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Android学习之简易计算器
  1. CalculatorActivity.java
  2. activity_calculator.xml
  3. strings.xml
  4. 图片

CalculatorActivity.java

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package com.example.chapter03;

import androidx.appcompat.app.AppCompatActivity;

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

public class CalculatorActivity extends AppCompatActivity implements View.OnClickListener{

    private TextView tv_result;
    private String firstNum = "";
    private String secondNum = "";

    private String operator = "";

    private String result = "";

    private String showText = "";


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_calculator);
        tv_result = findViewById(R.id.tv_result);
        findViewById(R.id.btn_cancel).setOnClickListener(this);
        findViewById(R.id.btn_divide).setOnClickListener(this);
        findViewById(R.id.btn_multiply).setOnClickListener(this);
        findViewById(R.id.btn_clear).setOnClickListener(this);
        findViewById(R.id.btn_seven).setOnClickListener(this);
        findViewById(R.id.btn_eight).setOnClickListener(this);
        findViewById(R.id.btn_nine).setOnClickListener(this);
        findViewById(R.id.btn_plus).setOnClickListener(this);
        findViewById(R.id.btn_four).setOnClickListener(this);
        findViewById(R.id.btn_five).setOnClickListener(this);
        findViewById(R.id.btn_six).setOnClickListener(this);
        findViewById(R.id.btn_minus).setOnClickListener(this);
        findViewById(R.id.btn_one).setOnClickListener(this);
        findViewById(R.id.btn_two).setOnClickListener(this);
        findViewById(R.id.btn_three).setOnClickListener(this);
        findViewById(R.id.ib_sqrt).setOnClickListener(this);
        findViewById(R.id.btn_reciprocal).setOnClickListener(this);
        findViewById(R.id.btn_zero).setOnClickListener(this);
        findViewById(R.id.btn_dot).setOnClickListener(this);
        findViewById(R.id.btn_equal).setOnClickListener(this);
    }

    @Override
    public void onClick(View view) {
        //这是输入的文字
        String inputText;

        if(view.getId() == R.id.ib_sqrt)
        {
            //因为根号是图片按钮，所以需要特殊处理
            inputText = "√";

        }
        else
        {
            //剩下的直接获取文字即可
            inputText = ((TextView)view).getText().toString();
        }
        //
        if(view.getId() == R.id.btn_clear)
        {
            clear();
        }
        else if(view.getId() == R.id.btn_cancel)
        {
        }
        else if(view.getId() == R.id.btn_plus)
        {
            operator = inputText;
            refreshText(showText+operator);
        }
        else if(view.getId() == R.id.btn_minus)
        {
            operator = inputText;
            refreshText(showText+operator);
        }
        else if(view.getId() == R.id.btn_multiply)
        {
            operator = inputText;
            refreshText(showText+operator);
        }
        else if(view.getId() == R.id.btn_divide)
        {
            operator = inputText;
            refreshText(showText+operator);
        }
        else if(view.getId() == R.id.btn_equal)
        {
            double calculate_result = calculate_four();
            refreshOperate(String.valueOf(calculate_four()));
            refreshText(showText+"="+result);

        }
        else if(view.getId() == R.id.ib_sqrt)
        {
            double sqrt_result = Math.sqrt(Double.parseDouble(firstNum));
            refreshOperate(String.valueOf(sqrt_result));
            refreshText(showText+"√="+result);
        }
        else if(view.getId() == R.id.btn_reciprocal)
        {
            double reciprocal_result = 1/Double.parseDouble(firstNum);
            refreshOperate(String.valueOf(reciprocal_result));
            refreshText(showText+"/="+result);
        }
        else
        {
            if (result.length() > 0 && operator.equals(""))
            {
                clear();
            }


            if(operator.equals(""))
            {
                firstNum = firstNum + inputText;
            }
            else
            {
                secondNum = secondNum + inputText;
            }
            if (showText.equals("0") && !inputText.equals("."))
            {
                refreshText(inputText);

            }
            else
            {
                refreshText(showText+inputText);
            }

