实现计算机的简单功能
1、显示页面jsj.xml
XML
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:background="#eee">
<TextView
android:layout_width="match_parent"
android:layout_height="80dp"
android:background="#42714A"
android:gravity="center_vertical"
android:text="Chapter03"
android:textColor="#fff"
android:textSize="25sp"/>
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="简单计算机"
android:gravity="center_horizontal"
android:textSize="20sp"
android:textColor="#000"/>
<TextView
android:id="@+id/tvresult"
android:layout_width="match_parent"
android:layout_height="180dp"
android:background="#fff"
android:layout_margin="5dp"
android:text="0"
android:textSize="40sp"
android:textStyle="bold"
android:textColor="#000"
android:gravity="bottom|right"/>
<GridLayout
android:layout_marginTop="20dp"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:columnCount="4">
<Button
android:id="@+id/btn_ce"
style="@style/MyTextStyle"
android:text="CE"
/>
<Button
android:id="@+id/btn_divide"
style="@style/MyTextStyle"
android:text="÷"
/>
<Button
android:id="@+id/btn_multiply"
style="@style/MyTextStyle"
android:text="x" />
<Button
android:id="@+id/btn_c"
style="@style/MyTextStyle"
android:text="C"
/>
<Button
android:id="@+id/btn_7"
style="@style/MyTextStyle"
android:text="7"
/>
<Button
android:id="@+id/btn_8"
style="@style/MyTextStyle"
android:text="8"
/>
<Button
android:id="@+id/btn_9"
style="@style/MyTextStyle"
android:text="9"
/>
<Button
android:id="@+id/btn_plus"
style="@style/MyTextStyle"
android:text="+"
/>
<Button
android:id="@+id/btn_4"
style="@style/MyTextStyle"
android:text="4"
/>
<Button
android:id="@+id/btn_5"
style="@style/MyTextStyle"
android:text="5"
/>
<Button
android:id="@+id/btn_6"
style="@style/MyTextStyle"
android:text="6"
/>
<Button
android:id="@+id/btn_minus"
style="@style/MyTextStyle"
android:text="---"
/>
<Button
android:id="@+id/btn_1"
style="@style/MyTextStyle"
android:text="1"
/>
<Button
android:id="@+id/btn_2"
style="@style/MyTextStyle"
android:text="2"
/>
<Button
android:id="@+id/btn_3"
style="@style/MyTextStyle"
android:text="3"
/>
<Button
android:id="@+id/btn_sqrt"
style="@style/MyTextStyle"
android:text="√"
/>
<Button
android:id="@+id/btn_reciprocal"
style="@style/MyTextStyle"
android:text="1/X"
/>
<Button
android:id="@+id/btn_0"
style="@style/MyTextStyle"
android:text="0" />
<Button
android:id="@+id/btn_dot"
style="@style/MyTextStyle"
android:text="."
/>
<Button
android:id="@+id/btn_equal"
style="@style/MyTextStyle"
android:text="="
/>
</GridLayout>
</LinearLayout>2、样式页面 style.xml
XML
<?xml version="1.0" encoding="utf-8"?>
<resources>
<style name="MyTextStyle">
<item name="android:textSize">23sp</item>
<item name="android:layout_width">0dp</item>
<item name="android:layout_height">80dp</item>
<item name="android:layout_columnWeight">1</item>
</style>
</resources>3、后端代码CalculatorActivity.java
java
package com.example.android;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import androidx.appcompat.app.AppCompatActivity;
import java.text.DecimalFormat;
public class CalculatorActivity extends AppCompatActivity {
private TextView tvResult; //用于显示计算结果和输入表达式的控件
private String currentInput = "0"; //初始值为0
private String operator = ""; //当前选择的运算符，初始为空字符串
private double firstNumber = 0; //存储第一个操作数，初始值为0
private boolean isNewNumber = true; //标记是否开始输入新的数字，初始为true
@Override //活动创建时调用的方法
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.jsj); //活动布局界面
tvResult = findViewById(R.id.tvresult); //获取对象
int[] buttonIds = {
R.id.btn_ce, R.id.btn_divide, R.id.btn_multiply, R.id.btn_c,
R.id.btn_7, R.id.btn_8, R.id.btn_9, R.id.btn_plus,
R.id.btn_4, R.id.btn_5, R.id.btn_6, R.id.btn_minus,
R.id.btn_1, R.id.btn_2, R.id.btn_3, R.id.btn_sqrt,
R.id.btn_reciprocal, R.id.btn_0, R.id.btn_dot, R.id.btn_equal
}; //存储所有按钮的id
for (int id : buttonIds) { //为每个按钮设置点击事件监听器
Button button = findViewById(id);
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
handleButtonClick(((Button) v).getText().toString()); //调用handleButtonClick方法
}
});
}
}
private void handleButtonClick(String buttonText) {
switch (buttonText) {
case "CE":
currentInput = "0";
break;
case "C":
currentInput = "0";
operator = "";
firstNumber = 0;
isNewNumber = true;
break; //恢复初始状态
case "÷":
case "x":
case "+":
case "---":
if (!operator.isEmpty()) {
calculateResult(); //如果存在运算符，调用calculateResult方法
}
operator = buttonText;
firstNumber = Double.parseDouble(currentInput);
isNewNumber = true;
break;
case "=": //调用calculateResult方法计算结果，清空operator
calculateResult();
operator = "";
isNewNumber = true;
break;
case "√":
double sqrtResult = Math.sqrt(Double.parseDouble(currentInput));
currentInput = formatResult(sqrtResult);
break;
case "1/X":
if (!currentInput.equals("0")) { //分母不能为0
double reciprocalResult = 1 / Double.parseDouble(currentInput);
currentInput = formatResult(reciprocalResult);
} else {
currentInput = "错误";
}
break;
case ".":
if (isNewNumber) { //如果是新数字，currentInput设置为0
currentInput = "0.";
isNewNumber = false;
} else if (!currentInput.contains(".")) {
currentInput += "."; //如果不包含.则在后面追加.
}
break;
default:
if (isNewNumber) {
currentInput = buttonText;
isNewNumber = false;
} else {
currentInput += buttonText;
}
break;
}
tvResult.setText(currentInput); //将值设置到tvResult中显示
}
private void calculateResult() {
double secondNumber = Double.parseDouble(currentInput); //将输入内容转换成double型
double result = 0;
switch (operator) {
case "÷":
if (secondNumber != 0) { //如果除数不为0
result = firstNumber / secondNumber;
} else {
currentInput = "错误";
return;
}
break;
case "x":
result = firstNumber * secondNumber;
break;
case "+":
result = firstNumber + secondNumber;
break;
case "---":
result = firstNumber - secondNumber;
break;
}
currentInput = formatResult(result); //将结果赋值给currentInput
}
private String formatResult(double result) { //格式化
DecimalFormat decimalFormat = new DecimalFormat("#.########");
return decimalFormat.format(result);
}
}