package database_wenjian;public class Wmain { /**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub Write write=new Write();
Inwrite inwrite=new Inwrite();
write.wdatabase();
write.adds(write.M, write.s);
System.out.println("It's work!01");
inwrite.Inwrite("E:\\database.txt", write.s);
System.out.println("It's work!02");
}}
package database_wenjian;import java.io.*;public class Inwrite{
public void Inwrite(String url,String[] s) {
try {
PrintWriter p=new PrintWriter(url);
for(int i=0;i<s.length;i++){//错误提示时就检查到这了
String as=s[i];
p.write(as);
p.println(0);
as="";
}
p.close();
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
Exception in thread "main" java.lang.NullPointerException
at database_wenjian.Inwrite.Inwrite(Inwrite.java:9)
at database_wenjian.Wmain.main(Wmain.java:16)
Exception in thread "main" java.lang.NullPointerException
at database_wenjian.Write.adds(Write.java:44)
at database_wenjian.Wmain.main(Wmain.java:14)
debug检查,数组s中值是null;错误就在这
public void adds(ArrayList M ,String[] s){
for(int i=1;i<=M.size();i++){
Company com=new Company();
com=(Company) M.get(i);
String aas=com.id+""+com.n+""+com.b+""+com.a;
s[i]=aas;
}
s[i]=aas;
这一句,我原本是想把com对象放到ArrayList数组中;但是读数据库中的值(我全部设的Varchar类型),不知道为什吗不能传到S[i]中
还是不行,是同一个错误:
Exception in thread "main" java.lang.NullPointerException
at database_wenjian.Write.adds(Write.java:44)
at database_wenjian.Wmain.main(Wmain.java:15)
值全部是null;