Android Studio制作简单计算器App

计算机界面如图：

程序设计步骤：

(1)在布局文件中声明编辑文件框EditText，按钮Button等组件。

(2)在MainActivity中获取组件实例。

(3)通过swtich函数，判断输入的内容，并进行相应操作，通过getText()获取文本内容，setText()显示。

程序代码设计:

布局实现：在activi_main.xml中设置。使用线性布局(LinearLayout)与网格布局(GridLayout)来设置界面。在设计区域设置一个4行4列的网格布局，每行划分为均等的16个按钮，分别代表数字0-9，小数点，和运算符加减乘除以及等于号。

功能实现：在MainActivity.java页面编写。实现简单加减乘除。

package com.example.work_calculater;

import android.support.v7.app.AppCompatActivity;

import android.os.Bundle;

import android.view.View;

import android.widget.Button;

import android.widget.EditText;

public class MainActivity extends AppCompatActivity {

Button btn1; // 数字1

Button btn2; // 数字2

Button btn3; // 数字3

Button btn4; // 数字4

Button btn5; // 数字5

Button btn6; // 数字6

Button btn7; // 数字7

Button btn8; // 数字8

Button btn9; // 数字9

Button btn0; // 数字0

Button add; // +号

Button sub; // -号

Button mul; // *号

Button div; // 除号

Button dot; // 小数点

Button equ; // =号

Button clear; //清除

EditText result; // 显示文本

double num1 = 0, num2 = 0; //计算的数字

double Result = 0;//计算结果

int op = 0;//判断操作符

String opd = " ";//显示操作符

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

// 获取页面上的控件

btn1 = findViewById(R.id.btn_1);

btn2 = findViewById(R.id.btn_2);

btn3 = findViewById(R.id.btn_3);

btn4 = findViewById(R.id.btn_4);

btn5 = findViewById(R.id.btn_5);

btn6 = findViewById(R.id.btn_6);

btn7 = findViewById(R.id.btn_7);

btn8 = findViewById(R.id.btn_8);

btn9 = findViewById(R.id.btn_9);

btn0 = findViewById(R.id.btn_0);

add = findViewById(R.id.btn_add);

sub = findViewById(R.id.btn_sub);

mul = findViewById(R.id.btn_mul);

div = findViewById(R.id.btn_div);

equ = findViewById(R.id.btn_equ);

dot = findViewById(R.id.btn_dot);

clear = findViewById(R.id.btn_clear);

result = findViewById(R.id.et_result);

// 按钮的单击事件

btn1.setOnClickListener(new Click());

btn2.setOnClickListener(new Click());

btn3.setOnClickListener(new Click());

btn4.setOnClickListener(new Click());

btn5.setOnClickListener(new Click());

btn6.setOnClickListener(new Click());

btn7.setOnClickListener(new Click());

btn8.setOnClickListener(new Click());

btn9.setOnClickListener(new Click());

btn0.setOnClickListener(new Click());

add.setOnClickListener(new Click());

sub.setOnClickListener(new Click());

mul.setOnClickListener(new Click());

div.setOnClickListener(new Click());

equ.setOnClickListener(new Click());

dot.setOnClickListener(new Click());

clear.setOnClickListener(new Click());

result.setOnClickListener(new Click());

}

// 设置按钮点击后的监听

class Click implements View.OnClickListener {

public void onClick(View v) {

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

case R.id.btn_0: //获取，0-9、小数点，并在编辑框显示

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

myString += "0";

result.setText(myString);

break;

case R.id.btn_1:

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

myString1 += "1";

result.setText(myString1);

break;

case R.id.btn_2:

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

myString2 += "2";

result.setText(myString2);

break;

case R.id.btn_3:

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

myString3 += "3";

result.setText(myString3);

break;

case R.id.btn_4:

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

myString4 += "4";

result.setText(myString4);

break;

case R.id.btn_5:

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

myString5 += "5";

result.setText(myString5);

break;

case R.id.btn_6:

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

myString6 += "6";

result.setText(myString6);

break;

case R.id.btn_7:

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

myString7 += "7";

result.setText(myString7);

break;

case R.id.btn_8:

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

myString8 += "8";

result.setText(myString8);

break;

case R.id.btn_9:

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

myString9 += "9";

result.setText(myString9);

break;

case R.id.btn_dot:

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

myStringDot += ".";

result.setText(myStringDot);

break;

case R.id.btn_add: //判断，使用加减乘除的操作符

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

if (myStringAdd.equals(null)) {

return;

}

num1 = Double.valueOf(myStringAdd);

result.setText(null);

op = 1;

opd = "+";

break;

case R.id.btn_sub:

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

if (myStringSub.equals(null)) {

return;

}

num1 = Double.valueOf(myStringSub);

result.setText(null);

op = 2;

opd = "-";

break;

case R.id.btn_mul:

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

if (myStringMul.equals(null)) {

return;

}

num1 = Double.valueOf(myStringMul);

result.setText(null);

op = 3;

opd = "×";

break;

case R.id.btn_div:

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

if (myStringDiv.equals(null)) {

return;

}

num1 = Double.valueOf(myStringDiv);

result.setText(null);

op = 4;

opd = "÷";

break;

case R.id.btn_clear: //清除，将编辑框文本显示为空

result.setText(null);

break;

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

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

if (myStringEqu.equals(null)) {

return;

}

num2 = Double.valueOf(myStringEqu);

result.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;

}

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

break;

default:

break;

}

}

}

}

程序运行结果如图：