Consider my new CodeRanchUser class

[Mike Savvy]

My new project, I did my best. Critique welcome  

package justOneHundredLinesOfCode;
import java.util.ArrayList;
import java.util.List;
import java.util.function.Predicate;
public class MyExample {
	public static void main(String[] args) {
		List<CodeRanchUser> users = new ArrayList<CodeRanchUser>();
		CodeRanchUser jeanneBoyarsky = new CodeRanchUser("Jeanne Boyarsky", 2003, "author & internet detective");
		users.add(jeanneBoyarsky);
		jeanneBoyarsky.setAuthor(true);
		users.add(new CodeRanchUser("Campbell Ritchie", 2005, "Marshal"));
		users.add(new CodeRanchUser("Paul Clapham", 2005, "Marshal"));
		users.add(new CodeRanchUser("Mike Savvy", 2019, "Ranch Hand" ));
		print(users, u -> u.isMarshal());
		print(users, u -> u.isAuthor());
		System.out.println(users.get(3).toString());
		System.out.println("Jeanne is an author: "+ users.get(0).isAuthor());
		System.out.println("Campbell is a Marshal: " + users.get(1).isMarshal());
		System.out.println("my userID: " + users.get(3).getUserID());
		System.out.println("Paul is joined: " + users.get(2).yearJoined);
	}
	/**
	 * check for any trait
	 * @param users - data base of users
	 * @param checker - Predicate
	 */
	private static void print(List<CodeRanchUser> users, Predicate<CodeRanchUser>checker) {
		for (CodeRanchUser user : users) {
			if (checker.test(user))
				System.out.println(user + " ");
		}
		System.out.println();
	}
}

/**
 * @author Mihail Savvateev
 */
class CodeRanchUser {
	private static int ID_COUNTER = 0;
	public final int userID;
	private String name;
	public final int yearJoined;
	private String post;
	private boolean author;
	
	/**
	 * @param name
	 * @param yearJoined
	 * @param post
	 */
	public CodeRanchUser(String name, int yearJoined, String post) {
		this.name = name;
		this.yearJoined = yearJoined;
		this.post = post;
		userID = ++ID_COUNTER;
	}
	/**
	 * @return ID of this user
	 */
	public int getUserID() {
		return userID;
	}
	/**
	 * @return true value if this person is a Marshal
	 */
	public boolean isMarshal() {
		return post=="Marshal";
	}
	/**
	 * @return true if this person is an Author
	 */
	public boolean isAuthor() {
		return author;
	}
	/**
	 *	String representation of this person (name, post, year)
	 */
	public String toString() {
		return name + ", " + post + ", joined " + yearJoined;
	}
	/**
	 * @param name - new name for this person
	 */
	public void setName(String name) {
		this.name = name;
	}
	/**
	 * @param post - new post for this person
	 */
	public void setPost(String post) {
		this.post = post;
	}
	/**
	 * @param author - set this person author or not author
	 */
	public void setAuthor(boolean author) {
		this.author = author;
	}
}

[Carey Brown]

class CodeRanchUser {    private static int ID_COUNTER = 0;    public final int userID;    private String name;    public final int yearJoined;    private String post;    private boolean author;        /**     * @param name     * @param yearJoined     * @param post     */    public CodeRanchUser(String name, int yearJoined, String post) {        this.name = name;        this.yearJoined = yearJoined;        this.post = post;        userID = ++ID_COUNTER;    }    /**     * @return ID of this user     */    public int getUserID() {        return userID;    }    /**     * @return true value if this person is a Marshal     */    public boolean isMarshal() {        return post=="Marshal";    }    /**     * @return true if this person is an Author     */    public boolean isAuthor() {        return author;    }    /**     *  String representation of this person (name, post, year)     */    public String toString() {        return name + ", " + post + ", joined " + yearJoined;    }    /**     * @param name - new name for this person     */    public void setName(String name) {        this.name = name;    }    /**     * @param post - new post for this person     */    public void setPost(String post) {        this.post = post;    }    /**     * @param author - set this person author or not author     */    public void setAuthor(boolean author) {        this.author = author;    } }

All upper case names are usually reserved for constants, as in static final. Your ID_COUNTER technically doesn't qualify though it does make it stand out in the code.

I would prefer that 'author' had been named 'isAuthor'. I know that's what the getter is but using 'is' also helps with variable names.

Line 68, use equals() and not '=='.

Need a getter for yearJoined.

[Carey Brown]

yearJoined should be private.

userID should be private.

[Carey Brown]

    public boolean isMarshal() {
        return post=="Marshal";
    }

The rank of an individual should be handled as an enum.

[Paul Clapham]

Carey Brown wrote:

    public boolean isMarshal() {
        return post=="Marshal";
    }

The rank of an individual should be handled as an enum.

Not necessarily; notice that Mike has "author & internet detective" as one of the possibilities.