        }



    }

    private double calculate_four()
    {
        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);
            case "/":
                return Double.parseDouble(firstNum) / Double.parseDouble(secondNum);
            default:
                return 0;
        }



    }

    private void refreshText(String text)
    {
        //改变showText
        showText = text;

        tv_result.setText(showText);
    }
    private void refreshOperate(String new_result)
    {
        //1.等号后重置运算符，result为计算的结果，并作为新的第一个数字
        result = new_result;
        firstNum = result;
        //清空第二个数字
        secondNum = "";
        //清空运算符
        operator = "";

    }
    private void clear()
    {
        refreshOperate("");
        refreshText("0");

    }
}

activity_calculator.xml

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<?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:orientation="vertical"
    android:background="#eeeeee"
    android:padding="5dp"
    tools:context=".CalculatorActivity">
    <ScrollView
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <LinearLayout
            android:layout_width="match_parent"
            android:orientation="vertical"
            android:layout_height="wrap_content">
            <TextView
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="@string/simple_calculator"
                android:gravity="center"
                android:textColor="@color/black"
                android:textSize="20sp"/>
            <TextView
                android:id="@+id/tv_result"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="0"
                android:textColor="@color/black"
                android:textSize="25sp"
                android:lines="3"
                android:gravity="right|bottom"/>
            <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:textSize="@dimen/button_font_size"
                    android:textColor="@color/black"
                    android:gravity="center"

                    android:text="@string/cancel"/>
                <Button
                    android:id="@+id/btn_divide"
                    android:layout_width="0dp"
                    android:layout_height="@dimen/button_height"
                    android:layout_columnWeight="1"
                    android:textSize="@dimen/button_font_size"
                    android:textColor="@color/black"
                    android:gravity="center"

                    android:text="@string/divide"/>
                <Button
                    android:id="@+id/btn_multiply"
                    android:layout_width="0dp"
                    android:layout_height="@dimen/button_height"
                    android:layout_columnWeight="1"
                    android:textSize="@dimen/button_font_size"
                    android:textColor="@color/black"
                    android:gravity="center"

                    android:text="@string/multiply"/>
                <Button
                    android:id="@+id/btn_clear"
                    android:layout_width="0dp"
                    android:layout_height="@dimen/button_height"
                    android:layout_columnWeight="1"
                    android:textSize="@dimen/button_font_size"
                    android:textColor="@color/black"
                    android:gravity="center"

                    android:text="@string/clear"/>
                <Button
                    android:id="@+id/btn_seven"
                    android:layout_width="0dp"
                    android:layout_height="@dimen/button_height"
                    android:layout_columnWeight="1"
                    android:textSize="@dimen/button_font_size"
                    android:textColor="@color/black"
                    android:gravity="center"

                    android:text="@string/seven"/>
                <Button
                    android:id="@+id/btn_eight"
                    android:layout_width="0dp"
                    android:layout_height="@dimen/button_height"
                    android:layout_columnWeight="1"
                    android:textSize="@dimen/button_font_size"
                    android:textColor="@color/black"
                    android:gravity="center"

                    android:text="@string/eight"/>
                <Button
                    android:id="@+id/btn_nine"
                    android:layout_width="0dp"
                    android:layout_height="@dimen/button_height"
                    android:layout_columnWeight="1"
                    android:textSize="@dimen/button_font_size"
                    android:textColor="@color/black"
                    android:gravity="center"

                    android:text="@string/nine"/>
                <Button
                    android:id="@+id/btn_plus"
                    android:layout_width="0dp"
                    android:layout_height="@dimen/button_height"
                    android:layout_columnWeight="1"
                    android:textSize="@dimen/button_font_size"
                    android:textColor="@color/black"
                    android:gravity="center"

                    android:text="@string/plus"/>
                <Button
                    android:id="@+id/btn_four"
                    android:layout_width="0dp"
                    android:layout_height="@dimen/button_height"
                    android:layout_columnWeight="1"
                    android:textSize="@dimen/button_font_size"
                    android:textColor="@color/black"
                    android:gravity="center"

