计算机

package com.example.df.firstapp;

 

import android.support.v7.app.AppCompatActivity;

import android.os.Bundle;

import android.view.View;

import android.widget.Button;  //引用按钮组件

import android.widget.EditText;  //引用文本编辑框组件

import android.text.TextUtils;  //TextUtils类用于处理字符串

 

//定义实现监听接口的类MainActivity

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

 

     //声明17个按钮和一个文本编辑框

     Button bt_num0,bt_num1,bt_num2,bt_num3,bt_num4,bt_num5,bt_num6,bt_num7,

bt_num8,bt_num9,bt_delete,bt_div,bt_mult,bt_minus,bt_plus,bt_equal,bt_dot,bt_clear;

    private EditText et_calc;

 

    @Override

    protected void onCreate(Bundle savedInstanceState) {  

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);  //显示activity_main.xml定义的用户界面

        initViewAndListener();  //调用函数initViewAndListener()

    }

 

    //定义函数initViewAndListener()，用于与用户界面程序中的组件建立关联，并分别注册监听接口

    private void initViewAndListener() {  

        bt_num0 = (Button)findViewById(R.id.bt_num0);

        bt_num0.setOnClickListener(this);

 

        bt_num1 = (Button)findViewById(R.id.bt_num1);

        bt_num1.setOnClickListener(this);

 

 

        bt_num2 =(Button) findViewById(R.id.bt_num2);

        bt_num2.setOnClickListener(this);

 

        bt_num3 = (Button)findViewById(R.id.bt_num3);

        bt_num3.setOnClickListener(this);

 

        bt_num4 = (Button)findViewById(R.id.bt_num4);

        bt_num4.setOnClickListener(this);

 

        bt_num5 = (Button)findViewById(R.id.bt_num5);

        bt_num5.setOnClickListener(this);

 

        bt_num6 = (Button)findViewById(R.id.bt_num6);

        bt_num6.setOnClickListener(this);

 

        bt_num7 = (Button)findViewById(R.id.bt_num7);

        bt_num7.setOnClickListener(this);

 

        bt_num8 = (Button)findViewById(R.id.bt_num8);

        bt_num8.setOnClickListener(this);

 

        bt_num9 = (Button)findViewById(R.id.bt_num9);

        bt_num9.setOnClickListener(this);

 

        bt_delete = (Button)findViewById(R.id.bt_delete);

        bt_delete.setOnClickListener(this);

 

        bt_div = (Button)findViewById(R.id.bt_div);

        bt_div.setOnClickListener(this);

 

        bt_mult = (Button)findViewById(R.id.bt_mult);

        bt_mult.setOnClickListener(this);

 

        bt_minus = (Button)findViewById(R.id.bt_minus);

        bt_minus.setOnClickListener(this);

 

 

        bt_plus = (Button)findViewById(R.id.bt_plus);

        bt_plus.setOnClickListener(this);

 

        bt_equal = (Button)findViewById(R.id.bt_equal);

        bt_equal.setOnClickListener(this);

 

        et_calc = (EditText)findViewById(R.id.et_calc);

 

        bt_dot = (Button)findViewById(R.id.bt_dot);

        bt_dot.setOnClickListener(this);

 

        bt_clear = (Button)findViewById(R.id.bt_clear);

        bt_clear.setOnClickListener(this);

 

    }

 

    private boolean lastIsOperator;  //记录当前是否进行计算操作

    private String lastOperators = "";  //记录上一次进行计算操作的结果

 

    private double firstNumber = 0D;  //定义并初始化第一次的取值

    private double sencondNumber = 0D;  //定义并初始化第二次的取值

 

    //onClick()方法，触发OnClickListener接口

    public void onClick(View v) {

        String currentText = et_calc.getText().toString();  //获取当前文本编辑框的内容

        String operatorNumber = "";  //定义并初始化操作数为””

        if (currentText.equals("0")) {  //若当前输入数为0则设置文本编辑框为””

            et_calc.setText("");

        }

        operatorNumber = et_calc.getText().toString();  //根据编辑框的内容更改操作数值

        if(!lastOperators.equals(""))  //判断上一次操作的数是否为空，非空则建立索引，随之修改当前操作数

        {

            int index = operatorNumber.lastIndexOf(lastOperators);

            operatorNumber = operatorNumber.substring(index+1);

        }

     

        //分别获取按钮的内容至文本编辑框

        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;

