Java例题

本文深入探讨了Java编程中的典型问题及解决方案,通过实例讲解了语言特性和常见算法的应用,旨在帮助读者提升Java编程技能。

摘要生成于 C知道 ,由 DeepSeek-R1 满血版支持, 前往体验 >

    在窗口的中心位置添加了一个选项窗格,该选项窗格里添加了一个网格布局面板和一个空布局面板。
public class Example9_4 {

	public static void main(String[] args) {
		new ShowLayout();
	}
}
import java.awt.*;
import javax.swing.*;
public class ShowLayout extends JFrame{
        PanelGridLayout pannelGrid;
        PanelNullLayout panelNull;
        JTabbedPane p;
        ShowLayout(){
        	pannelGrid = new PanelGridLayout();
        	panelNull = new PanelNullLayout();
        	p = new JTabbedPane();
        	p.add("网格布局的面板", pannelGrid);
        	p.add("空布局的面板",panelNull);
        	add(p,BorderLayout.CENTER);
        	add(new JButton("窗体是BorderLayout布局"),BorderLayout.NORTH);
        	add(new JButton("南"),BorderLayout.SOUTH);
        	add(new JButton("西"),BorderLayout.WEST);
        	add(new JButton("北"),BorderLayout.EAST);
        	setBounds(10,10,570,390);
        	setVisible(true);
        	setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
        	validate();
        }
}
import java.awt.*;
import javax.swing.*;
public class PanelGridLayout extends JPanel{
    PanelGridLayout(){
    	GridLayout grid = new GridLayout(12,12);
    	setLayout(grid);
    	Label label[][] = new Label[12][12];
    	for(int i=0;i<12;i++) {
    		for(int j=0;j<12;j++) {
    			label[i][j]=new Label();
    			if((i+j)%2==0) 
    				label[i][j].setBackground(Color.black);
    			else 
    				label[i][j].setBackground(Color.white);
    			add(label[i][j]);
    		}
    	}
    }
}
import javax.swing.*;
public class PanelNullLayout extends JPanel {
      JButton button;
      JTextField text;
      PanelNullLayout(){
    	  setLayout(null);
    	  button = new JButton("确定");
    	  text = new JTextField();
    	  add(text);
    	  text.setBounds(100,30,90,30);
    	  button.setBounds(190,30,66,30);
      }
}

运行结果:

### Java 程序设计例题 #### 面向对象编程 以下是一个 Java 面向对象编程的示例,展示如何定义类、继承和多态[^1]: ```java class Animal { String name; public Animal(String name) { this.name = name; } public void speak() { System.out.println(name + " makes a sound."); } } class Dog extends Animal { public Dog(String name) { super(name); } @Override public void speak() { System.out.println(name + " says Woof!"); } } class Cat extends Animal { public Cat(String name) { super(name); } @Override public void speak() { System.out.println(name + " says Meow!"); } } public class Main { public static void main(String[] args) { Animal dog = new Dog("Buddy"); Animal cat = new Cat("Kitty"); dog.speak(); // 输出: Buddy says Woof! cat.speak(); // 输出: Kitty says Meow! } } ``` --- #### 框架应用 以下是一个使用 Spring Framework 的示例,展示如何配置一个简单的 Bean 并注入依赖[^2]: ```java import org.springframework.context.annotation.AnnotationConfigApplicationContext; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; @Configuration class AppConfig { @Bean public Animal animal() { return new Dog("Buddy"); } } public class Main { public static void main(String[] args) { AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(AppConfig.class); Animal animal = context.getBean(Animal.class); animal.speak(); // 输出: Buddy says Woof! context.close(); } } ``` --- #### 数据库程序设计 以下是一个使用 JDBC 连接 MySQL 数据库并执行查询的示例[^4]: ```java import java.sql.Connection; import java.sql.DriverManager; import java.sql.PreparedStatement; import java.sql.ResultSet; public class DatabaseExample { public static void main(String[] args) { String url = "jdbc:mysql://localhost:3306/example_db"; String user = "root"; String password = "password"; try (Connection conn = DriverManager.getConnection(url, user, password)) { String query = "SELECT id, name FROM users"; PreparedStatement stmt = conn.prepareStatement(query); ResultSet rs = stmt.executeQuery(); while (rs.next()) { int id = rs.getInt("id"); String name = rs.getString("name"); System.out.println("ID: " + id + ", Name: " + name); } } catch (Exception e) { e.printStackTrace(); } } } ``` --- #### 移动应用开发 以下是一个使用 Android Studio 创建简单移动应用的示例[^5]: ```java import android.os.Bundle; import android.widget.TextView; import androidx.appcompat.app.AppCompatActivity; public class MainActivity extends AppCompatActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); TextView textView = new TextView(this); textView.setText("Hello, Android!"); setContentView(textView); } } ``` --- #### AI 辅助开发 以下是一个使用 Deeplearning4j 构建简单神经络的示例[^6]: ```java import org.deeplearning4j.nn.conf.NeuralNetConfiguration; import org.deeplearning4j.nn.conf.layers.DenseLayer; import org.deeplearning4j.nn.multilayer.MultiLayerNetwork; import org.nd4j.linalg.activations.Activation; import org.nd4j.linalg.learning.config.Adam; public class NeuralNetworkExample { public static void main(String[] args) { MultiLayerNetwork model = new MultiLayerNetwork(new NeuralNetConfiguration.Builder() .updater(new Adam(0.001)) .list() .layer(new DenseLayer.Builder() .nIn(100) .nOut(64) .activation(Activation.RELU) .build()) .layer(new DenseLayer.Builder() .nIn(64) .nOut(10) .activation(Activation.SOFTMAX) .build()) .build()); model.init(); System.out.println("Model initialized successfully."); } } ``` ---
评论
添加红包

请填写红包祝福语或标题

红包个数最小为10个

红包金额最低5元

当前余额3.43前往充值 >
需支付:10.00
成就一亿技术人!
领取后你会自动成为博主和红包主的粉丝 规则
hope_wisdom
发出的红包
实付
使用余额支付
点击重新获取
扫码支付
钱包余额 0

抵扣说明:

1.余额是钱包充值的虚拟货币,按照1:1的比例进行支付金额的抵扣。
2.余额无法直接购买下载,可以购买VIP、付费专栏及课程。

余额充值