Android 简单的计算器实现

谁践踏了优雅 2022-06-02 02:14 272阅读 0赞

android中实现一个简单的计算器，实现连续的加减乘除运算。  
首先，让我们看下布局：  
![这里写图片描述][SouthEast]

最上边是一个edittext 用来显示用户输入的运算数字和运算符，下面是一个TableLayout显示数字和运算符按钮。  
话不多说,主要代码如下：

package com.easygoing.androidcalculator;
    
    import android.support.v7.app.AppCompatActivity;
    import android.os.Bundle;
    import android.text.TextUtils;
    import android.util.Log;
    import android.view.View;
    import android.widget.Button;
    import android.widget.EditText;
    import android.widget.ListAdapter;
    
    import java.util.ArrayList;
    import java.util.List;
    
    public class MainActivity extends AppCompatActivity implements View.OnClickListener {
    
    
        private Button bt_num0;
        private Button bt_num1;
        private Button bt_num2;
        private Button bt_num3;
        private Button bt_num4;
        private Button bt_num5;
        private Button bt_num6;
        private Button bt_num7;
        private Button bt_num8;
        private Button bt_num9;
        private Button bt_clear;
        private Button bt_percent;
        private Button bt_delete;
        private Button bt_div;
        private Button bt_mult;
        private Button bt_minus;
        private Button bt_plus;
        private Button bt_equal;
        private Button bt_dot;
    
    
        private EditText et_calc;
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
    
            initViewAndListener();
    
        }
    
        private void initViewAndListener() {
            bt_num0 = findViewById(R.id.bt_num0);
            bt_num0.setOnClickListener(this);
    
            bt_num1 = findViewById(R.id.bt_num1);
            bt_num1.setOnClickListener(this);
    
    
            bt_num2 = findViewById(R.id.bt_num2);
            bt_num2.setOnClickListener(this);
    
            bt_num3 = findViewById(R.id.bt_num3);
            bt_num3.setOnClickListener(this);
    
            bt_num4 = findViewById(R.id.bt_num4);
            bt_num4.setOnClickListener(this);
    
            bt_num5 = findViewById(R.id.bt_num5);
            bt_num5.setOnClickListener(this);
    
            bt_num6 = findViewById(R.id.bt_num6);
            bt_num6.setOnClickListener(this);
    
            bt_num7 = findViewById(R.id.bt_num7);
            bt_num7.setOnClickListener(this);
    
            bt_num8 = findViewById(R.id.bt_num8);
            bt_num8.setOnClickListener(this);
    
            bt_num9 = findViewById(R.id.bt_num9);
            bt_num9.setOnClickListener(this);
    
    
            bt_clear = findViewById(R.id.bt_clear);
            bt_clear.setOnClickListener(this);
    
            bt_percent = findViewById(R.id.bt_percent);
            bt_percent.setOnClickListener(this);
    
            bt_delete = findViewById(R.id.bt_delete);
            bt_delete.setOnClickListener(this);
    
            bt_div = findViewById(R.id.bt_div);
            bt_div.setOnClickListener(this);
    
            bt_mult = findViewById(R.id.bt_mult);
            bt_mult.setOnClickListener(this);
    
            bt_minus = findViewById(R.id.bt_minus);
            bt_minus.setOnClickListener(this);
    
    
            bt_plus = findViewById(R.id.bt_plus);
            bt_plus.setOnClickListener(this);
    
            bt_equal = findViewById(R.id.bt_equal);
            bt_equal.setOnClickListener(this);
    
    
            et_calc = findViewById(R.id.et_calc);
    
            bt_dot = findViewById(R.id.bt_dot);
            bt_dot.setOnClickListener(this);
    
        }
    
    
        private boolean lastIsOperator;
        private String lastOperators = "";
        private List<String> operatorNumbers = new ArrayList<>();
        private List<String> operators = new ArrayList<>();;
    
        private double firstNumber = 0D;
        private double sencondNumber = 0D;
    
        @Override
        public void onClick(View v) {
    
            String currentText = et_calc.getText().toString();
    
            String operatorNumber = "";
    
            if (currentText.equals("0")) {
                et_calc.setText("");
            }
    
    
            operatorNumber = et_calc.getText().toString();
    
            if(!lastOperators.equals(""))
            {
                int index = operatorNumber.lastIndexOf(lastOperators);
                operatorNumber = operatorNumber.substring(index+1);
            }
    
