package com.example.myhomework2;

import androidx.appcompat.app.AppCompatActivity;

import android.app.ProgressDialog;

import android.os.Bundle;

import android.view.View;

import android.widget.EditText;

import android.widget.TextView;

public class MainActivity extends AppCompatActivity{

    double num1 = 0 , num2 = 0 , result = 0;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

    }

    public void click(View v){

        EditText et1 = findViewById(R.id.et1);

        EditText et2 = findViewById(R.id.et2);

        num1 = Double.parseDouble(et1.getText().toString());

        num2 = Double.parseDouble(et2.getText().toString());

        switch (v.getId())

        {

            case R.id.btn1:

                result = num1 + num2;

                break;

            case R.id.btn2:

                result = num1 - num2;

                break;

            case R.id.btn3:

                result = num1 * num2;

                break;

            case R.id.btn4:

                result = num1 / num2;

                break;

        }

    }

    public void click1(View v){

        TextView tv1 = findViewById(R.id.tv);

            /* @setProgress 设置初始进度

             * @setProgressStyle 设置样式（水平进度条）

             * @setMax 设置进度最大值

             */

            final int Max = 100;

            final ProgressDialog progressDialog = new ProgressDialog(MainActivity.this);

            progressDialog.setProgress(0);

            progressDialog.setTitle("正在计算,请稍等...");

            progressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);

            progressDialog.setMax(Max);

            progressDialog.show();

            /**

             * 开个线程

             */

            new Thread(new Runnable() {

                @Override

                public void run() {

                    int p = 0;

                    while (p <= Max){

                        try {

                            Thread.sleep(10);

                            p++;

                            progressDialog.setProgress(p);

                        }catch (Exception e){

                            e.printStackTrace();

                        }

                    }

                    progressDialog.cancel();//达到最大就消失

                }

            }).start();

        tv1.setText("计算结果:" + result + "");

    }

    public void click2(View v){

        EditText et1 = findViewById(R.id.et1);

        EditText et2 = findViewById(R.id.et2);

        TextView tv = findViewById(R.id.tv);

        et1.setText("");

        et2.setText("");

        tv.setText("");

    }

}

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

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"

    android:layout_width="match_parent"

    android:layout_height="match_parent"

    android:background="#789878">

    <EditText

        android:id="@+id/et1"

        android:layout_width="match_parent"

        android:layout_height="wrap_content" />

    <EditText

        android:id="@+id/et2"

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:layout_below="@id/et1" />

    <Button

        android:id="@+id/btn1"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:layout_below="@id/et2"

        android:onClick="click"

        android:text="+" />

    <Button

        android:id="@+id/btn2"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:layout_below="@id/et2"

        android:layout_toRightOf="@id/btn1"

        android:onClick="click"

        android:text="-" />

    <Button

        android:id="@+id/btn3"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:layout_below="@id/et2"

        android:layout_toRightOf="@id/btn2"

        android:onClick="click"

        android:text="*" />

    <Button

        android:id="@+id/btn4"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:layout_below="@id/et2"

        android:layout_toRightOf="@id/btn3"

        android:onClick="click"

        android:text="/" />

    <Button

        android:id="@+id/btn5"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:text="计算"

        android:textColor="#025588"

        android:background="#895865"

        android:layout_below="@id/btn1"

        android:layout_marginLeft="20dp"

        android:onClick="click1"

        />

    <Button

        android:id="@+id/btn6"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:text="清空"

        android:textColor="#025588"

        android:background="#895865"

        android:layout_below="@id/btn4"

        android:layout_toRightOf="@id/btn5"

        android:layout_marginLeft="135dp"

        android:onClick="click2"

        />

    <TextView

        android:id="@+id/tv"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:layout_below="@id/btn5"

        android:layout_marginTop="20dp"

        android:layout_marginLeft="20dp"

        android:text="计算结果:"

    />

</RelativeLayout>