效果图

package com.app.MyComputer;

import android.os.Bundle;

import android.view.View;

import android.view.View.OnClickListener;

import android.widget.Button;

import android.widget.EditText;

import android.widget.TextView;

import android.app.Activity;

public class MainActivity extends Activity implements OnClickListener {

//声明控件

Button btn0;//0键

Button btn1;//1键

Button btn2;//2键

Button btn3;//3键

Button btn4;//4键

Button btn5;//5键

Button btn6;//6键

Button btn7;//7键

Button btn8;//8键

Button btn9;//9键

Button btnC;//清除键

Button btnAdd;//+键

Button btnSub;//-键

Button btnMul;//*键

Button btnDiv;//除键

Button btnEqu;//等于键

Button btnDot;//点键

EditText tvResult;

//声明两个参数。接收tvResult前后的值

double num1 = 0, num2 = 0;

double Result = 0;//计算结果

int op = 0;//判断操作数，

String opd = " ";//显示操作符

boolean isClickEqu = false;//判断是否按了“=”按钮

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

//从布局文件中获取控件，

btn0 = (Button) findViewById(R.id.btn0);

btn1 = (Button) findViewById(R.id.btn1);

btn2 = (Button) findViewById(R.id.btn2);

btn3 = (Button) findViewById(R.id.btn3);

btn4 = (Button) findViewById(R.id.btn4);

btn5 = (Button) findViewById(R.id.btn5);

btn6 = (Button) findViewById(R.id.btn6);

btn7 = (Button) findViewById(R.id.btn7);

btn8 = (Button) findViewById(R.id.btn8);

btn9 = (Button) findViewById(R.id.btn9);

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

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

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

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

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

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

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

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

//添加监听

btn0.setOnClickListener(this);

btn1.setOnClickListener(this);

btn2.setOnClickListener(this);

btn3.setOnClickListener(this);

btn4.setOnClickListener(this);

btn5.setOnClickListener(this);

btn6.setOnClickListener(this);

btn7.setOnClickListener(this);

btn8.setOnClickListener(this);

btn9.setOnClickListener(this);

btnDot.setOnClickListener(this);

btnC.setOnClickListener(this);

btnAdd.setOnClickListener(this);

btnSub.setOnClickListener(this);

btnMul.setOnClickListener(this);

btnDiv.setOnClickListener(this);

btnEqu.setOnClickListener(this);

}

@Override

public void onClick(View v) {

switch (v.getId()) { //switch循环获取点击按钮后的值

case R.id.btn0: //获取，0-9、小数点，并在编辑框显示

String myString = tvResult.getText().toString();

myString += "0";

tvResult.setText(myString);

break;

case R.id.btn1:

String myString1 = tvResult.getText().toString();

myString1 += "1";

tvResult.setText(myString1);

break;

case R.id.btn2:

String myString2 = tvResult.getText().toString();

myString2 += "2";

tvResult.setText(myString2);

break;

case R.id.btn3:

String myString3 = tvResult.getText().toString();

myString3 += "3";

tvResult.setText(myString3);

break;

case R.id.btn4:

String myString4 = tvResult.getText().toString();

myString4 += "4";

tvResult.setText(myString4);

break;

case R.id.btn5:

String myString5 = tvResult.getText().toString();

myString5 += "5";

tvResult.setText(myString5);

break;

case R.id.btn6:

String myString6 = tvResult.getText().toString();

myString6 += "6";

tvResult.setText(myString6);

break;

case R.id.btn7:

String myString7 = tvResult.getText().toString();

myString7 += "7";

tvResult.setText(myString7);

break;

case R.id.btn8:

String myString8 = tvResult.getText().toString();

myString8 += "8";

tvResult.setText(myString8);

break;

case R.id.btn9:

String myString9 = tvResult.getText().toString();

myString9 += "9";

tvResult.setText(myString9);

break;

case R.id.btnAdd: //判断，使用加减乘除的操作符

String myStringAdd = tvResult.getText().toString();

if (myStringAdd.equals(null)) {

return;

}

num1 = Double.valueOf(myStringAdd);

tvResult.setText(null);

op = 1;

opd = "+";

break;

case R.id.btnSub:

String myStringSub = tvResult.getText().toString();

if (myStringSub.equals(null)) {

return;

}

num1 = Double.valueOf(myStringSub);

tvResult.setText(null);

op = 2;

opd = "-";

break;

case R.id.btnMul:

String myStringMul = tvResult.getText().toString();

if (myStringMul.equals(null)) {

return;

}

num1 = Double.valueOf(myStringMul);

tvResult.setText(null);

op = 3;

opd = "×";

break;

case R.id.btnDiv:

String myStringDiv = tvResult.getText().toString();

if (myStringDiv.equals(null)) {

return;

