Java中`void`和`Void`的区别和特性详解

public class Example {
    public static void main(String[] args) {
        // 调用一个 void 方法
        printHello();
    }

    // 定义一个 void 方法
    public static void printHello() {
        System.out.println("Hello, World!");
    }
}

import java.util.ArrayList;
import java.util.List;

public class VoidExample {
    public static void main(String[] args) {
        // 创建一个 List<Void>，但实际上我们不会真正存储 Void 实例
        List<Void> voidList = new ArrayList<>();
        
        // 尝试添加 null 到列表中
        voidList.add(null);
        
        // 打印列表
        for (Void v : voidList) {
            System.out.println(v);  // 输出: null
        }
    }
}

import java.util.function.Consumer;

public class VoidExample {
    public static void main(String[] args) {
        // 使用 Consumer<Void> 表示一个消费者，它接受一个 Void 类型的参数
        Consumer<Void> consumer = (v) -> {
            System.out.println("This is a consumer that takes no input.");
        };
        
        // 传递 null 作为 Void 类型的值
        consumer.accept(null);
    }
}

public class VoidExample {
    public static void main(String[] args) {
        // 获取 Void 的唯一实例
        Void aVoid = null;  // 或者 Void aVoid = Void.TYPE;
        
        // 打印 Void 实例
        System.out.println(aVoid);  // 输出: null
    }
}

import org.springframework.web.bind.annotation.DeleteMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class WarehouseController {

    private final IMmsWarehouseDetailedAppService iMmsWarehouseDetailedAppService;

    public WarehouseController(IMmsWarehouseDetailedAppService iMmsWarehouseDetailedAppService) {
        this.iMmsWarehouseDetailedAppService = iMmsWarehouseDetailedAppService;
    }

    @DeleteMapping("/deleteById/{detailId}")
    public R<Void> deleteById(@PathVariable Long detailId) {
        boolean success = iMmsWarehouseDetailedAppService.deleteById(detailId);
        return toAjax(success);
    }

    public static <T> R<T> toAjax(boolean success) {
        if (success) {
            return new R<>(200, "操作成功", null);
        } else {
            return new R<>(500, "操作失败", null);
        }
    }
}

// 自定义响应类
class R<T> {
    private int code;
    private String message;
    private T data;

    public R(int code, String message, T data) {
        this.code = code;
        this.message = message;
        this.data = data;
    }

    // Getter 和 Setter
    public int getCode() {
        return code;
    }

    public void setCode(int code) {
        this.code = code;
    }

    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }

    public T getData() {
        return data;
    }

    public void setData(T data) {
        this.data = data;
    }
}

package com.Thursday.one;
 
public class Variable {
 
	
	public static void speaker(){
		System.out.println("你好");
	}
	public static String Talk(){
		return "hello";
	}
	public static void main(String[] args) {
		speaker();
		Talk();
		String aString = Talk();
		System.out.println(aString);
	}
}