1. Java (用于Android开发)szchuantian.com
   java
   public class MainActivity extends AppCompatActivity {

   @Override
   protected void onCreate(Bundle savedInstanceState) {
   super.onCreate(savedInstanceState);
   setContentView(R.layout.activity_main);

    // 在这里添加你的代码  
   

   }
   }

2. Swift (用于iOS开发)
   swift
   import UIKit

class ViewController: UIViewController {

override func viewDidLoad() {  
    super.viewDidLoad()  
    // Do any additional setup after loading the view.  
      
    // 在这里添加你的代码  
}  

}
3. Python (使用Kivy库进行跨平台开发)
python
from kivy.app import App
from kivy.uix.button import Button

class TestApp(App):
def build(self):
return Button(text=‘Hello World’)

if name == ‘main’:
TestApp().run()
4. React Native (JavaScript)
首先，你需要安装React Native CLI并创建一个新项目。但以下是一个简单的组件示例：

jsx
import React from ‘react’;
import { View, Text, Button } from ‘react-native’;

export default function App() {
return (

Hello, World!


);
}
5. Flutter (Dart)
Flutter使用Dart语言进行开发。以下是一个简单的Flutter应用示例：

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),
),
);
}
}
这些示例展示了如何开始使用不同的编程语言和技术栈来创建App。但是，为了完整地开发一个App，你还需要学习更多的内容，如UI设计、数据存储、网络请求等。由于直接为所有电脑语言编写一个完整的App代码是不切实际的（因为每种语言都有其特定的用途和平台），我将为您提供几个主流编程语言中用于创建App的基本框架或示例代码。请注意，这些示例可能不会直接运行，而是展示了如何开始使用这些语言进行App开发。

1. Java (用于Android开发)
   java
   public class MainActivity extends AppCompatActivity {

   @Override
   protected void onCreate(Bundle savedInstanceState) {
   super.onCreate(savedInstanceState);
   setContentView(R.layout.activity_main);

    // 在这里添加你的代码  
   

   }
   }

2. Swift (用于iOS开发)
   swift
   import UIKit

class ViewController: UIViewController {

override func viewDidLoad() {  
    super.viewDidLoad()  
    // Do any additional setup after loading the view.  
      
    // 在这里添加你的代码  
}  

}
3. Python (使用Kivy库进行跨平台开发)
python
from kivy.app import App
from kivy.uix.button import Button

class TestApp(App):
def build(self):
return Button(text=‘Hello World’)

if name == ‘main’:
TestApp().run()
4. React Native (JavaScript)
首先，你需要安装React Native CLI并创建一个新项目。但以下是一个简单的组件示例：

jsx
import React from ‘react’;
import { View, Text, Button } from ‘react-native’;

export default function App() {
return (

Hello, World!


);
}
5. Flutter (Dart)
Flutter使用Dart语言进行开发。以下是一个简单的Flutter应用示例：

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),
),
);
}
}
这些示例展示了如何开始使用不同的编程语言和技术栈来创建App。但是，为了完整地开发一个App，你还需要学习更多的内容，如UI设计、数据存储、网络请求等。