AndroidStudio设计一个计算器

界面设计

activity_calcuator.xml 设计：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"

    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#EEEEEE"
    android:orientation ="vertical"
    android:padding="5dp">

    <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/black"
                android:textSize="20sp" />

            <TextView
                android:id="@+id/tv_result"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:background="@color/white"
                android:gravity="right|bottom"
                android:lines="3"
                android:text="0"
                android:textColor="@color/black"
                android:textSize="25sp" />

            <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="75dp"
                    android:layout_columnWeight="1"
                    android:gravity="center"
                    android:text="@string/cancel"
                    android:textColor="@color/black"
                    android:textSize="@dimen/button_font_size" />

                <Button
                    android:id="@+id/btn_divide"
                    android:layout_width="0dp"
                    android:layout_height="75dp"
                    android:layout_columnWeight="1"
                    android:gravity="center"
                    android:text="➗"
                    android:textColor="@color/black"
                    android:textSize="30sp" />

                <Button
                    android:id="@+id/btn_multiply"
                    android:layout_width="0dp"
                    android:layout_height="75dp"
                    android:layout_columnWeight="1"
                    android:gravity="center"
                    android:text="x"
                    android:textColor="@color/black"
                    android:textSize="30sp" />

                <Button
                    android:id="@+id/btn_clear"
                    android:layout_width="0dp"
                    android:layout_height="75dp"
                    android:layout_columnWeight="1"
                    android:gravity="center"
                    android:text="C"
                    android:textColor="@color/black"
                    android:textSize="30sp" />

                <Button
                    android:id="@+id/btn_seven"
                    android:layout_width="0dp"
                    android:layout_height="75dp"
                    android:layout_columnWeight="1"
                    android:gravity="center"
                    android:text="7"
                    android:textColor="@color/black"
                    android:textSize="30sp" />

                <Button
                    android:id="@+id/btn_eight"
                    android:layout_width="0dp"
                    android:layout_height="75dp"
                    android:layout_columnWeight="1"
                    android:gravity="center"
                    android:text="8"
                    android:textColor="@color/black"
                    android:textSize="30sp" />

                <Button
                    android:id="@+id/btn_nine"
                    android:layout_width="0dp"
                    android:layout_height="75dp"
                    android:layout_columnWeight="1"
                    android:gravity="center"
                    android:text="9"
                    android:textColor="@color/black"
                    android:textSize="30sp" />

                <Button
                    android:id="@+id/btn_plus"
                    android:layout_width="0dp"
                    android:layout_height="75dp"
                    android:layout_columnWeight="1"
                    android:gravity="center"
                    android:text="+"
                    android:textColor="@color/black"
                    android:textSize="30sp" />

                <Button
                    android:id="@+id/btn_four"
                    android:layout_width="0dp"
                    android:layout_height="75dp"
                    android:layout_columnWeight="1"
                    android:gravity="center"
                    android:text="4"
                    android:textColor="@color/black"
                    android:textSize="30sp" />

                <Button
                    android:id="@+id/btn_five"
                    android:layout_width="0dp"
                    android:layout_height="75dp"
                    android:layout_columnWeight="1"
                    android:gravity="center"
                    android:text="5"
                    android:textColor="@color/black"
                    android:textSize="30sp" />
                <Button
                    android:id="@+id/btn_six"
                    android:layout_width="0dp"
                    android:layout_height="75dp"
                    android:layout_columnWeight="1"
                    android:gravity="center"
                    android:text="6"
                    android:textColor="@color/black"
                    android:textSize="30sp" />

                <Button
                    android:id="@+id/btn_minus"
                    android:layout_width="0dp"
                    android:layout_height="75dp"
                    android:layout_columnWeight="1"
                    android:gravity="center"
                    android:text="-"
                    android:textColor="@color/black"
                    android:textSize="30sp" />

                <Button
                    android:id="@+id/btn_one"
                    android:layout_width="0dp"
                    android:layout_height="75dp"
                    android:layout_columnWeight="1"
                    android:gravity="center"
                    android:text="1"
                    android:textColor="@color/black"
                    android:textSize="30sp" />

                <Button
                    android:id="@+id/btn_two"
                    android:layout_width="0dp"
                    android:layout_height="75dp"
                    android:layout_columnWeight="1"
                    android:gravity="center"
                    android:text="2"
                    android:textColor="@color/black"
                    android:textSize="30sp" />

                <Button
                    android:id="@+id/btn_three"
                    android:layout_width="0dp"
                    android:layout_height="75dp"
                    android:layout_columnWeight="1"
                    android:gravity="center"
                    android:text="3"
                    android:textColor="@color/black"
                    android:textSize="30sp" />

                <ImageButton
                    android:id="@+id/ib_sqrt"
                    android:layout_width="0dp"
                    android:layout_height="@dimen/button_height"
                    android:layout_columnWeight="1"
                    android:scaleType="centerInside"
                    android:src="@drawable/sqtr" />

                <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:textColor="@color/black"
                    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:textColor="@color/black"
                    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:textColor="@color/black"
                    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:textColor="@color/black"
                    android:textSize="@dimen/button_font_size" />

            </GridLayout>

        </LinearLayout>

    </ScrollView>

</LinearLayout>

dimens.xml

<resources>
    <dimen name="fab_margin">16dp</dimen>

    <dimen name="button_font_size">30sp</dimen>
    <dimen name="button_height">75dp</dimen>
</resources>

strings.xml

<resources>
    <string name="app_name">chapter03</string>
    <string name="action_settings">Settings</string>
    <!-- Strings used for fragments for navigation -->
    <string name="first_fragment_label">First Fragment</string>
    <string name="second_fragment_label">Second Fragment</string>
    <string name="next">Next</string>
    <string name="previous">Previous</string>