[Carey Brown]

public class MyExample {    public static void main(String[] args) {        List<CodeRanchUser> users = new ArrayList<CodeRanchUser>();        CodeRanchUser jeanneBoyarsky = new CodeRanchUser("Jeanne Boyarsky", 2003, "author & internet detective");        users.add(jeanneBoyarsky);        jeanneBoyarsky.setAuthor(true);        users.add(new CodeRanchUser("Campbell Ritchie", 2005, "Marshal"));        users.add(new CodeRanchUser("Paul Clapham", 2005, "Marshal"));        users.add(new CodeRanchUser("Mike Savvy", 2019, "Ranch Hand" ));        print(users, u -> u.isMarshal());        print(users, u -> u.isAuthor());        System.out.println(users.get(3).toString());        System.out.println("Jeanne is an author: "+ users.get(0).isAuthor());        System.out.println("Campbell is a Marshal: " + users.get(1).isMarshal());        System.out.println("my userID: " + users.get(3).getUserID());        System.out.println("Paul is joined: " + users.get(2).yearJoined);    }    /**     * check for any trait     * @param users - data base of users     * @param checker - Predicate     */    private static void print(List<CodeRanchUser> users, Predicate<CodeRanchUser>checker) {        for (CodeRanchUser user : users) {            if (checker.test(user))                System.out.println(user + " ");        }        System.out.println();    } }

        List<CodeRanchUser> users = new ArrayList<CodeRanchUser>();

should be

        List<CodeRanchUser> users = new ArrayList<>();

Management of a collection of CodeRanchUser objects should be encapsulated in its own class, e.g. CodeRanchUsers (plural).

Line 16, don't need toString() call.

Line 30, why the trailing space?

Users should be added through CodeRanchUsers which should return an ID. From there on all access should be via the ID and not an ordinal position in the List because CodeRanchUsers may or may not choose to implement a List. So the use of get(3), for example, would be replaced by a retrieval by ID.

[Carey Brown]

Paul Clapham wrote:

Carey Brown wrote:

    public boolean isMarshal() {
        return post=="Marshal";
    }

The rank of an individual should be handled as an enum.

Not necessarily; notice that Mike has "author & internet detective" as one of the possibilities.

I submit that the rank is an exclusive value and an enum is appropriate. isAuthor and isDetective may be additional boolean qualifiers.

[Mike Savvy]

I have changed so far, but do not really understand what/how exactly CodeRanchUsers class should be? Carey Brown

package superLambdas;
import java.util.ArrayList;
import java.util.List;
import java.util.function.Predicate;
public class MyExample {
	public static void main(String[] args) {
		List<CodeRanchUser> users = new ArrayList<>();
		CodeRanchUser jeanneBoyarsky = new CodeRanchUser("Jeanne Boyarsky", 2003, "author & internet detective");
		users.add(jeanneBoyarsky);
		jeanneBoyarsky.setAuthor(true);
		users.add(new CodeRanchUser("Campbell Ritchie", 2005, "Marshal"));
		users.add(new CodeRanchUser("Paul Clapham", 2005, "Marshal"));
		users.add(new CodeRanchUser("Mike Savvy", 2019, "Ranch Hand" ));
		print(users, u -> u.isMarshal());
		print(users, u -> u.isAuthor());
		System.out.println(users.get(3));
		System.out.println("Jeanne is an author: "+ users.get(0).isAuthor());
		System.out.println("Campbell is a Marshal: " + users.get(1).isMarshal());
		System.out.println("my userID: " + users.get(3).getUserID());
		System.out.println("Paul is joined: " + users.get(2).getYearJoined());
	}
	/**
	 * check for any trait
	 * @param users - data base of users
	 * @param checker - Predicate
	 */
	private static void print(List<CodeRanchUser> users, Predicate<CodeRanchUser>checker) {
		for (CodeRanchUser user : users) {
			if (checker.test(user))
				System.out.println(user);
		}
	}
}
/**
 * @author Mihail Savvateev
 *
 */
class CodeRanchUser {
	private static int counterID = 0;
	private final int userID;
	private String name;
	private final int yearJoined;
	private String post;
	private boolean isAuthor;
	
	/**
	 * @param name
	 * @param yearJoined
	 * @param post
	 */
	public CodeRanchUser(String name, int yearJoined, String post) {
		this.name = name;
		this.yearJoined = yearJoined;
		this.post = post;
		userID = ++counterID;
	}
	/**
	 * @return year when this person has joined CodeRanch
	 */
	public int getYearJoined() {
		return yearJoined;
	}
	/**
	 * @return ID of this user
	 */
	public int getUserID() {
		return userID;
	}
	/**
	 * @return true value if this person is a Marshal
	 */
	public boolean isMarshal() {
		return post.equals("Marshal");
	}
	/**
	 * @return true if this person is an Author
	 */
	public boolean isAuthor() {
		return isAuthor;
	}
	/**
	 *	String representation of this person (name, post, year)
	 */
	public String toString() {
		return name + ", " + post + ", joined " + yearJoined;
	}
	/**
	 * @param name - new name for this person
	 */
	public void setName(String name) {
		this.name = name;
	}
	/**
	 * @param post - new post for this person
	 */
	public void setPost(String post) {
		this.post = post;
	}
	/**
	 * @param author - set this person author or not author
	 */
	public void setAuthor(boolean isAuthor) {
		this.isAuthor = isAuthor;
	}
}

[S Fox]

to shorten up the code these things should just be 1 line.

