Boolean declaration and initialization

[Kaz Yosh]

This is from javacertificate.com
The answer is 1
At line 3, Boolean is declared and initialized.
Is this "correct" correct?

1. public class Wrapper {
2. public static void main(String[] args) {
3. Boolean b = new Boolean("correct");
4. try {
5. Byte by = new Byte("201");
6. Integer i = new Integer("123");
7. Double db = new Double(2.2d);
8. } catch (NumberFormatException nfe) {
9. System.out.println ("Bad number!");
10. }
11. }
12. }

1 NumberFormatException when executing line 5
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2 NumberFormatException when executing line 7
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3 No output is generated
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4 Exception is thrown at line 3, incorrect boolean value
�
5 Compile time error

[Meg Adal]

For Boolean with constructor

 public Boolean(String s)  
 

It creates Boolean object with value "true" if the String s is "true" (in lower/upper case)
So for

Boolean b = new Boolean("true"); // b.toString() is true
Boolean b = new Boolean("True"); // b.toString() is true
Boolean b = new Boolean("TRUE"); // b.toString() is true
 

For all other string values it creates Boolean object with false value.
Boolean b = new Boolean("false"); // b.toString() is false
Boolean b = new Boolean("correct"); // b.toString() is false
Boolean b = new Boolean("right"); // b.toString() is false
I hope this will help you.
[ May 27, 2003: Message edited by: Megan Adal ]

[Ryan Wilson]

Originally posted by Kaz Yosh:
At line 3, Boolean is declared and initialized.
Is this "correct" correct?
Boolean b = new Boolean("correct");

This is correct. Boolean has a custructor that accepts a String. If the String is equal to "true" (ignores case) then the Boolean is set to true. Any other String will result in "false"
The following is from Sun

public Boolean(String s)Allocates a Boolean object representing the value true if the string argument is not null and is equal, ignoring case, to the string "true". Otherwise, allocate a Boolean object representing the value false. Examples:
new Boolean("True") produces a Boolean object that represents true.
new Boolean("yes") produces a Boolean object that represents false.

Parameters:
s - the string to be converted to a Boolean.

[Kaz Yosh]

Now I can say with confident that
NumberFormatException occurs on line 5.
thank you