Cannot get if statment to work correctly

[croucherj3]

Hi, I am a COBOL programmer trying to learn Java. I just wrote a quick program, but when I execute it, it doesn't give the expected results. The code:

class PasswordB
{
public static void main(String[] args) throws Exception
{
char p1, p2, p3, p4;
System.out.print("Enter a four letter password: "

p1 = (char)System.in.read();
p2 = (char)System.in.read();
p3 = (char)System.in.read();
p4 = (char)System.in.read();

System.out.println("You entered: " + p1 + p2 + p3 + p4);

if(p1 == 'B')
System.out.println(p1 + p2 + p3 + p4 + " is a valid password"
else
System.out.println(p1 + p2 + p3 + p4 + " isnt a valid password"
}
}


Sample execution:
Enter a four letter password: Bffd
You entered: Bffd
370 is a valid password


When I execute it, the println statments following the if statment print numbers instead of letters.
It seems as though the (p1 == 'B') is trying to assign B rather than test it.

Any comments would be appericiated

Thanks,
John
Athens, OH

 

[maxpower1]

Be careful when you use the + sign in your System.out.println. For instance, if you do this:-

int x = 2;
int y = 3;

System.out.println(x + y); //will print out 5

but

System.out.println(&quot;Result is <&quot; + x + y); //will print out
//Result is 23

but

System.out.println(&quot;Result is <&quot; + (x + y)); //will print
//out Result is 5



I would suggest use the parentheses as well. Copy the below code and name it TestPassword.java
and see what I mean.

public class TestPassword
{
public static void main(String[] args) throws Exception{
char p1, p2, p3, p4;
System.out.print(&quot;Enter a four letter password: &quot;

p1 = (char)System.in.read();
p2 = (char)System.in.read();
p3 = (char)System.in.read();
p4 = (char)System.in.read();

System.out.println(&quot;You entered: &quot; + p1 + p2 + p3 + p4);

if(p1 == 'B'){
//talk like Yoda to get the right result.
System.out.println(&quot;a valid password&quot; + p1 + p2 + p3 + p4 + &quot; it is&quot; );
}
else {
System.out.println(p1 + p2 + p3 + p4 + &quot;isnt a valid password&quot;
}
}
}


~za~
You can't bring back a dead thread!

 

[hologram]

I have answered the same question in a previous post, but I can't find it anymore. The output of &quot;System.out.println()&quot; does not seem consistent. I don't know whether you could consider this a bug in java. Sun knows about it for a long time (years), but they don't consider it a bug.

System.out.println("" + p1 + p2 + p3 + p4  + " is a valid password" );

will also do the trick. See also Thread269-603639.
The output of
[code
System.out.println(p1 + p2 + p3 + p4 + &quot; is a valid password. A valid password &quot; + p1 + p2 + p3 + p4 + &quot; it is&quot; );
[/code]
is :
===============================
Enter a four letter password: Bffd
You entered: Bffd
370 is a valid password. A valid password Bffd it is
===============================
java works from left to right, so the result of 'p1 + p2' is a number, after + p3 and + p4 the result stays a number. It is only after addding &quot; is a ..&quot; that a converion to String takes place. You can play around and see what the result is of :

System.out.println(p1);  // B
System.out.println(p2);  // f
System.out.println(p3);  // f
System.out.println(p4);  // d
System.out.println(p1 +  p2);  //168
System.out.println(p1 + "" +  p2);  // Bf

 

[croucherj3]

Hey thanks for the help maxpower1 and hologram. Tried both of you suggestions and they worked. I would consider this to be a bug but maybe Sun calls it a feature?

Once again, thanks for the help.

John
Athens, OH