    
    
    
            switch (v.getId()) {
                case R.id.bt_num0:
                    et_calc.setText(et_calc.getText() + "0");
                    lastIsOperator = false;
                    break;
                case R.id.bt_num1:
                    et_calc.setText(et_calc.getText() + "1");
                    lastIsOperator = false;
                    break;
                case R.id.bt_num2:
                    et_calc.setText(et_calc.getText() + "2");
                    lastIsOperator = false;
                    break;
                case R.id.bt_num3:
                    et_calc.setText(et_calc.getText() + "3");
                    lastIsOperator = false;
                    break;
                case R.id.bt_num4:
                    et_calc.setText(et_calc.getText() + "4");
                    lastIsOperator = false;
                    break;
                case R.id.bt_num5:
                    et_calc.setText(et_calc.getText() + "5");
                    lastIsOperator = false;
                    break;
                case R.id.bt_num6:
                    et_calc.setText(et_calc.getText() + "6");
                    lastIsOperator = false;
                    break;
                case R.id.bt_num7:
                    et_calc.setText(et_calc.getText() + "7");
                    lastIsOperator = false;
                    break;
                case R.id.bt_num8:
                    et_calc.setText(et_calc.getText() + "8");
                    lastIsOperator = false;
                    break;
                case R.id.bt_num9:
                    et_calc.setText(et_calc.getText() + "9");
                    lastIsOperator = false;
                    break;
                case R.id.bt_dot:
                    et_calc.setText(et_calc.getText() + ".");
                    lastIsOperator = false;
                    break;
                case R.id.bt_clear:
                    et_calc.setText("");
                    lastIsOperator = false;
                    firstNumber = 0D;
                    sencondNumber = 0D;
                    lastOperators ="=";
                    break;
                case R.id.bt_percent:
                    lastIsOperator = true;
                    break;
                case R.id.bt_delete:
                    if (TextUtils.isEmpty(et_calc.getText())) {
                        return;
                    }
                    lastIsOperator = false;
                    et_calc.setText(currentText.substring(0, currentText.length() - 1).length() > 0 ? currentText.substring(0, currentText.length() - 1) : "0");
                    break;
                case R.id.bt_div:
    
                    if ((TextUtils.isEmpty(et_calc.getText())
                            || lastIsOperator) && !lastOperators.equals("=")) {
                        return;
                    }
                    opratorCalc(operatorNumber,"÷");
                    lastIsOperator = true;
                    et_calc.setText(et_calc.getText() + "÷");
                    lastOperators = "÷";
                    break;
                case R.id.bt_mult:
                    if ((TextUtils.isEmpty(et_calc.getText())
                            || lastIsOperator) && !lastOperators.equals("=")) {
                        return;
                    }
                    opratorCalc(operatorNumber,"*");
                    lastIsOperator = true;
                    et_calc.setText(et_calc.getText() + "*");
                    lastOperators = "*";
                    break;
                case R.id.bt_minus:
                    if ((TextUtils.isEmpty(et_calc.getText())
                            || lastIsOperator) && !lastOperators.equals("=")) {
                        return;
                    }
                    opratorCalc(operatorNumber,"-");
                    lastIsOperator = true;
                    et_calc.setText(et_calc.getText() + "-");
                    lastOperators = "-";
                    break;
                case R.id.bt_plus:
                    if ((TextUtils.isEmpty(et_calc.getText())
                            || lastIsOperator) && !lastOperators.equals("=")) {
                        return;
                    }
                    opratorCalc(operatorNumber,"+");
                    lastIsOperator = true;
                    et_calc.setText(et_calc.getText() + "+");
                    lastOperators = "+";
                    break;
                case R.id.bt_equal:
                    double result = 0D;
                    if(TextUtils.isEmpty(lastOperators))
                    {
                        return;
                    }
                    opratorResult(operatorNumber);
                    sencondNumber = 0D;
                    lastOperators ="=";
                    lastIsOperator = true;
                    et_calc.setText(et_calc.getText() + "\n=" + String.valueOf(firstNumber));
                    break;
            }
        }
    
        private void operate(String operatorNumber)
        {
            if(sencondNumber != 0D)
            {
                if(lastOperators.equals("÷"))
                {
                    sencondNumber = sencondNumber / Double.parseDouble(operatorNumber);
                    firstNumber = firstNumber / sencondNumber;
                }
                else if(lastOperators.equals("*"))
                {
                    sencondNumber = sencondNumber * Double.parseDouble(operatorNumber);
                    firstNumber = firstNumber * sencondNumber;
                }
                else if(lastOperators.equals("+"))
                {
                    sencondNumber = Double.parseDouble(operatorNumber);
                    firstNumber = firstNumber + sencondNumber;
                }
                else if(lastOperators.equals("-"))
                {
                    sencondNumber = Double.parseDouble(operatorNumber);
                    firstNumber = firstNumber - sencondNumber;
                }
            }
            else
            {
                if(lastOperators.equals("÷"))
                {
                    firstNumber = firstNumber / Double.parseDouble(operatorNumber);
                }
                else if(lastOperators.equals("*"))
                {
                    firstNumber = firstNumber * Double.parseDouble(operatorNumber);
                }
                else if(lastOperators.equals("+"))
                {
                    firstNumber = firstNumber + Double.parseDouble(operatorNumber);
                }
                else if(lastOperators.equals("-"))
                {
                    firstNumber= firstNumber - Double.parseDouble(operatorNumber);
                }
    
    
            }
        }
        public void opratorResult(String operatorNumber)
        {
            operate(operatorNumber);
    