    <string name="hello">你好，世界</string>
    <string name="simple_calculator">牛逼算器</string>
    <string name="cancel">CE</string>
    <string name="divide">➗</string>
    <string name="multiply">x</string>
    <string name="clear">C</string>
    <string name="seven">7</string>
    <string name="eight">8</string>
    <string name="nine">9</string>
    <string name="plus">+</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>

CalcuatorActivity.java逻辑代码：

package com.example.myapplication;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.TextView;

public class CalcuatorActivity extends AppCompatActivity {

    private TextView tv_result;

    //第一个操作数
    private String firstNum = "";
    //运算符
    private String operator = "";
    //第二个操作数
    private String secondNum = "";
    //当前的计算结果
    private String result = "";
    //显示的文本内容
    private String showText = "";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Log.d("CalcuatorActiviy","onCreat() method called");
        setContentView(R.layout.activity_calcuator);

        //从布局中获取名交tv_result的文本视图
        tv_result = findViewById(R.id.tv_result);
        //下面每个按钮控件都组册了点击监听
        findViewById(R.id.btn_cancel).setOnClickListener((View.OnClickListener) this);
        findViewById(R.id.btn_divide).setOnClickListener((View.OnClickListener) this);
        findViewById(R.id.btn_multiply).setOnClickListener((View.OnClickListener) this);
        findViewById(R.id.btn_clear).setOnClickListener((View.OnClickListener) this);
        findViewById(R.id.btn_seven).setOnClickListener((View.OnClickListener) this);
        findViewById(R.id.btn_eight).setOnClickListener((View.OnClickListener) this);
        findViewById(R.id.btn_nine).setOnClickListener((View.OnClickListener) this);
        findViewById(R.id.btn_plus).setOnClickListener((View.OnClickListener) this);
        findViewById(R.id.btn_four).setOnClickListener((View.OnClickListener) this);
        findViewById(R.id.btn_five).setOnClickListener((View.OnClickListener) this);
        findViewById(R.id.btn_six).setOnClickListener((View.OnClickListener) this);
        findViewById(R.id.btn_minus).setOnClickListener((View.OnClickListener) this);
        findViewById(R.id.btn_one).setOnClickListener((View.OnClickListener) this);
        findViewById(R.id.btn_two).setOnClickListener((View.OnClickListener) this);
        findViewById(R.id.btn_three).setOnClickListener((View.OnClickListener) this);
        findViewById(R.id.btn_reciprocal).setOnClickListener((View.OnClickListener) this);
        findViewById(R.id.btn_zero).setOnClickListener((View.OnClickListener) this);
        findViewById(R.id.btn_dot).setOnClickListener((View.OnClickListener) this);
        findViewById(R.id.btn_equal).setOnClickListener((View.OnClickListener) this);
        findViewById(R.id.ib_sqrt).setOnClickListener((View.OnClickListener) this);
    }

    //@Override
    public void onClick(View v){
        String inputText;
        //如果是开根号按钮
        if(v.getId() == R.id.ib_sqrt){
            inputText = "√";
        }else{
            //除了开根号之外的其他按钮
            inputText = ((TextView) v).getText().toString();
        }
        switch(v.getId()){
            //点击了清除按钮
            case R.id.btn_clear:
                clear();
                break;
            //点击了取消按钮
            case R.id.btn_cancel:
                break;
            //点击了加减乘除
            case R.id.btn_plus:
            case R.id.btn_minus:
            case R.id.btn_multiply:
            case R.id.btn_divide:
                operator = inputText;//运算符
                refreshText(showText + operator);
                break;
            //等号按钮
            case R.id.btn_equal:
                //加减乘除四则运算
                double calculate_result = calculateFour();
                refreshOperate(String.valueOf(calculate_result));
                refreshText(showText + "=" + result);
            // 开根号按钮
            case R.id.ib_sqrt:
                double sqrt_result = Math.sqrt(Double.parseDouble(firstNum));
                refreshOperate(String.valueOf(sqrt_result));
                refreshText(showText + "√=" + result);
                break;
            //点击了求倒数按钮
            case R.id.btn_reciprocal:
                double reciprocal_result = 1.0/Double.parseDouble(firstNum);
                refreshOperate(String.valueOf(reciprocal_result));
                refreshText(showText + "/=" + result);
                break;
            default:
                //上次结果已经出来了
                if(result.length()>0&&operator.equals("")){
                    clear();
                }

                //无运算符，则继续拼接第一个操作数
                if(operator.equals("")){
                    firstNum = firstNum + inputText;
                }else{
                //有运算符，则继续拼接第二个操作符
                    secondNum = secondNum + inputText;
                }
                if(showText.equals("0")&&!inputText.equals(".")){
                    refreshText(inputText);
                }else {
                    refreshText(showText + inputText);
                }
                break;
        }
    }

    //四则运算，返回计算结果
    private double calculateFour(){
        switch (operator){
            case "+":
                return Double.parseDouble(firstNum) + Double.parseDouble(secondNum);
            case "-":
                return Double.parseDouble(firstNum) - Double.parseDouble(secondNum);
            case "8":
                return Double.parseDouble(firstNum) * Double.parseDouble(secondNum);
            default:
                return Double.parseDouble(firstNum) / Double.parseDouble(secondNum);
        }
    }

    private  void clear(){
        refreshOperate("");
        refreshText("");
    }

    //刷新运算结果
    private void refreshOperate(String new_result){
        result = new_result;
        firstNum = result;
        secondNum = "";
        operator = "";
    }

    //刷新文本显示
    private void refreshText(String text){
        showText = text;
        tv_result.setText(showText);
    }

}

这完全是前端的领域我觉得