Java/JSP/Exception
Версия от 18:01, 31 мая 2010; (обсуждение)
Содержание
Calling Superclass Constructors
<HTML>
<HEAD>
<TITLE>Calling Superclass Constructors</TITLE>
</HEAD>
<BODY>
<H1>Calling Superclass Constructors</H1>
<%!
javax.servlet.jsp.JspWriter localOut;
class a
{
a() throws java.io.IOException
{
localOut.println("In a\"s constructor...<BR>");
}
}
class b extends a
{
b() throws java.io.IOException
{
localOut.println("In b\"s constructor...<BR>");
}
}
%>
<%
localOut = out;
b obj = new b();
%>
</BODY>
</HTML>
Catching an ArrayIndexOutOfBoundsException Exception
<HTML>
<HEAD>
<TITLE>Catching an ArrayIndexOutOfBoundsException Exception</TITLE>
</HEAD>
<BODY>
<H1>Catching an ArrayIndexOutOfBoundsException Exception</H1>
<%
try {
int array[] = new int[10];
array[100] = 100;
} catch (ArrayIndexOutOfBoundsException e) {
out.println("Array index out of bounds.");
}
%>
</BODY>
</HTML>
Causing a Runtime Error
<HTML>
<HEAD>
<TITLE>Causing a Runtime Error</TITLE>
</HEAD>
<BODY>
<H1>Causing a Runtime Error</H1>
<%
int i = 1;
i = i / 0;
out.println("The answer is " + i);
%>
</BODY>
</HTML>
Creating a Custom Exception Object
<HTML>
<HEAD>
<TITLE>Creating a Custom Exception Object</TITLE>
</HEAD>
<BODY>
<H1>Creating a Custom Exception Object</H1>
<%!
class NewException extends Exception
{
int value;
public String toString()
{
return "NewException " + value;
}
NewException(int v)
{
value = v;
}
}
void doWork(int value) throws NewException
{
if(value == 0){
throw new NewException(value);
}
}
%>
<%
try {
doWork(3);
doWork(0);
} catch (NewException e) {
out.println("Exception: " + e);
}
%>
</BODY>
</HTML>
Runtime Polymorphism
<HTML>
<HEAD>
<TITLE>Runtime Polymorphism</TITLE>
</HEAD>
<BODY>
<H1>Runtime Polymorphism</H1>
<%!
javax.servlet.jsp.JspWriter localOut;
class a
{
public void print() throws java.io.IOException
{
localOut.println("Hello from a...<BR>");
}
}
class b extends a
{
public void print() throws java.io.IOException
{
localOut.println("Hello from b...<BR>");
}
}
class c extends a
{
public void print() throws java.io.IOException
{
localOut.println("Hello from c...<BR>");
}
}
class d extends a
{
public void print() throws java.io.IOException
{
localOut.println("Hello from d...<BR>");
}
}
%>
<%
localOut = out;
a a1 = new a();
b b1 = new b();
c c1 = new c();
d d1 = new d();
a baseClassVariable;
baseClassVariable = a1;
baseClassVariable.print();
baseClassVariable = b1;
baseClassVariable.print();
baseClassVariable = c1;
baseClassVariable.print();
baseClassVariable = d1;
baseClassVariable.print();
%>
</BODY>
</HTML>
