Android简易计算器实现功能附源码

在Android中实现计算功能是比较基础的，很多刚入门的Android开发人员都可以自主动手尝试一下。

效果如图：

activity_main.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:gravity="clip_horizontal"
 
   
 android:orientation="vertical"
 
   
 android:padding="30dp">
 
   
 
 
   
 <LinearLayout
 
   
 android:layout_width="match_parent"
 
   
 android:layout_height="wrap_content">
 
   
 
 
   
 <TextView
 
   
 android:layout_width="wrap_content"
 
   
 android:layout_height="wrap_content"
 
   
 android:layout_weight="1"
 
   
 android:text="操作数:"
 
   
 android:textSize="20sp" />
 
   
 
 
   
 <EditText
 
   
 android:id="@+id/firstNum"
 
   
 android:layout_width="wrap_content"
 
   
 android:layout_height="wrap_content"
 
   
 android:layout_weight="1"
 
   
 android:hint="请输入数值操作数"
 
   
 android:textStyle="bold"
 
   
 android:inputType="number" />
 
   
 </LinearLayout>
 
   
 
 
   
 <LinearLayout
 
   
 android:layout_width="match_parent"
 
   
 android:layout_height="wrap_content">
 
   
 
 
   
 <TextView
 
   
 android:layout_width="wrap_content"
 
   
 android:layout_height="wrap_content"
 
   
 android:layout_weight="1"
 
   
 android:text="算术运算:"
 
   
 android:textSize="20sp">
 
   
 
 
   
 </TextView>
 
   
 
 
   
 <Spinner
 
   
 android:id="@+id/operator"
 
   
 android:layout_width="wrap_content"
 
   
 android:layout_height="wrap_content"
 
   
 android:layout_weight="1"
 
   
 android:entries="@array/sign" />
 
   
 </LinearLayout>
 
   
 
 
   
 <LinearLayout
 
   
 android:layout_width="match_parent"
 
   
 android:layout_height="wrap_content">
 
   
 
 
   
 <TextView
 
   
 android:layout_width="wrap_content"
 
   
 android:layout_height="wrap_content"
 
   
 android:layout_weight="1"
 
   
 android:text="操作数:"
 
   
 android:textSize="20sp" />
 
   
 
 
   
 <EditText
 
   
 android:id="@+id/secondNum"
 
   
 android:layout_width="wrap_content"
 
   
 android:layout_height="wrap_content"
 
   
 android:layout_weight="1"
 
   
 android:hint="请输入数值操作数"
 
   
 android:textStyle="bold"
 
   
 android:inputType="number" />
 
   
 </LinearLayout>
 
   
 
 
   
 <LinearLayout
 
   
 android:layout_width="match_parent"
 
   
 android:layout_height="wrap_content">
 
   
 
 
   
 <Button
 
   
 android:id="@+id/calc"
 
   
 android:layout_width="wrap_content"
 
   
 android:layout_height="wrap_content"
 
   
 android:layout_weight="1"
 
   
 android:text="等于：" />
 
   
 
 
   
 <TextView
 
   
 android:id="@+id/result"
 
   
 android:layout_width="wrap_content"
 
   
 android:layout_height="wrap_content"
 
   
 android:layout_weight="5"
 
   
 android:hint="计算结果"
 
   
 android:padding="15dp"
 
   
 android:textColor="#F44336"
 
   
 android:textSize="25sp"
 
   
 android:textStyle="bold" />
 
   
 </LinearLayout>
 
   
</LinearLayout>
 
  

arrays.xml

  
  
 
   
<?xml version="1.0" encoding="utf-8"?>
 
   
<resources>
 
   
 <string-array name="sign">
 
   
 <item>请选择运算符</item>
 
   
 <item>+</item>
 
   
 <item>-</item>
 
   
 <item>*</item>
 
   
 <item>/</item>
 
   
 </string-array>
 
   
</resources>
 
  

MainActivity

  
  
 
   
package com.jld.homework;
 
   
 
 
   
import android.os.Bundle;
 
   
import android.view.View;
 
   
import android.widget.AdapterView;
 
   
import android.widget.Button;
 
   
import android.widget.EditText;
 
   
import android.widget.Spinner;
 
   
import android.widget.TextView;
 
   
 
 
   
import androidx.appcompat.app.AppCompatActivity;
 
   
 
 
   
public class MainActivity extends AppCompatActivity {
 
   
 String op;
 
   
 
 
   
 @Override
 
   
 protected void onCreate(Bundle savedInstanceState) {
 
   
 super.onCreate(savedInstanceState);
 
   
 setContentView(R.layout.activity_main);
 
   
 
 
   
 Spinner spinner = (Spinner) this.findViewById(R.id.operator);//获取活动布局中的Spinner对象
 
   
 //为Spinner注册内部监听器对象
 
   
 spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
 
   
 @Override
 
   
 public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
 
   
 //将Spinner选项的值赋值给成员变量op（保存算术运算符）
 
   
 op = ((TextView) view).getText().toString();
 
   
 }
 
   
 @Override
 
   
 public void onNothingSelected(AdapterView<?> parent) {
 
   
 }
 
   
 });
 
   
 
 
   
 //各类组件
 
   
 Button calcButton = findViewById(R.id.calc);
 
   
 EditText firstNum = findViewById(R.id.firstNum);
 
   
 EditText secondNum = findViewById(R.id.secondNum);
 
   
 TextView result = findViewById(R.id.result);
 
   
 
 
   
 //计算核心
 
   
 calcButton.setOnClickListener(v -> {
 
   
 switch (op) {
 
   
 case "+": {
 
   
 double r = Double.parseDouble(firstNum.getText().toString()) + Double.parseDouble(secondNum.getText().toString());
 
   
 result.setText(String.valueOf(r));
 
   
 break;
 
   
 }
 
   
 case "-": {
 
   
 double r = Double.parseDouble(firstNum.getText().toString()) - Double.parseDouble(secondNum.getText().toString());
 
   
 result.setText(String.valueOf(r));
 
   
 break;
 
   
 }
 
   
 case "*": {
 
   
 double r = Double.parseDouble(firstNum.getText().toString()) * Double.parseDouble(secondNum.getText().toString());
 
   
 result.setText(String.valueOf(r));
 
   
 break;
 
   
 }
 
   
 case "/": {
 
   
 double r = Double.parseDouble(firstNum.getText().toString()) / Double.parseDouble(secondNum.getText().toString());
 
   
 result.setText(String.valueOf(r));
 
   
 break;
 
   
 }
 
   
 default://非法情况报错
 
   
 result.setText(R.string.ERROR);
 
   
 break;
 
   
 }
 
   
 });
 
   
 }
 
   
}
 
  

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