由于一个完整的App代码涉及多个层面（如前端、后端、数据库等），并且不同 ...

• Swift (iOS App)gzjiazheng.cn
  Swift是Apple的官方编程语言，用于开发iOS和macOS应用。
  

swift
import UIKit
class ViewController: UIViewController {

1. override func viewDidLoad() {  
2.     super.viewDidLoad()  
3.     // Do any additional setup after loading the view.  
4. }  
6. @IBAction func buttonPressed(_ sender: Any) {  
7.     // 响应按钮点击事件  
8.     print("Button was pressed!")  
9. }  

复制代码

}
2. Java (Android App)
Java是Android开发的重要语言之一。
java
import android.os.Bundle;
import android.widget.Button;
import android.view.View;
import androidx.appcompat.app.AppCompatActivity;
public class MainActivity extends AppCompatActivity {

1. @Override  
2. protected void onCreate(Bundle savedInstanceState) {  
3.     super.onCreate(savedInstanceState);  
4.     setContentView(R.layout.activity_main);  
6.     Button button = findViewById(R.id.my_button);  
7.     button.setOnClickListener(new View.OnClickListener() {  
8.         @Override  
9.         public void onClick(View v) {  
10.             // 响应按钮点击事件  
11.             System.out.println("Button was pressed!");  
12.         }  
13.     });  
14. }  

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}
3. Flutter (跨平台App)
Flutter利用Dart语言进行开发。
Dart (Flutter)
dart
import ‘package:flutter/material.dart’;
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
title: ‘Flutter Demo’,
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: MyHomePage(title: ‘Flutter Demo Home Page’),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key? key, required this.title}) : super(key: key);
final String title;
@override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State {
int _counter = 0;
void _incrementCounter() {
setState(() {
_counter++;
});
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: [
Text(
‘You have pushed the button this many times:’,
),
Text(
‘$_counter’,
style: Theme.of(context).textTheme.headline4,
),
],
),
),
floatingActionButton: FloatingActionButton(
onPressed: _incrementCounter,
tooltip: ‘Increment’,
child: Icon(Icons.add),
), // This trailing comma makes auto-formatting nicer for Flutter code.
);
}
}
4. React Native (跨平台App)
React Native利用JavaScript和React进行开发。
JavaScript (React Native)
jsx
import React, { useState } from ‘react’;
import { View, Text, Button, StyleSheet } from ‘react-native’;
const App = () => {
const [count, setCount] = useState(0);
const onPress = () => {
setCount(count + 1);
};
return (

     You have pressed the button {count} times  


);
};
const styles = StyleSheet.create({
container: {
flex: 1,
justifyContent: ‘center’,
alignItems: ‘center’,
},
});
export default App;
这些示例只是App开发的一小部门由于一个完整的App代码涉及多个层面（如前端、后端、数据库等），并且不同的操作系统（如iOS、Android）和平台（如React Native、Flutter、Xamarin等）有不同的实现方式，因此在这里我将给出几种不同编程语言下创建App的简单示例或框架。

• Swift (iOS App)
  Swift是Apple的官方编程语言，用于开发iOS和macOS应用。
  

swift
import UIKit
class ViewController: UIViewController {

1. override func viewDidLoad() {  
2.     super.viewDidLoad()  
3.     // Do any additional setup after loading the view.  
4. }  
6. @IBAction func buttonPressed(_ sender: Any) {  
7.     // 响应按钮点击事件  
8.     print("Button was pressed!")  
9. }  

复制代码

}
2. Java (Android App)
Java是Android开发的重要语言之一。
java
import android.os.Bundle;
import android.widget.Button;
import android.view.View;
import androidx.appcompat.app.AppCompatActivity;
public class MainActivity extends AppCompatActivity {

1. @Override  
2. protected void onCreate(Bundle savedInstanceState) {  
3.     super.onCreate(savedInstanceState);  
4.     setContentView(R.layout.activity_main);  
6.     Button button = findViewById(R.id.my_button);  
7.     button.setOnClickListener(new View.OnClickListener() {  
8.         @Override  
9.         public void onClick(View v) {  
10.             // 响应按钮点击事件  
11.             System.out.println("Button was pressed!");  
12.         }  
13.     });  
14. }  

复制代码

}
3. Flutter (跨平台App)
Flutter利用Dart语言进行开发。
Dart (Flutter)
dart
import ‘package:flutter/material.dart’;
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
title: ‘Flutter Demo’,
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: MyHomePage(title: ‘Flutter Demo Home Page’),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key? key, required this.title}) : super(key: key);
final String title;
@override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State {
int _counter = 0;
void _incrementCounter() {
setState(() {
_counter++;
});
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: [
Text(
‘You have pushed the button this many times:’,
),
Text(
‘$_counter’,
style: Theme.of(context).textTheme.headline4,
),
],
),
),
floatingActionButton: FloatingActionButton(
onPressed: _incrementCounter,
tooltip: ‘Increment’,
child: Icon(Icons.add),
), // This trailing comma makes auto-formatting nicer for Flutter code.
);
}
}
4. React Native (跨平台App)
React Native利用JavaScript和React进行开发。
JavaScript (React Native)
jsx
import React, { useState } from ‘react’;
import { View, Text, Button, StyleSheet } from ‘react-native’;
const App = () => {
const [count, setCount] = useState(0);
const onPress = () => {
setCount(count + 1);
};
return (

     You have pressed the button {count} times  


);
};
const styles = StyleSheet.create({
container: {
flex: 1,
justifyContent: ‘center’,
alignItems: ‘center’,
},
});
export default App;
这些示例只是App开发的一小部门

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