            //归零按钮，将当前操作数直接清零

            case R.id.bt_clear:

                et_calc.setText("");

                lastIsOperator = false;

                firstNumber=0D;

                sencondNumber=0D;

                lastOperators="=";

                break;

           //清除按钮，若当前文本编辑框内容为空，点击一次则删除一个字符串

            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;

            //计算按钮，若当前内容非空、或者以及上一次有操作记录且记录不是”=”的情况下，将当前的操作记录设置为+、-、*、/、=

            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;

        }

    }

 

   //运算函数，按具体操作进行+、-、*、/的运算

    private void operate(String operatorNumber)

    {

        if(sencondNumber != 0D)  //计算情况一：第二次输入的数不为0

        {

            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   //计算情况二：第二次输入的数为0

        {

            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);

            }

        }

    }

    //分别返回计算结果

public void opratorResult(String operatorNumber)

    {

        operate(operatorNumber);

 

}

//按当前计算结果进行下一次的数据输入及计算

    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);

 

    }

 

}

 

 

 

//布局文件activity_main.xml

<?xml version="1.0" encoding="utf-8"?>

<GridLayout 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="wrap_content"

    android:columnCount="4"    //设置了一个4列6行的网格

    android:rowCount="6"

    tools:context=".MainActivity"> 

 

    <EditText

        android:id="@+id/et_calc"

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:layout_columnSpan="4"  //该组件占据4列的位置

        android:layout_marginLeft="4px"

        android:gravity="left"

android:layout_row="0"

        android:background="#eee"

        android:textSize="50dip"/>

 

    <Button

        android:id="@+id/bt_delete"

        android:layout_column="3"

        android:layout_row="1"

        android:text="清除"

        android:textSize="26sp"/>

 

<Button

        android:id="@+id/bt_clear"

        android:layout_column="0"

        android:layout_row="1"

        android:text="归零"

        android:textSize="26sp"/>

 

    <Button

        android:id="@+id/bt_num1"

        android:layout_column="0"

        android:layout_row="2"

        android:text="1" 

android:textSize="26sp"/>

 

    <Button

        android:id="@+id/bt_num2"

        android:layout_column="1"

        android:layout_row="2"

        android:text="2" 

android:textSize="26sp"/>

 

    <Button

        android:id="@+id/bt_num3"

        android:layout_column="2"

        android:layout_row="2"

        android:text="3" 

android:textSize="26sp"/>

 

    <Button

        android:id="@+id/bt_plus"

        android:layout_column="3"

        android:layout_row="2"

        android:text="+" 

android:textSize="26sp"/>

 

    <Button

        android:id="@+id/bt_num4"

        android:layout_column="0"

        android:layout_row="3"

        android:text="4"

android:textSize="26sp" />

 

    <Button

        android:id="@+id/bt_num5"

        android:layout_column="1"

        android:layout_row="3"

        android:text="5" 

android:textSize="26sp"/>

 

    <Button

        android:id="@+id/bt_num6"

        android:layout_column="2"

        android:layout_row="3"

        android:text="6" 

android:textSize="26sp"/>

 

    <Button

        android:id="@+id/bt_minus"

        android:layout_column="3"

        android:layout_row="3"

        android:text="-"

android:textSize="26sp" />

 

    <Button

        android:id="@+id/bt_num7"

        android:layout_column="0"

        android:layout_row="4"

        android:text="7" 

android:textSize="26sp"/>

 

    <Button

        android:id="@+id/bt_num8"

        android:layout_column="1"

        android:layout_row="4"

        android:text="8" 

android:textSize="26sp"/>

 

    <Button

        android:id="@+id/bt_num9"

        android:layout_column="2"

        android:layout_row="4"

        android:text="9"

android:textSize="26sp" />

 

    <Button

        android:id="@+id/bt_mult"

        android:layout_column="3"

        android:layout_row="4"

        android:text="*" 

android:textSize="26sp" />

 

    <Button

        android:id="@+id/bt_dot"

        android:layout_column="0"

        android:layout_row="5"

        android:text="."

android:textSize="26sp" />

 

    <Button

        android:id="@+id/bt_num0"

        android:layout_column="1"

        android:layout_row="5"

        android:text="0"

android:textSize="26sp" />

 

    <Button

        android:id="@+id/bt_equal"

        android:layout_column="2"

        android:layout_row="5"

        android:text="="

android:textSize="26sp" />

 

    <Button

        android:id="@+id/bt_div"

        android:layout_column="3"

        android:layout_row="5"

        android:text="/"

android:textSize="26sp" />

</GridLayout>