        }
        public void opratorCalc(String operatorNumber,String currentOprator)
        {
            if(TextUtils.isEmpty(lastOperators))
            {
                firstNumber = Double.parseDouble(operatorNumber);
                return;
            }
    
            if(lastOperators.equals(currentOprator))
            {
                if(lastOperators.equals("÷"))
                {
                    firstNumber = firstNumber / Double.parseDouble(operatorNumber);
                }
                else if(lastOperators.equals("*"))
                {
                    firstNumber = firstNumber * Double.parseDouble(operatorNumber);
                }
                else if(lastOperators.equals("+"))
                {
                    firstNumber = firstNumber + Double.parseDouble(operatorNumber);
                }
                else if(lastOperators.equals("-"))
                {
                    firstNumber = firstNumber - Double.parseDouble(operatorNumber);
                }
    
                return;
            }
            operate(operatorNumber);
    
        }
    
    }
    ```**重点内容**
    
    至于button的selector样式比较简单，这里简单贴出来两个：、
    
    
    
    
    
    <div class="se-preview-section-delimiter"></div>

普通button样式

<?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" tools:context="com.easygoing.androidcalculator.MainActivity">
    
        <EditText android:id="@+id/et_calc" style="@style/et_calc_style" />
    
        <TableLayout android:layout_width="match_parent" android:layout_height="wrap_content">
            <TableRow>
                <Button android:id="@+id/bt_clear" style="@style/bt_styles_common" android:background="@drawable/btn_background" android:text="C"/>
                <Button android:id="@+id/bt_percent" style="@style/bt_styles_common" android:background="@drawable/btn_background" android:text="+/-"/>
    
                <Button android:id="@+id/bt_delete" style="@style/bt_styles_common" android:background="@drawable/btn_background" android:text="Del" />
                <Button android:id="@+id/bt_div" style="@style/bt_styles_common" android:background="@drawable/btn_operate_background" android:textColor="#FFFFFF" android:text="÷"/>
            </TableRow>
    
            <TableRow>
                <Button android:id="@+id/bt_num7" style="@style/bt_styles_common" android:background="@drawable/btn_background" android:text="7"/>
                <Button android:id="@+id/bt_num8" style="@style/bt_styles_common" android:background="@drawable/btn_background" android:text="8"/>
                <Button android:id="@+id/bt_num9" style="@style/bt_styles_common" android:background="@drawable/btn_background" android:text="9"/>
                <Button android:id="@+id/bt_mult" style="@style/bt_styles_common" android:background="@drawable/btn_operate_background" android:textColor="#FFFFFF" android:text="×"/>
            </TableRow>
    
            <TableRow>
                <Button android:id="@+id/bt_num4" style="@style/bt_styles_common" android:background="@drawable/btn_background" android:text="4"/>
                <Button android:id="@+id/bt_num5" style="@style/bt_styles_common" android:background="@drawable/btn_background" android:text="5"/>
                <Button android:id="@+id/bt_num6" style="@style/bt_styles_common" android:background="@drawable/btn_background" android:text="6"/>
                <Button android:id="@+id/bt_minus" style="@style/bt_styles_common" android:background="@drawable/btn_operate_background" android:textColor="#FFFFFF" android:text="－"/>
            </TableRow>
            <TableRow>
                <Button android:id="@+id/bt_num1" style="@style/bt_styles_common" android:background="@drawable/btn_background" android:text="1"/>
                <Button android:id="@+id/bt_num2" style="@style/bt_styles_common" android:background="@drawable/btn_background" android:text="2"/>
                <Button android:id="@+id/bt_num3" style="@style/bt_styles_common" android:background="@drawable/btn_background" android:text="3"/>
                <Button android:id="@+id/bt_plus" style="@style/bt_styles_common" android:background="@drawable/btn_operate_background" android:textColor="#FFFFFF" android:text="＋"/>
            </TableRow>
            <TableRow>
                <Button android:id="@+id/bt_num0" style="@style/bt_styles_common" android:background="@drawable/btn_background" android:text="0"/>
                <Button android:id="@+id/bt_dot" style="@style/bt_styles_common" android:layout_weight="0.5" android:background="@drawable/btn_background" android:text="·"/>
                <Button android:id="@+id/bt_equal" style="@style/bt_styles_common" android:layout_weight="0.5" android:background="@drawable/btn_operate_background" android:textColor="#FFFFFF" android:text="＝"/>
            </TableRow>
        </TableLayout>
    </LinearLayout>

这里需要注意的一点就是再按钮0的布局那里，需要设置一样权重，让按钮0能够占两个按钮的长度，

代码的逻辑比较简单，主要是记录三个操作数和两个运算符，当有两个运算符的时候，比较运算符的优先级，先行运算，然后保存计算结果，详细的可以看下代码。

当然了，这个计算器的功能不是很完善，这里只不过是进行一个简单的示例，有兴趣的可以自己做一个。。

源代码下载地址：[http://download.csdn.net/download/qingyulove/10181313][http_download.csdn.net_download_qingyulove_10181313]

[SouthEast]: /images/20220602/448ac2549452470eb11afefbf7159f3a.png
[http_download.csdn.net_download_qingyulove_10181313]: http://download.csdn.net/download/qingyulove/10181313