小编Fah*_*nej的帖子

我正在从事 Spring Boot 项目。我的项目中有存储库文件，但它会在存储库类中显示一条警告消息Unnecessary @Repository。我正在JpaRepository<>用我的存储库扩展 a 。我的 Spring 版本是4，JDK 版本是17。

这是我的依赖项

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-devtools</artifactId>
    <scope>runtime</scope>
    <optional>true</optional>
</dependency>

<dependency>
    <groupId>com.mysql</groupId>
    <artifactId>mysql-connector-j</artifactId>
    <scope>runtime</scope>
</dependency>

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-test</artifactId>
    <scope>test</scope>
</dependency>

这是我的存储库

@Repository // Here I get a warning to remove this annotation becasue its unnecessary
public interface CollegeRepo extends JpaRepository<College, Integer>{
    
}

我Student使用 java 8 的自然排序方法迭代所有数据sorted()。迭代学生数据时，在 IDE 控制台中出现异常class com.java8.Student cannot be cast to class java.lang.Comparable。我的StreamStudent.java文件在com.java8包内。

这是我的完整堆栈跟踪：

Exception in thread "main" java.lang.ClassCastException: class com.java8.Student cannot be cast to class java.lang.Comparable (com.java8.Student is in unnamed module of loader 'app'; java.lang.Comparable is in module java.base of loader 'bootstrap')
    at java.base/java.util.Comparators$NaturalOrderComparator.compare(Comparators.java:47)
    at java.base/java.util.TimSort.countRunAndMakeAscending(TimSort.java:355)
    at java.base/java.util.TimSort.sort(TimSort.java:220)
    at java.base/java.util.Arrays.sort(Arrays.java:1307)
    at java.base/java.util.stream.SortedOps$SizedRefSortingSink.end(SortedOps.java:353)
    at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:510)
    at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:499)
    at java.base/java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:921)
    at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
    at java.base/java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:682)
    at com.java8.StreamStudent.main(StreamStudent.java:72)

下面是我的代码：

package com.java8;

import java.util.*; …

我收到错误：

数据截断：对于第 1 行的“配置文件”列来说数据太长

我存储的变量照片如下：

我的实体代码在这里：

实体：

@Entity
@Table(name = "profile_master")
public class profileEntity {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int p_id;
    private String profile;
    private String website;
    private String bio;
    private String gender;

    // getter setter

}