    /**
     * @param author - set this person author or not author
     */

also, can you explain to me what this line is, do we have pointers in java now?
( i know its probably a lambda of some sort )

print(users, u -> u.isMarshal());

[Campbell Ritchie]

Urma Fusco and Mycroft Modern Java in Action (Manning) or Java8 in Action (=same book, older edition).
Java™ Tutorials section.

[Mike Savvy]

Campbell Ritchie wrote:Urma Fusco and Mycroft Modern Java in Action (Manning) or Java8 in Action (=same book, older edition).
Java™ Tutorials section.

What do you mean? For CodeRunchUsers?

[Campbell Ritchie]

It was a reply to S Fox's post. Useful resources.

[Piet Souris]

S Fox wrote:also, can you explain to me what this line is, do we have pointers in java now?
( i know its probably a lambda of some sort )

print(users, u -> u.isMarshal());

Yes it is. If you look at Mike's definition of the print method, you see that the second parameter is a Predicate. u -> u.isMarshall() is indeed a Predicate.

Petite question for Mike:
if you want to print ALL members, what Predicate would you use? Or you could overload the print-method, leaving out that Predicate as parameter. What would you prefer?

[Knute Snortum]

If you want to practice streams, you could turn the print method into a stream.

[Mike Savvy]

Okay, I was confused because there is not about lambdas, but about nested classes    Campbell

[Mike Savvy]

Piet Souris and Knute Snortum I am not sure I must know about, since it is not in scope of OCAJ SE8 exam, which I will take this week. But I can back to this suggestions after exam

[Campbell Ritchie]

That section includes λs. Look on the left of that link. I thought SF would do better to look at the whole section.

[Piet Souris]

Okay, Mike.

Success with your exam!

[Carey Brown]

This is along the lines of what I was thinking of for CodeRanchUsers, keeping future persistence in mind. Others may have some feed back on this.

import java.util.LinkedHashMap;
import java.util.Map;
import java.util.function.Predicate;

public class CodeRanchDemo
{
	static CodeRanchUsers	users = new CodeRanchUsers();
	
	public static void main( String[] args )
	{
		CodeRanchUser jeanneBoyarsky = new CodeRanchUser( "Jeanne Boyarsky",
				2003, "author & internet detective" );
		int jeanneID  = users.add( jeanneBoyarsky );
		jeanneBoyarsky.setAuthor( true );
		
		int campbellID = users.add( new CodeRanchUser( "Campbell Ritchie", 2005, "Marshal" ) );
		int paulID     = users.add( new CodeRanchUser( "Paul Clapham", 2005, "Marshal" ) );
		int mikeID     = users.add( new CodeRanchUser( "Mike Savvy", 2019, "Ranch Hand" ) );
		
		System.out.println(  );
		users.print( u -> u.isMarshal() );
		
		System.out.println(  );
		users.print( u -> u.isAuthor() );
		
		System.out.println(  );
		System.out.println( "Jeanne is an author: " + users.get( jeanneID ).isAuthor() );
		System.out.println(	"Campbell is a Marshal: " + users.get( campbellID ).isMarshal() );
		System.out.println( "my userID: " + users.get( mikeID ).getUserID() );
		System.out.println( "Paul is joined: " + users.get( paulID ).getYearJoined() );
	}
}

/**
 * Manage list of users.
 * TODO save/load persistence
 * TODO update, delete
 */
class CodeRanchUsers
{
	private Map<Integer,CodeRanchUser> users = new LinkedHashMap<>();
	
	/**
	 * @param user
	 * @return user ID or -1 if duplicate user ID
	 */
	public int add( CodeRanchUser user )
	{
		if( users.containsKey( user.getUserID() ) )
			return -1;
		users.put( user.getUserID(), user );
		return user.getUserID();
	}
	
	/**
	 * 
	 * @param id
	 * @return CodeRanchUser or null if not found
	 */
	public CodeRanchUser get( int id )
	{
		return users.get( id );
	}

	/**
	 * print all
	 * @param users - data base of users
	 */
	public void print()
	{
		users.forEach( (k,v) -> System.out.println( v ) );
	}

	/**
	 * check for any trait
	 * @param users - data base of users
	 * @param checker - Predicate
	 */
	public void print( Predicate<CodeRanchUser> checker )
	{
		// TODO probably more elegant way using filter()
		users.forEach( (k,v) -> { if( checker.test(v) ) System.out.println( v ); } );
	}
}

/**
 * @author Mihail Savvateev
 *
 */
class CodeRanchUser
{
        // ...
	
	public int hashCode()
	{
		return userID;
	}
	
	public boolean equals( Object o )
	{
		if( this == o )
			return true;
		if( o == null || o.getClass() != getClass() )
			return false;
		return userID == ((CodeRanchUser)o).userID;
	}
}

[Knute Snortum]

Here's what I was thinking of for the print method:

    private static void print(Predicate<CodeRanchUser>checker) {
    	users.stream()
    		.filter(checker)
    		.forEach(u -> System.out.println(u));
    }