关于异常
import *;import java.util.Vector;
public class ListOfNumbers {
private Vector<Integer> victor;
private static final int SIZE = 10;
public ListOfNumbers () {
victor = new Vector<Integer>(SIZE);
for (int i = 0; i < SIZE; i++)
victor.addElement(new Integer(i));//改i-2出现负数异常
}
public void writeList() {
PrintWriter out = null;
try {
System.out.println("Entering try statement");
out = new PrintWriter(new FileWriter("OutFile.txt"));
for (int i = 0; i < SIZE; i++)
out.println("Value at: " + i + " = " + victor.elementAt(i));//改i-2负数异常
}
catch (ArrayIndexOutOfBoundsException e) {
System.err.println("Caught ArrayIndexOutOfBoundsException: " +
e.getMessage());
}
catch (IOException e) {
System.err.println("Caught IOException: " + e.getMessage());
}
catch(NegativeArraySizeException e ){
System.err.println("Caught NegativeArraySizeException :"+e.getMessage());
}
catch(NullPointerException e){
System.err.println("Caught NullPointerException :"+e.getMessage());
}
finally {
if (out != null) {
System.out.println("Closing PrintWriter");
out.close();
} else {
System.out.println("PrintWriter not open");
}
}
}
public static void main(String [] args){
ListOfNumbers num=new ListOfNumbers();
num.writeList();
}
}
问题:这四个异常代表的意思以及如何改动程序会使得IOException NullPointerException NegativeArraySizeException 异常出现?