please explain me the output of the following programs

[kanna kesavan]

please explain me the output of the following programs

1.
public class AQuestion
{
private int i = giveMeJ();
private int j = 10;

private int giveMeJ()
{
return j;
}

public static void main(String args[])
{
System.out.println((new AQuestion()).i);
}
}

ans:0(zero)

2.if(" String ".trim() == "String")
System.out.println("Equal");
else
System.out.println("Not Equal");
ans rints "not Equal:.

[Srinivasa Raghavan]

1. Member variables gets initialized only after the call to constructor is finished hence 0.
Try this it works.

public class AQuestion 
{ 
private int i = giveMeJ(); 
private int j = 10; 
 
private int giveMeJ() 
{ 
return j; 
} 
 
public static void main(String args[]) 
{ 
//System.out.println((new AQuestion()).i); 
AQuestion x = new AQuestion();
System.out.println( ( x.i = x.giveMeJ() ) );
} 
} 
  

2. Use .equals instead.
String.trim produces a new Object

[Stefan Willi]

The answer of your second question:
If you use the == Operator, then you compare the references of an Object, not there value.

after " String ".trim() you got a new reference to a String Object, which contains the value "String".

To compare the value of 2 Strings, you have to use equals() or equalsIgnoreCase().

Stefna

[Stefan Willi]

Let me take one addition.

Don't be confused by the result of the following code

public void confuseMe(){
  String first = "first";
  String second = "first";
 
  if(first == second){
    System.out.println("This would be true!!");
  }

If you try to compare Strings in this manner, you have to know, that there are not two strings createt. Java uses a Literal-Pool and uses for the property first and second the same String-Object. So the references are the same and the == Operator would return TRUE.

Stefan

[fred rosenberger]

the trim() method will return a reference to a new object. In this case, it will refer to a newly created string with a value of "String".

in other words, you will end up with 3 String objects created. two in the string pool (with values of " String " and "String"), and a third created by the trim() call. since the == operator checks to see if we refer to the same object, we get a false.

if you had instead done

if((" String ".trim()).equals("String"))
   System.out.println("Equal");
else
   System.out.println("Not Equal");

after being chastized for writing such an ugly test condition, you'd get a true (assuming i didn't make any typos).