Java/Maven无法编译简单代码

Question

这个非常简单的代码根本无法编译。我不是一个Java专业人员，但我很确定这是标准的东西，应该只是工作！

String fields = "a,b,c"; 
String[] fields_array = fields.split(','); 

不会编译

mvn test clean 

cannot find symbol symbol : method split(char) 
location: class java.lang.String 

的pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
     xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd"> 

    <modelVersion>4.0.0</modelVersion> 

    <groupId>com.example</groupId> 
    <artifactId>simple-service</artifactId> 
    <packaging>jar</packaging> 
    <version>1.0-SNAPSHOT</version> 
    <name>simple-service</name> 

    <dependencyManagement> 
     <dependencies> 
      <dependency> 
       <groupId>org.glassfish.jersey</groupId> 
       <artifactId>jersey-bom</artifactId> 
       <version>${jersey.version}</version> 
       <type>pom</type> 
       <scope>import</scope> 
      </dependency> 
     </dependencies> 
    </dependencyManagement> 

    <dependencies> 
     <dependency> 
      <groupId>org.glassfish.jersey.containers</groupId> 
      <artifactId>jersey-container-grizzly2-http</artifactId> 
     </dependency> 
     <dependency> 
      <groupId>org.glassfish.jersey.media</groupId> 
      <artifactId>jersey-media-moxy</artifactId> 
     </dependency> 
     <dependency> 
      <groupId>junit</groupId> 
      <artifactId>junit</artifactId> 
      <version>4.9</version> 
      <scope>test</scope> 
     </dependency> 
     <dependency> 
      <groupId>commons-lang</groupId> 
      <artifactId>commons-lang</artifactId> 
      <version>2.3</version> 
     </dependency> 
     <dependency> 
      <groupId>org.glassfish.jersey.core</groupId> 
      <artifactId>jersey-client</artifactId> 
      <scope>test</scope> 
     </dependency> 
     <dependency> 
      <groupId>de.abas.ceks</groupId> 
      <artifactId>jedp</artifactId> 
      <version>1.0</version> 
     </dependency> 
     <dependency> 
      <groupId>de.abas.jfop</groupId> 
      <artifactId>base</artifactId> 
      <version>1.0</version> 
     </dependency> 
     <dependency> 
      <groupId>de.abas.eks</groupId> 
      <artifactId>jfop</artifactId> 
      <version>1.0</version> 
     </dependency> 
     <dependency> 
      <groupId>de.abas.erp</groupId> 
      <artifactId>common</artifactId> 
      <version>1.0</version> 
     </dependency> 
     <dependency> 
      <groupId>net.sourceforge.javautil</groupId> 
      <artifactId>common</artifactId> 
      <version>0.0.5</version> 
      <scope>compile</scope> 
     </dependency> 
     <dependency> 
      <groupId>mysql</groupId> 
      <artifactId>mysql-connector-java</artifactId> 
      <version>5.1.6</version> 
     </dependency> 
    </dependencies> 

    <build> 
     <plugins> 
      <plugin> 
       <groupId>org.apache.maven.plugins</groupId> 
       <artifactId>maven-compiler-plugin</artifactId> 
       <version>2.5.1</version> 
       <!-- <inherited>true</inherited> --> 
       <configuration> 
        <source>1.6</source> 
        <target>1.6</target> 
       </configuration> 
      </plugin> 
      <plugin> 
       <groupId>org.codehaus.mojo</groupId> 
       <artifactId>exec-maven-plugin</artifactId> 
       <version>1.2.1</version> 
       <executions> 
        <execution> 
         <goals> 
          <goal>java</goal> 
         </goals> 
        </execution> 
       </executions> 
       <configuration> 
        <mainClass>com.example.Main</mainClass> 
       </configuration> 
      </plugin> 
     </plugins> 
    </build> 

    <repositories> 
     <repository> 
      <id>javautil</id> 
      <name>Java Util Repository</name> 
      <url>http://downloads.sourceforge.net/project/javautil/</url> 
     </repository> 
    </repositories> 

    <properties> 
     <jersey.version>2.2</jersey.version> 
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> 
    </properties> 
</project> 

进口

package com.example; 

import javax.ws.rs.GET; 
import javax.ws.rs.Path; 
import javax.ws.rs.Produces; 
import javax.ws.rs.core.MediaType; 
import javax.ws.rs.DefaultValue; 
import javax.ws.rs.QueryParam; 

import de.abas.ceks.jedp.*; 

import java.lang.String; 

Answer 1

String#split()方法接受一个字符串，并','是一个字符。字符串文字用双引号引起来。你应该使用：

String[] fields_array = fields.split(","); 

PS：你不需要从java.lang包中导入类。该软件包默认在所有Java源文件中导入。