Checking if values are the same

[francan00]

I currently have two String objects I check to find out if they are
the same value:

String str1 = "red";
String str2 = "yellow";
if (str1.equals(str2)){
System.out.println("Equal");
}
else{
System.out.println("Not equal");
}


Now I need to check 10 objects. How would I check 10 objects to find
out if any of them have the same value?

Please advise.

 

[Are Nybakk]

I currently have two String objects I check to find out if they are
the same value:

String str1 = "red";
String str2 = "yellow";
if (str1.equals(str2)){
System.out.println("Equal");
}
else{
System.out.println("Not equal");
}


Now I need to check 10 objects. How would I check 10 objects to find
out if any of them have the same value?

Please advise.

Couldn't you just iterate through a String array? Or add the Strings to
two collections and check equality that way?

 

[Lew]

I currently have two String objects I check to find out if they are
the same value:

String str1 = "red";
String str2 = "yellow";
if (str1.equals(str2)){
System.out.println("Equal");
}
else{
System.out.println("Not equal");
}

Now I need to check 10 objects. How would I check 10 objects to find
out if any of them have the same value?

Variations on:

Collection <Thing> mightHaveDupes = getSomeCollection();
Collection <Thing> noDupes = new WhateverCollection <Thing> ();
// we'll get back to which Collection implementation to use

for ( Thing thing : mightHaveDupes )
{
if ( noDupes.contains( thing ))
{
log( "Thing {"+ thing +"} is duplicated." );
}
else
{
noDupes.add( thing );
}
}

If the copy is a Set, then duplication is avoided automatically:

public <T> boolean hasDupes( Collection<T> mayHave )
{
Set<T> copy = new HashSet<T> ( mayHave );
return (copy.size() < mayHave.size());
}

 

[Daniel Pitts]

I currently have two String objects I check to find out if they are
the same value:

String str1 = "red";
String str2 = "yellow";
if (str1.equals(str2)){
System.out.println("Equal");
}
else{
System.out.println("Not equal");
}


Now I need to check 10 objects. How would I check 10 objects to find
out if any of them have the same value?

Please advise.

The easiest way would probably be to add them to a Set of some sort
(HashSet probably). Set.add() will return false if that value was
already in the set.

 

[francan00]

Variations on:

Collection <Thing> mightHaveDupes = getSomeCollection();
Collection <Thing> noDupes = new WhateverCollection <Thing> ();
// we'll get back to which Collection implementation to use

for ( Thing thing : mightHaveDupes )
{
if ( noDupes.contains( thing ))
{
log( "Thing {"+ thing +"} is duplicated." );
}
else
{
noDupes.add( thing );
}

}

If the copy is a Set, then duplication is avoided automatically:

public <T> boolean hasDupes( Collection<T> mayHave )
{
Set<T> copy = new HashSet<T> ( mayHave );
return (copy.size() < mayHave.size());

}

Thanks, I dont have Generics in my Java 1.4 environment.

How would this be without Generics?

public <T> boolean hasDupes( Collection<T> mayHave )
{
Set<T> copy = new HashSet<T> ( mayHave );
return (copy.size() < mayHave.size());

}

 

[Patricia Shanahan]

How would this be without Generics?

public <T> boolean hasDupes( Collection<T> mayHave )
{
Set<T> copy = new HashSet<T> ( mayHave );
return (copy.size() < mayHave.size());

}

Just delete all instances of "<T>".

Patricia

 

[Are Nybakk]

Couldn't you just iterate through a String array? Or add the Strings to
two collections and check equality that way?

I think I misunderstood somewhat - should be one collection and you can
check if it contains your string.

Lew's solution, however, is quite elegant.

 

[Roedy Green]

Now I need to check 10 objects. How would I check 10 objects to find
out if any of them have the same value?

You want an array of Strings. You compare each of them against the
first one. See http://mindprod.com/jgloss/array.html