默认构造函数无法处理隐式超级构造函数抛出的异常类型异常
[英]Default constructor cannot handle exception type Exception thrown by implicit super constructor
问题描述
I am trying to read from a txt file and display it to a JSP file.
我正在尝试从 txt 文件中读取并将其显示到 JSP 文件中。
The Bean class gets BufferedReader from the FileReaderz class. Bean 类从FileReaderz类获取BufferedReader 。 I create a Beanx object in jsp, but this is where I get stuck我在 jsp 中创建了一个Beanx对象，但这就是我卡住的地方
public class Beanx {
public OuterBlock[] outer=new OuterBlock[100];
public InnerBlock[] inner=new InnerBlock[100];
/*public List<String> token1 = new ArrayList<String>();
public List<String> token2 = new ArrayList<String>();*/
//String[] token1;
//String[] token2;
public void callFileReaderz()throws Exception{
FileReaderz fr=new FileReaderz();
BufferedReader br1=FileReaderz.br;
String[] token;
int i=0,j=0;
String line;
while((line=br1.readLine())!=null){
//System.out.println(line);
token=line.split("#");
//List<String> tokenList=Arrays.asList(token);
if(token.length==5){
OuterBlock outerObj=new OuterBlock(token[0],Integer.parseInt(token[1]),Integer.parseInt(token[2]),
Float.parseFloat(token[3]),Float.parseFloat(token[4]));
this.outer[i++]=outerObj;
//System.out.println(token[0]);
}
else{
InnerBlock innerObj = new InnerBlock(token[0],token[1],Integer.parseInt(token[2]),
Integer.parseInt(token[3]),Float.parseFloat(token[4]),Float.parseFloat(token[5]));
this.inner[j++]=innerObj;
}
}
br1.close();
}
public Beanx() throws Exception{
this.callFileReaderz();
}
}
public class FileReaderz {
public static BufferedReader br;
public static void main (String[] args)throws Exception {
// TODO Auto-generated method stub
//public FileReaderz() throws FileNotFoundException{
br=new BufferedReader(new FileReader("database1.txt"));
//System.out.println(br.readLine());
}
}
When I try this in JSP page,当我在 JSP 页面中尝试这个时，
I get the error:我收到错误：
org.apache.jasper.JasperException: Unable to compile class for JSP:
An error occurred at line: 15 in the jsp file: /dashBoard.jsp
Default constructor cannot handle exception type Exception thrown by implicit super constructor. Must define an explicit constructor
12: </head>
13:
14: <body>
15: <%! Beanx bean=new Beanx(); %>
16: <div class="table-title">
17: <h3>Projects In Repository</h3>
18: </div>
1 个解决方案
解决方案1
1 已采纳 2016-10-04 07:24:57
This is because the Beanx class constructor throws Exception and you are creating Beanx object in declaration tag without handling the exception.这是因为Beanx类构造函数抛出Exception而您正在声明标记中创建Beanx对象而不处理异常。
To resolve this issue just initialize the Beanx in declaration tag with null as below:要解决此问题，只需将声明标记中的 Beanx 初始化为null ，如下所示：
<%! Beanx bean =null; %>
And whenever you need to use this bean in scriptlet tag use the below code:每当您需要在 scriptlet 标记中使用此 bean 时，请使用以下代码：
<%
try{
bean=new Beanx();
}catch(Exception e){
//To do something
}
%>
This is same as in below java code:这与下面的java代码相同：
class Main extends HttpServlet{
Beanx bean =null;
protected void doGet(HttpServletRequest request, HttpServletResponse response){
try{
bean=new Beanx();
}catch(Exception e){
//To do something
}
}
}
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