"error: cannot find symbol“使用Apache POI

Question

这是我的代码：

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.*;

import org.apache.poi.xssf.usermodel.XSSFCell;
import org.apache.poi.xssf.usermodel.XSSFRow;
import org.apache.poi.xssf.usermodel.XSSFSheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;


public class Reader {

    public static void read_excel() {

        File excel =  new File ("C:\\Users\\Username\\Desktop\\java-Tools\\data.xlsx");
        FileInputStream fis = new FileInputStream(excel);
        XSSFWorkbook wb = new XSSFWorkbook(fis);
}

这将导致以下错误消息：

error: cannot find symbol 
File excel =  new File ("C:\\Users\\Username\\Desktop\\java-Tools\\data.xlsx");
symbol: class File
location: class reader

我已经为Apache POI库的jar文件设置了CLASSPATH。下面是CLASSPATH变量的内容：

.;C:\Users\Username\Desktop\Code\Classes;C:\poi-3.12\poi-3.12-20150511.jar;C:\poi-3.12\poi-ooxml-3.12-20150511.jar;C:\poi-3.12\poi-ooxml-schemas-3.12-20150511.jar;C:\poi-3.12\ooxml-lib\xmlbeans-2.6.0.jar;C:\poi-3.12\lib\commons-codec-1.9.jar;C:\poi-3.12\lib\commons-logging-1.1.3.jar;C:\poi-3.12\lib\junit-4.12.jar; C:\poi-3.12\lib\log4j-1.2.17.jar;C:\poi-3.12\poi-examples-3.12-20150511.jar;C:\poi-3.12\poi-excelant-3.12-20150511.jar;C:\poi-3.12\poi-scratchpad-3.12-20150511.jar

我不明白为什么程序不能编译！

Answer 1

为文件添加导入语句

import java.io.File;

Answer 2

尝试使用以下代码

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.*;
import java.io.File;

import org.apache.poi.xssf.usermodel.XSSFCell;
import org.apache.poi.xssf.usermodel.XSSFRow;
import org.apache.poi.xssf.usermodel.XSSFSheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
public class Reader {

    public static void read_excel() throws FileNotFoundException {

        File excel =  new File ("C:\\Users\\Username\\Desktop\\java-Tools\\data.xlsx");
        FileInputStream fis = new FileInputStream(excel);
        XSSFWorkbook wb = new XSSFWorkbook(fis);
}

Answer 3

好了，下面的代码最终没有产生错误消息：

import java.io.FileInputStream;
import java.io.IOException;
import java.io.FileNotFoundException;
import java.io.InputStream;
import java.io.File;
import java.util.*;

import org.apache.poi.xssf.usermodel.XSSFCell;
import org.apache.poi.xssf.usermodel.XSSFRow;
import org.apache.poi.xssf.usermodel.XSSFSheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;





public class Reader {

    public static void read_excel()  throws FileNotFoundException, IOException {

        File excel =  new File ("C:\\Users\\Username\\Desktop\\java-Tools\\data.xlsx");
        FileInputStream fis = new FileInputStream(excel);
        XSSFWorkbook wb = new XSSFWorkbook(fis);
}