                    android:text="@string/four"/>
                <Button
                    android:id="@+id/btn_five"
                    android:layout_width="0dp"
                    android:layout_height="@dimen/button_height"
                    android:layout_columnWeight="1"
                    android:textSize="@dimen/button_font_size"
                    android:textColor="@color/black"
                    android:gravity="center"

                    android:text="@string/five"/>
                <Button
                    android:id="@+id/btn_six"
                    android:layout_width="0dp"
                    android:layout_height="@dimen/button_height"
                    android:layout_columnWeight="1"
                    android:textSize="@dimen/button_font_size"
                    android:textColor="@color/black"
                    android:gravity="center"

                    android:text="@string/six"/>
                <Button
                    android:id="@+id/btn_minus"
                    android:layout_width="0dp"
                    android:layout_height="@dimen/button_height"
                    android:layout_columnWeight="1"
                    android:textSize="@dimen/button_font_size"
                    android:textColor="@color/black"
                    android:gravity="center"

                    android:text="@string/minus"/>
                <Button
                    android:id="@+id/btn_one"
                    android:layout_width="0dp"
                    android:layout_height="@dimen/button_height"
                    android:layout_columnWeight="1"
                    android:textSize="@dimen/button_font_size"
                    android:textColor="@color/black"
                    android:gravity="center"

                    android:text="@string/one"/>
                <Button
                    android:id="@+id/btn_two"
                    android:layout_width="0dp"
                    android:layout_height="@dimen/button_height"
                    android:layout_columnWeight="1"
                    android:textSize="@dimen/button_font_size"
                    android:textColor="@color/black"
                    android:gravity="center"

                    android:text="@string/two"/>
                <Button
                    android:id="@+id/btn_three"
                    android:layout_width="0dp"
                    android:layout_height="@dimen/button_height"
                    android:layout_columnWeight="1"
                    android:textSize="@dimen/button_font_size"
                    android:textColor="@color/black"
                    android:gravity="center"

                    android:text="@string/three"/>
                <ImageButton
                    android:id="@+id/ib_sqrt"
                    android:layout_width="0dp"
                    android:layout_height="@dimen/button_height"
                    android:layout_columnWeight="1"
                    android:src="@drawable/sqrt"
                    android:gravity="center"
                    android:scaleType="fitCenter"/>
                <Button
                    android:id="@+id/btn_reciprocal"
                    android:layout_width="0dp"
                    android:layout_height="@dimen/button_height"
                    android:layout_columnWeight="1"
                    android:textSize="@dimen/button_font_size"
                    android:textColor="@color/black"
                    android:gravity="center"

                    android:text="@string/reciprocal"/>
                <Button
                    android:id="@+id/btn_zero"
                    android:layout_width="0dp"
                    android:layout_height="@dimen/button_height"
                    android:layout_columnWeight="1"
                    android:textSize="@dimen/button_font_size"
                    android:textColor="@color/black"
                    android:gravity="center"

                    android:text="@string/zero"/>
                <Button
                    android:id="@+id/btn_dot"
                    android:layout_width="0dp"
                    android:layout_height="@dimen/button_height"
                    android:layout_columnWeight="1"
                    android:textSize="@dimen/button_font_size"
                    android:textColor="@color/black"
                    android:gravity="center"

                    android:text="@string/dot"/>
                <Button
                    android:id="@+id/btn_equal"
                    android:layout_width="0dp"
                    android:layout_height="@dimen/button_height"
                    android:layout_columnWeight="1"
                    android:textSize="@dimen/button_font_size"
                    android:textColor="@color/black"
                    android:gravity="center"

                    android:text="@string/equal"/>








            </GridLayout>



        </LinearLayout>
    </ScrollView>


</LinearLayout>

strings.xml

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<resources>
    <string name="app_name">chapter03</string>
    <string name="hello">你好，世界</string>
    <string name="simple_calculator">简单计算器</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="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="dot">.</string>
    <string name="equal">=</string>
    <string name="zero">0</string>




</resources>

图片

成品

2023-09-21 该篇文章被 QuietFall 打上标签: Android

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