如何从java中的列表中返回变量并将其输入MySQL数据库?

如何从java中的列表中返回变量并将其输入MySQL数据库?,java,mysql,list,arraylist,return,Java,Mysql,List,Arraylist,Return,我想返回所有的arraylist,但只有一个被返回,不明白为什么会发生这样的事情?花了一整天的时间试图理解这样错误的原因 Code : - import java.io.FileReader; import java.util.ArrayList; import java.util.Arrays; import java.util.List; import au.com.bytecode.opencsv.CSVReader; public class CSVFil

我想返回所有的arraylist,但只有一个被返回,不明白为什么会发生这样的事情?花了一整天的时间试图理解这样错误的原因

Code : -
  import java.io.FileReader;   
  import java.util.ArrayList; 
  import java.util.Arrays;
  import java.util.List;
  import au.com.bytecode.opencsv.CSVReader;


public class CSVFileReader {

   public List<String> main() {

    String startFile = "/Users/sample.csv";

    List<List<String>> build = new ArrayList<List<String>>();

        List<String> tempArr = null;

    try {
        CSVReader reader = new CSVReader(new FileReader(startFile));
        String[] line = null;

        String[] headers = reader.readNext();


        // generate headers
        for(String header : headers){
            tempArr = new ArrayList<String>();
           // tempArr.add(header);
            build.add(tempArr);
        }
        // generate content
        while((line = reader.readNext())!=null){
            for (int i = 0; i < build.size(); i++) {
                tempArr = build.get(i);
                String val = line[i];
                tempArr.add(val);
                //System.out.println("the value of the array variable is :"+val);
                build.set(i, tempArr);
            }
        }

         for(List<String> string:build){

             System.out.println("The value of the array and their variables are :"+string);

         }
         for (int i=0; i<build.size();){
               System.out.println("Element :"+build.get(i));
               return build.get(i);
            }

    } catch (Exception e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    return null;
}

public static void main(String[] args){
    CSVFileReader csvfilereader = new CSVFileReader();
    System.out.println("the returned variable is :"+csvfilereader.main());
    }
}

The CSV file is like:(Could Be A file of any size and any number of columns)
Keyword,AlternateKeyword,PrintValue
ego kit1,silicone baby dolls for sale,samsung
ego kit2,ego ce4,samsung
ego kit3,venus,samsung,
ego kit4,zz cream,samsung
ego kit5,samsung galaxy 7.7 case,samsung
ego kit6,apple,samsung

 And the Output is :

The value of the array and their variables are :[ego kit, ego kit, ego kit, ego kit, ego kit, ego kit]
The value of the array and their variables are :[silicone baby dolls for sale, ego ce4, venus, zz cream, samsung galaxy 7.7 case, apple]
The value of the array and their variables are :[Samsung, Samsung, Samsung, Samsung, Samsung, Samsung]
Element :[ego kit1, ego kit2, ego kit3, ego kit4, ego kit5, ego kit6]
the returned variable is :[ego kit, ego kit, ego kit, ego kit, ego kit, ego kit]
代码:-
导入java.io.FileReader;
导入java.util.ArrayList;
导入java.util.array;
导入java.util.List;
导入au.com.bytecode.opencsv.CSVReader;
公共类CSVFileReader{
公共列表main(){
字符串startFile=“/Users/sample.csv”;
列表生成=新建ArrayList();
列表tempArr=null;
试一试{
CSVReader reader=newcsvreader(newfilereader(startFile));
字符串[]行=null;
String[]headers=reader.readNext();
//生成标题
for(字符串标题:标题){
tempArr=newarraylist();
//tempArr.add(标题);
build.add(tempArr);
}
//生成内容
而((line=reader.readNext())!=null){
对于(int i=0;i
我不想要mysql条目的步骤,只想基于上面的元素创建Sql语句

Java新手,在这一点上卡住了,请帮助

for (int i=0; i<build.size();){
               System.out.println("Element :"+build.get(i));
               return build.get(i);
}
并返回
生成
列表,如下所示:

for (int i=0; i<build.size();){
               System.out.println("Element :"+build.get(i));
               //return build.get(i);
}
return build;

用于(int i=0;i您正在从
main
返回
tempArr
,而不是
build
,我假设这会更改方法签名…然后也是同样的错误,没有返回所有的arraylist,奇怪的是不明白为什么?您使用i作为构建器中的索引和行?我看起来很奇怪…您输出了什么佩克?对不起,我没收到it@isnot2bad,如果可能的话,请帮助我指出错误。我会从中吸取教训…这不会返回ArrayList并进入无限循环,只有在尝试了所有选项后,我才请求帮助。谢谢你的建议。
for (int i=0; i<build.size();){
               System.out.println("Element :"+build.get(i));
               //return build.get(i);
}
return build;