What are the causes of exceptions in java?

15/10/2008

A java exception can be thrown only in the following three scenarios:

(1) An abnormal execution condition was synchronously detected by the Java virtual machine.
- When evaluation of an expression violates the normal semantics (Example: an integer divide by zero)
- An error occurs in loading or linking part of the program
- When limitation on a resource is exceeded (Example: using too much memory)

(2) A throw statement was executed.

(3) An asynchronous exception occurred.
- The stop method (deprecated) of class Thread was invoked
- An internal error has occurred in the java virtual machine

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I was reading your articles last day[actually first time:-(]..
I have a query while working with StringTokenizer. Please see the code below and please let me know what is wrong in that and why it is throwing PatternSysntaxException? Is it wrong way to use?
class TestHashMap{
public TestHashMap(){
HashMap hMap=new HashMap();
hMap.put(“Name”, “Mahesh”);
hMap.put(“Age”, 26);
hMap.put(“Designation”, “Software Engineer”);
hMap.put(“Company”, “Logica”);
System.out.println(hMap);
String hMapString = hMap.toString();
hMapString = hMapString.replaceAll(“{“, “”);
StringTokenizer hMapStringTokens=new StringTokenizer(hMapString, “,”);
while(hMapStringTokens.hasMoreTokens()){
StringTokenizer keyValueTokens=new StringTokenizer(hMapStringTokens.nextToken(),”=”);
while(keyValueTokens.hasMoreTokens()){
System.out.println(“Token->”+keyValueTokens.nextToken());
}
}
}
}

Mahesh Kumawat on October 26th, 2010 5:10 am

Hi Mahesh,

try this

import java.util.HashMap;
import java.util.StringTokenizer;

class Test {
public Test() {
HashMap hMap = new HashMap();
hMap.put(“Name”, “Mahesh”);
hMap.put(“Age”, 26);
hMap.put(“Designation”, “Software Engineer”);
hMap.put(“Company”, “Logica”);
System.out.println(hMap);
String hMapString = hMap.toString();
hMapString = hMapString.replace(“{“,”");
hMapString = hMapString.replace(“}”,”");

StringTokenizer hMapStringTokens = new StringTokenizer(hMapString, “,”);
while (hMapStringTokens.hasMoreTokens()) {
StringTokenizer keyValueTokens = new StringTokenizer(
hMapStringTokens.nextToken(), “=”);
while (keyValueTokens.hasMoreTokens()) {
System.out.println(“Token->” + keyValueTokens.nextToken());
}
}
}

public static void main(String[] args){
new Test();
}

}

Output:

{Name=Mahesh, Age=26, Company=Logica, Designation=Software Engineer}
Token->Name
Token->Mahesh
Token-> Age
Token->26
Token-> Company
Token->Logica
Token-> Designation
Token->Software Engineer

Prashant Pandey on November 2nd, 2010 1:20 pm