android:gravity="center" android:text="@string/equal" android:textSize="@dimen/button_font_size" /> </GridLayout> </LinearLayout> </ScrollView> </LinearLayout>
逻辑处理代码
1、Calculator.java
package com.example.simplecontrol; import androidx.appcompat.app.AppCompatActivity; import android.os.Bundle; import android.view.View; import android.widget.TextView; import android.widget.Toast; import java.sql.Array; public class CalculatorActivity extends AppCompatActivity implements View.OnClickListener { private TextView tv_result_calculator; //第一个操作数 private String firstNum = ""; //运算符 private String operator = ""; //第二个操作数 private String secondNum = ""; //当前计算结果 private String result = ""; //显示的文本内容 private String showText = ""; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_calculator); //布局文件种获取tv_result_calculator文本视图 tv_result_calculator = findViewById(R.id.tv_result_calculator); //下面给每个按钮控件都注册了点击监听器 findViewById(R.id.btn_cancel).setOnClickListener(this); //"除法"按钮 findViewById(R.id.btn_divide).setOnClickListener(this); //"乘法”按钮 findViewById(R.id.btn_multiply).setOnClickListener(this); //"清除" 按钮 findViewById(R.id.btn_clear).setOnClickListener(this); //1 数字7 findViewById(R.id.btn_seven).setOnClickListener(this); //数字8 findViewById(R.id.btn_eight).setOnClickListener(this); //数字9 findViewById(R.id.btn_nine).setOnClickListener(this); //"加法"按钮 findViewById(R.id.btn_add).setOnClickListener(this); //数字4 findViewById(R.id.btn_four).setOnClickListener(this); //数字5 findViewById(R.id.btn_five).setOnClickListener(this); //数字6 findViewById(R.id.btn_six).setOnClickListener(this); //"减法" findViewById(R.id.btn_minus).setOnClickListener(this); //数字1按钮 findViewById(R.id.btn_one).setOnClickListener(this); //数字2 findViewById(R.id.btn_two).setOnClickListener(this); //数字3 findViewById(R.id.btn_three).setOnClickListener(this); //求倒数按钮 findViewById(R.id.btn_reciprocal).setOnClickListener(this); //数字0 findViewById(R.id.btn_zero).setOnClickListener(this); //"小数点" 按钮 findViewById(R.id.btn_dot).setOnClickListener(this); // "等号"按钮 findViewById(R.id.btn_equal).setOnClickListener(this); // "开平方"按钮 findViewById(R.id.btn_sqrt).setOnClickListener(this); } @Override public void onClick(View v) { String inputText; //如果是根号按钮 if (v.getId() == R.id.btn_sqrt) { inputText = "√"; } else { //其他的按钮 转换成文本内容 inputText = ((TextView) v).getText().toString(); } switch (v.getId()) { //清除按钮 case R.id.btn_clear: clear(); refreshText("0"); break; //取消按钮 case R.id.btn_cancel: if (operator.equals("")) { if (firstNum.length() == 1) { firstNum = "0"; } else if (firstNum.length() > 1) { firstNum = firstNum.substring(0, firstNum.length() - 1); } else { Toast.makeText(this, "0", Toast.LENGTH_SHORT).show(); } showText = firstNum; refreshText(showText); }else if(!operator.equals("") ){ if(secondNum.length() == 1){ secondNum = ""; }else if(secondNum.length() > 1){ secondNum = secondNum.substring(0,secondNum.length()-1); }else if(secondNum.length() == 0){ Toast.makeText(this,"0",Toast.LENGTH_SHORT).show(); } showText = showText.substring(0,showText.length()-1); refreshText(showText); } break; //加、减、乘、除按钮 case R.id.btn_add: case R.id.btn_minus: case R.id.btn_multiply: case R.id.btn_divide: //运算符 operator = inputText; refreshText(showText + operator); break; //等号按钮 case R.id.btn_equal: // 加减乘除进行四则运算 double calculate_result = calculateFour(); refreshOperate(String.valueOf(calculate_result)); refreshText(showText + "=" + result); break; //开根号按钮 case R.id.btn_sqrt: double sqrt_result = Math.sqrt(Double.parseDouble(firstNum)); refreshOperate(String.valueOf(sqrt_result)); refreshText(showText + "√=" + result); break; //求倒数按钮 case R.id.btn_reciprocal: double reciprocal = 1.0 / Double.parseDouble(firstNum); refreshOperate(String.valueOf(reciprocal)); refreshText(showText + "/=" + result); break; //其他按钮，包括数字和小数点 default: if (result.length() > 0 && operator.equals("")) { clear(); } // 判断是否为运算符 if (operator.equals("")) { //五运算符 firstNum = firstNum + inputText; } else { //有算符 secondNum = secondNum + inputText; } //整数不需要前面的 0 和 . if (showText.equals("0") && inputText.equals(".")) { //显示内容 refreshText(inputText); } else { refreshText(showText + inputText); } break; } } //四则运算 ,返回结果 private double calculateFour() { switch (operator) { case "+": return Double.parseDouble(firstNum) + Double.parseDouble(secondNum); case "-": return Double.parseDouble(firstNum) - Double.parseDouble(secondNum); case "×": return Double.parseDouble(firstNum) * Double.parseDouble(secondNum); default: return Double.parseDouble(firstNum) / Double.parseDouble(secondNum); } } //清空、并初始化 private void clear() { refreshOperate(""); refreshText(""); } //刷新运算结果 private void refreshOperate(String new_result) { result = new_result; //连续计算 下一次结果，就变成下一次计算的第一个数字 firstNum = result; secondNum = ""; operator = ""; } //刷新显示文本 public void refreshText(String text) { showText = text; tv_result_calculator.setText(showText); } }
初学者。