}

num1 = Double.valueOf(myStringDiv);

tvResult.setText(null);

op = 4;

opd = "÷";

break;

case R.id.btnC: //清除，将编辑框文本显示为空

tvResult.setText("");

Result = 0;

break;

case R.id.btnDot: //加入小数点·

String myStringDot = tvResult.getText().toString();

myStringDot += ".";

tvResult.setText(myStringDot);

break;

case R.id.btnEqu: //计算，以操作符为判断，选择所需的运算，并将结果输出

String myStringEqu = tvResult.getText().toString();

if (myStringEqu.equals(null)) {

return;

}

num2 = Double.valueOf(myStringEqu);

tvResult.setText(null);

switch (op) {

case 0:

Result = num2;

break;

case 1:

Result = num1 + num2;

break;

case 2:

Result = num1 - num2;

break;

case 3:

Result = num1 * num2;

break;

case 4:

if (num2 == 0) //除法中分子与分母之分

Result = 0;

else

Result = num1 / num2;

break;

default:

Result = 0;

break;

}

tvResult.setText(Double.toString(Result));

//tvResult.setText(Double.toString(num1) + opd + Double.toString(num2) + "=" + Double.toString(Result)); //将结果完整输出

op = 0;

break;

default:

break;

}

}

}

activity_main.xml

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

<androidx.constraintlayout.widget.ConstraintLayout 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="#000000"

>

<!--显示结果-->

<!--<LinearLayout

android:layout_width="fill_parent"

android:layout_height="wrap_content">

<TextView

android:id="@+id/tvResult"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:height="50dp"

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

</LinearLayout>-->

<EditText

android:id="@+id/tvResult"

android:layout_width="395dp"

android:layout_height="209dp"

android:focusable="false"

android:gravity="right"

android:text="0"

android:textColor="#FFFFFF"

android:textSize="85sp"

app:layout_constraintBottom_toTopOf="@+id/btnC"

app:layout_constraintEnd_toEndOf="parent"

app:layout_constraintHorizontal_bias="0.0"

app:layout_constraintStart_toStartOf="parent"

app:layout_constraintTop_toTopOf="parent"

app:layout_constraintVertical_bias="1.0" />

<Button

android:id="@+id/btnC"

android:layout_width="100dp"

android:layout_height="100dp"

android:width="75dp"

android:background="@drawable/circle1"

android:text="AC"

android:textAppearance="@style/TextAppearance.AppCompat.Display2"

android:textColor="@android:color/background_dark"

app:layout_constraintBottom_toTopOf="@+id/btn7"

app:layout_constraintEnd_toEndOf="parent"

app:layout_constraintHorizontal_bias="0.0"

app:layout_constraintStart_toStartOf="parent" />

<Button

android:id="@+id/btn0"

android:layout_width="100dp"

android:layout_height="100dp"

android:width="75dp"

android:background="@drawable/circle2"

android:text="0"

android:textAppearance="@style/TextAppearance.AppCompat.Display2"

android:textColor="#FFFFFF"

app:layout_constraintBottom_toBottomOf="parent"

app:layout_constraintStart_toStartOf="parent" />

<Button

android:id="@+id/btn1"

android:layout_width="100dp"

android:layout_height="100dp"

android:width="75dp"

android:background="@drawable/circle2"

android:text="1"

android:textAppearance="@style/TextAppearance.AppCompat.Display2"

android:textColor="#FFFFFF"

app:layout_constraintBottom_toTopOf="@+id/btn0"

app:layout_constraintStart_toStartOf="parent" />

<Button

android:id="@+id/btn2"

android:layout_width="100dp"

android:layout_height="100dp"

android:width="75dp"

android:background="@drawable/circle2"

android:text="2"

android:textAppearance="@style/TextAppearance.AppCompat.Display2"

android:textColor="#FFFFFF"

app:layout_constraintBottom_toTopOf="@+id/btnDot"

app:layout_constraintStart_toEndOf="@+id/btn1" />

<Button

android:id="@+id/btn3"

android:layout_width="100dp"

android:layout_height="100dp"

android:width="75dp"

android:background="@drawable/circle2"

android:bufferType="spannable"

android:text="3"

android:textAppearance="@style/TextAppearance.AppCompat.Display2"

android:textColor="#FFFFFF"

app:layout_constraintBottom_toTopOf="@+id/btnEqu"

app:layout_constraintStart_toEndOf="@+id/btn2" />

<Button

android:id="@+id/btn4"

android:layout_width="100dp"

android:layout_height="100dp"

android:width="75dp"

android:background="@drawable/circle2"

android:text="4"

android:textAppearance="@style/TextAppearance.AppCompat.Display2"

android:textColor="#FFFFFF"

app:layout_constraintBottom_toTopOf="@+id/btn1"

app:layout_constraintStart_toStartOf="parent" />

<Button

android:id="@+id/btn5"

