java.lang.NumberFormatException: For input string: ""怎么回事？

Question

java.lang.NumberFormatException: For input string: ""
at java.lang.NumberFormatException.forInputString(Unknown Source)
at java.lang.Integer.parseInt(Unknown Source)
at java.lang.Integer.parseInt(Unknown Source)
at action.SomebodyAction.execute(SomebodyAction.java:53)
at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:431)
at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:236)
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:432)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:710)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:230)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:104)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:261)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:581)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
at java.lang.Thread.run(Unknown Source)
2008-7-22 10:41:26 org.apache.struts.action.RequestProcessor processException
警告: Unhandled Exception thrown: class java.lang.NumberFormatException
2008-7-22 10:41:26 org.apache.catalina.core.StandardWrapperValve invoke
严重: Servlet.service() for servlet action threw exception
java.lang.NumberFormatException: For input string: ""
at java.lang.NumberFormatException.forInputString(Unknown Source)
at java.lang.Integer.parseInt(Unknown Source)
at java.lang.Integer.parseInt(Unknown Source)
at dco.SomebodyDCO.getAllUser(SomebodyDCO.java:78)
at action.SomebodyAction.execute(SomebodyAction.java:68)
at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:431)
at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:236)
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:432)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:710)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:230)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:104)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:261)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:581)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
at java.lang.Thread.run(Unknown Source)

Answer 1

public class SomebodyAction extends Action{
public ActionForward execute(ActionMapping mapping
 ,ActionForm form
 ,HttpServletRequest request
 ,HttpServletResponse response) throws Exception{

StringEncode se = new StringEncode();
    SomebodyDTO dto = new SomebodyDTO();
    System.out.println("......................");
    PageControl pageControl = new PageControl();
    SomebodyDCO projectListDCO = new SomebodyDCO();
    List projectList = new ArrayList();
SomebodyForm myForm = (SomebodyForm) form;

if(myForm.getInt_num()==null){
myForm.setInt_num(pageControl.getInt_num()+"");
}else{
try{
pageControl.setInt_num(Integer.parseInt(myForm.getInt_num().trim()));
}catch(Exception e)
{
e.printStackTrace();
}
}

myForm.setZhuanye(se.convertEncode(myForm.getZhuanye()));
myForm.setLike(se.convertEncode(myForm.getLike()));
    if(myForm.getCurpage()==null){
     myForm.setCurpage("1");
    }
    
    try {
    BeanUtils.copyProperties(dto,myForm);
    projectList = projectListDCO.getAllUser(dto,pageControl);
    }catch (SQLException ex) {
     ex.printStackTrace();
    }
    pageControl.init(Integer.parseInt(myForm.getCurpage()),projectListDCO.sumNote);
    request.setAttribute("pageBean",pageControl);
    myForm.setTotalpage(pageControl.getTotalnum());
    request.setAttribute("list",projectList);
   return mapping.findForward("success");
}
}

Answer 2

pageControl.setInt_num(Integer.parseInt(myForm.getInt_num().trim()));
这是53行

Answer 3

你在程序中要转的字符串不是一个数字,所以在format成数字的时候就出错了,检查下就是了

Answer 4

at action.SomebodyAction.execute(SomebodyAction.java:53) 
这个地方传入的参数不能进行Integer.parseInt转换
看看出入的内容是什么

Answer 5

NumberFormatException: For input string: "" 
你的这个字符串不符合数字预定格式。完毕

Answer 6

当你强制转换一个String为Integer时,而这个String为""时的异常,即你的String不能转为Integer的异常

Answer 7

public class SomebodyForm extends ActionForm{
private String name = null;
private int age = 0;
private String zhuanye = null;
private String like = null;
private String curpage = null;
private String int_num = null;
private int totalpage = 0;



/**
 * @return 返回 int_num。
 */
public String getInt_num() {
return int_num;
}
/**
 * @param int_num 要设置的 int_num。
 */
public void setInt_num(String int_num) {
this.int_num = int_num;
}
这里的问题？

Answer 8

java.lang.NumberFormatException: For input string: ""
at java.lang.NumberFormatException.forInputString(Unknown Source)
at java.lang.Integer.parseInt(Unknown Source)
at java.lang.Integer.parseInt(Unknown Source) 
看看什么地方调用　Integer.parseInt()了，参数有问题。

Answer 9

Integer.parseInt(myForm.getInt_num().trim())
你myForm.getInt_num().trim()这个字符串不是一个数字形式的
java.lang.NumberFormatException: For input string: "" 
它是一个空字符串
不能转换成int

Answer 10

你在执行下面这句之前
Integer.parseInt(myForm.getInt_num().trim()))
先输出一下
myForm.getInt_num().trim())
的内容，然后再找是哪里的错误。

Answer 11

at dco.SomebodyDCO.getAllUser(SomebodyDCO.java:78) 
at action.SomebodyAction.execute(SomebodyAction.java:68) 
看这两行吧  哪个对象是空的