Hash Set in Java

[muj]

I'm working on a project. I am trying to use a HashSet to insert objects in to a set. I then need to pas this set to another class so that I can perform operations on the set. I am using this code


import java.util.HashSet;
import java.util.Set;


public class requirements {


public void HashSet() {

Set requirements = new HashSet();

//Declare some string items
String item_1 = "r1";
String item_2 = "r2";
String item_3 = "r3";

boolean result;

//Add the items to the Set
result = requirements.add(item_1);
System.out.println(item_1 + ": " + result);

result = requirements.add(item_2);
System.out.println(item_2 + ": " + result);

result = requirements.add(item_3);
System.out.println(item_3 + ": " + result);

//Now we try to add item_1 again
result = requirements.add(item_1);
System.out.println(item_1 + ": " + result);

//Adding null
result = requirements.add(null);
System.out.println("null: " + result);

//Adding null again
result = requirements.add(null);
System.out.println("null: " + result);
}


public static void main(String[] args) {
new requirements().HashSet();
}
}


}

But keep getting lots of syntax errors can somebody help me to identify the syntax errors?

Also I want to pass the set to another class, does anybody know what utility in the Java library I need to use?

any help would be very uch appreciated, I am new to Java

Thanks

[Norm]

help me to identify the syntax errors

Can you copy and post the errors here?

to pass the set to another class, does anybody know what utility in the Java library I need to use?

You don't need a library to pass a reference to an object to another class.
Can you explain why calling a method in the other class with a reference to the set as an arg wouldn't solve your problem?

[Lil_Aziz1]

Those are not syntax errors. They are suggestions. In your case, they are type safety. First off, please use the [code] tags when posting code. It retains the indentation. Second, you should read about generics. This is how it should be:

import java.util.HashSet;
import java.util.Set;


public class Requirements {

	public void HashSet() {

		Set<String> requirements = new HashSet<String>();

		//Declare some string items
		String item_1 = "r1";
		String item_2 = "r2";
		String item_3 = "r3";

		boolean result;

		//Add the items to the Set
		result = requirements.add(item_1);
		System.out.println(item_1 + ": " + result);

		result = requirements.add(item_2);
		System.out.println(item_2 + ": " + result);

		result = requirements.add(item_3);
		System.out.println(item_3 + ": " + result);

		//Now we try to add item_1 again
		result = requirements.add(item_1);
		System.out.println(item_1 + ": " + result);

		//Adding null
		result = requirements.add(null);
		System.out.println("null: " + result);

		//Adding null again
		result = requirements.add(null);
		System.out.println("null: " + result);
	}


	public static void main(String[] args) {
		new Requirements().HashSet();
	}
}

The only thing I changed was

Set<String> requirements = new HashSet<String>();

and the class name from 'requirements' to "Requirements."

[muj1]

I am getting these errors

Return type of the method is missing
Syntax error on token class, delete this token
Syntax error on token misplaced construct
Syntax error insert Enum body to complete EnumheaderName
Syntax Error insert Enum body to complete enum decleration
The public type requirements must be defined in its own file.

I have changed the coding to the code provided above.

I thought I would have to use a library to move the Hashset to another class but if there is a better way please do let me know.

[Norm]

I am getting these errors

please copy and paste here the full text of the error messages.

[muj1]

Description
Return type for the method is missing test

resource
requirements.java

Path
project/src/org/test/requirementsproject

resource
requirements.java

Location
line 11


Desription
Syntax error on token "class", delete this token test project/src

Resource
Specification.java

Path
test project/src

Location
line 5


Description
Syntax error on token(s), misplaced construct(s)

Resource
test project/src

Path
Specification.java

Location
line 2

[muj1]

Description
Syntax error, insert "enum Identifier" to complete EnumHeaderName

Resource
test project/src

Path
Specification.java

Location
line 5


Description
Syntax error, insert "EnumBody" to complete EnumDeclaration

Resource
test project/src


Path
Specification.java

Location
line 5


Description
The public type requirements must be defined in its own file

Resource
test project/src

Path
Specification.java

Location
line 5


I have another class called specification which is currently empty. I am using Ecplise.

[Norm]

What is line 5? all the error messages point to it as the problem.
Your posting of compile error messages is different. On my system I get:
Please copy full text of error message and paste it here. Here is a sample:

TestSorts.java:138: cannot find symbol
symbol  : variable var
location: class TestSorts
         var = 2;
         ^

[muj1]

this is line 5

Set<String> requirements = new HashSet<String>();

i get those errors in my ecplise problems bar at the nottom of my screen

[Norm]

Sorry, I don't know about your IDE. I use the javac program to compile my programs.
The error message texts you posted don't include all the same information that the javac program generates.

Is the line of code you show where the error messages occurred?

[muj1]

thats line 5 in my code the line that you said had errors in it.

[Norm]

Location
line 5

I thought that the 'line 5' from your post would be to the error.
I don't know where the lines you posted come from. Your IDE doesn't give good error messages.

Can you compile your program with javac and post the errors it generates. See my post#8 for the format of the javac errors.

[JosAH]

The original program compiles fine with me; there are just a few warnings about using a raw type Set but that's all; I did this in Eclipse; I think the OP is not showing us the code that s/he is trying to compile ...

kind regards,

Jos

[Norm]

We need a crystal ball to be able to help. Or a webcam poised over the shoulder of the OP so we can see what they are doing.

[JosAH]

We need a crystal ball to be able to help. Or a webcam poised over the shoulder of the OP so we can see what they are doing.

Or a remote controlled chainsaw it we have to slightly correct them ...

kind regards,

Jos ;-)