android:layout_width="100dp"

android:layout_height="100dp"

android:width="75dp"

android:background="@drawable/circle2"

android:text="5"

android:textAppearance="@style/TextAppearance.AppCompat.Display2"

android:textColor="#FFFFFF"

app:layout_constraintBottom_toTopOf="@+id/btn2"

app:layout_constraintStart_toEndOf="@+id/btn4" />

<Button

android:id="@+id/btn6"

android:layout_width="100dp"

android:layout_height="100dp"

android:width="75dp"

android:background="@drawable/circle2"

android:text="6"

android:textAppearance="@style/TextAppearance.AppCompat.Display2"

android:textColor="#FFFFFF"

app:layout_constraintBottom_toTopOf="@+id/btn3"

app:layout_constraintStart_toEndOf="@+id/btn5" />

<Button

android:id="@+id/btn7"

android:layout_width="100dp"

android:layout_height="100dp"

android:layout_row="0"

android:layout_column="5"

android:width="75dp"

android:background="@drawable/circle2"

android:text="7"

android:textAppearance="@style/TextAppearance.AppCompat.Display2"

android:textColor="#FFFFFF"

app:layout_constraintBottom_toTopOf="@+id/btn4"

app:layout_constraintStart_toStartOf="parent" />

<Button

android:id="@+id/btn8"

android:layout_width="100dp"

android:layout_height="100dp"

android:width="75dp"

android:background="@drawable/circle2"

android:text="8"

android:textAppearance="@style/TextAppearance.AppCompat.Display2"

android:textColor="#FFFFFF"

app:layout_constraintBottom_toTopOf="@+id/btn5"

app:layout_constraintStart_toEndOf="@+id/btn7" />

<Button

android:id="@+id/btn9"

android:layout_width="100dp"

android:layout_height="100dp"

android:width="75dp"

android:background="@drawable/circle2"

android:text="9"

android:textAppearance="@style/TextAppearance.AppCompat.Display2"

android:textColor="#FFFFFF"

app:layout_constraintBottom_toTopOf="@+id/btn6"

app:layout_constraintStart_toEndOf="@+id/btn8" />

<Button

android:id="@+id/btnSub"

android:layout_width="100dp"

android:layout_height="100dp"

android:width="75dp"

android:background="@drawable/circle4"

android:text="一"

android:textAppearance="@style/TextAppearance.AppCompat.Body2"

android:textColor="#FFFFFF"

android:textSize="24sp"

app:layout_constraintBottom_toTopOf="@+id/btnAdd"

app:layout_constraintStart_toEndOf="@+id/btn3" />

<Button

android:id="@+id/btnAdd"

android:layout_width="100dp"

android:layout_height="100dp"

android:width="75dp"

android:background="@drawable/circle4"

android:text="+"

android:textAppearance="@style/TextAppearance.AppCompat.Display2"

android:textColor="#FFFFFF"

app:layout_constraintBottom_toBottomOf="parent"

app:layout_constraintStart_toEndOf="@+id/btnEqu" />

<Button

android:id="@+id/btnMul"

android:layout_width="100dp"

android:layout_height="100dp"

android:width="75dp"

android:background="@drawable/circle4"

android:text="×"

android:textAppearance="@style/TextAppearance.AppCompat.Display2"

android:textColor="#FDFFFFFF"

app:layout_constraintBottom_toTopOf="@+id/btnSub"

app:layout_constraintStart_toEndOf="@+id/btn6" />

<Button

android:id="@+id/btnDot"

android:layout_width="100dp"

android:layout_height="100dp"

android:width="10dp"

android:background="@drawable/circle2"

android:text="."

android:textAppearance="@style/TextAppearance.AppCompat.Display2"

android:textColor="#FFFFFF"

app:layout_constraintBottom_toBottomOf="parent"

app:layout_constraintStart_toEndOf="@+id/btn0" />

<Button

android:id="@+id/btnEqu"

android:layout_width="100dp"

android:layout_height="100dp"

android:width="75dp"

android:background="@drawable/circle2"

android:text="="

android:textAppearance="@style/TextAppearance.AppCompat.Display2"

android:textColor="#FFFFFF"

app:layout_constraintBottom_toBottomOf="parent"

app:layout_constraintStart_toEndOf="@+id/btnDot" />

<Button

android:id="@+id/btnDiv"

android:layout_width="100dp"

android:layout_height="100dp"

android:width="75dp"

android:background="@drawable/circle4"

android:text="/"

android:textAppearance="@style/TextAppearance.AppCompat.Display2"

android:textColor="#FFFFFF"

app:layout_constraintBottom_toTopOf="@+id/btnMul"

app:layout_constraintStart_toEndOf="@+id/btn9" />

</androidx.constraintlayout.widget.ConstraintLayout

 

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