String

[Sujatha Rangarajan]

Hi,
for following code:
class sample
{
public static void main(String[] args)
{
String a="abc";
String b=new String("abc");


System.out.println("Hello World!"+a==b);
}
}
output: false
can anyone explain the reason why "Hello World!" is not printed?

Thanks

[Gaurav Singh]

I think its because your concatenation operator (+) has higher precedence than == operator

[Sujatha Rangarajan]

but how that stop hello world getting printed..i didnt get the point..please can you explain it..

[Gaurav Singh]

Well what you are doing is that first you concatenate the two strings "hello world" and "abc" and then compare it with another string, and finally print out the boolean result.
Hope thats clear.

I guess this question should have been posted in beginners forum.

[Ulf Dittmer]

String equality is tested by the "equals" method. It's rarely correct to compare strings using "==". More information can be found here.

[Ela Jha]

Here a is created in the String Pool while b is an object created in heap.
== operator compares the object reference so obviously it wud result into false

[Matt Harrah]

The problem -- "why wasn't Hello World printed" -- is exactly what Guarav Singh pointed out - operator prcedence.

The + operator has higher precedence than the == operator. Because of this, the line:
System.out.println("Hello World!"+a==b);
is treated identically to
System.out.println(("Hello World!"+a)==b);

So, what gets printed is a comparison of two references. One reference is to the string "Hello World!abc" and the other reference is to the string "abc". The two references are unequal, so false gets printed. The contents of the strings never get compared or even considered in this example.
[ August 23, 2006: Message edited by: Matt Harrah ]

[Shaan Shar]

Originally posted by Matt Harrah:
The problem -- "why wasn't Hello World printed" -- is exactly what Guarav Singh pointed out - operator prcedence.

The + operator has higher precedence than the == operator. Because of this, the line:
System.out.println("Hello World!"+a==b);
is treated identically to
System.out.println(("Hello World!"+a)==b);

So, what gets printed is a comparison of two references. One reference is to the string "Hello World!abc" and the other reference is to the string "abc". The two references are unequal, so false gets printed. The contents of the strings never get compared or even considered in this example.

[ August 23, 2006: Message edited by: Matt Harrah ]

OOps I also missed that..???


BTW UD you took at wrong direction