【问题】

I want to join or you can say union two csv file in other output .csv file, e.g. let say I have a csv file with fields a,b,c,d,e another with fields a,b,c,x,y,z I need output as in output file - a,b,c,d,e,x,y,z

I did as under but not getting desired output,Please let me know working java code

int n1 = 3,n2 = 3;//stores the serial number of the column that has the duplicate data

BufferedReader br1=new  BufferedReader(new  InputStreamReader(new  FileInputStream("c:/test/report1.csv")));

BufferedReader br2=new  BufferedReader(new  InputStreamReader(new  FileInputStream("c:/test/report2.csv")));

String line1,line2;

while((line1=br1.readLine())!=null && (line2=br2.readLine())!=null){

 String line=line1+","+line2;

 String newL="";

 StringTokenizer st=new  StringTokenizer(line,",");

 System.out.println("total tokens "+st.countTokens());

 int i = 3;

 for(int i=1;i<=st.countTokens();i++){

 if((i==n1)||(i==n1+n2))

 continue;

 else

 newL=newL+","+st.nextToken();

 }

 String l=newL.substring(1);

 System.out.println("merged "+l); 
//write this line to the output file

}

【回答】

以记录序号为标准合并结构化文件，JAVA 缺乏结构化计算类库，实现起来难免困难。这种情况下可用集算器辅助 JAVA 实现，SPL 代码如下：

A1-A2：分别读取 CSV 数据

A3：按记录序号合并文件，取出所需字段。

A4：将结果输出到 result.csv 中。

除了按序号合并，更常见的是按照某几个字段进行合并（类似 SQL 中的 join 语句），请参考【结构化文本计算示例】。

集算器不仅可以进行关联计算，还可以通过 JDBC 与 JAVA 集成，参考《Java 如何调用 SPL 脚本》。