Thread: Removing an object from an ArrayList

How can I remove an object from an ArrayList? If you run my code, my delete method in the Team class does not seem to be able to remove the object that I typed from the keyboard.

the remove() method seems so have no effect even though that is how you remove an object from arraylist object that I removed is still there

delete method I created to remove object from ArrayList:

HTML Code:

	public void delete() throws IOException {
		System.out.println("Enter the name of the file that you wish to delete information from: ");
		String name = scan.next();
		File w = new File(name);
		if(w.exists())
		{
		    ArrayList<Player> x = new ArrayList<Player>();
		    try {
		       Stream<String> lines = Files.lines(Paths.get(name));
		       lines.forEach((String t) -> {
		          String[] parse = t.split(" ");
		          if(parse.length<5) return;
		          x.add(new Player(parse[0], parse[1], parse[2], parse[3], parse[4]));
		       });
		    } catch (IOException ex) {
		       System.out.println("Unable to open student file." + ex.toString());
		    }
			System.out.println("Size of Player ArrayList: " + x.size());
			System.out.println();

			for(int i=0;i<x.size();i++){  //Prints objects from chosen file to console
		    	System.out.println(x.get(i));
		    }

		    System.out.println("How many people would you like to remove? ");
			int num_people = scan.nextInt();
			System.out.println("Enter first, last, goals, caps, and assists:");
			for(int i=0; i<num_people; i++){
				String fstname2 = scan.next();
				String lstname2 = scan.next();
				String goals = scan.next();
				String caps = scan.next();
				String assists = scan.next();
				x.remove(new Player(fstname2,lstname2,goals,caps,assists));
			}
			System.out.println("Done.");
			System.out.println();
			for(int i=0;i<x.size();i++){ 
		    	System.out.println(x.get(i));
		    }
			BufferedWriter q = new BufferedWriter(new FileWriter(w));
		    for(Player p : x){
		    	q.write(p + "\n");
		    	q.newLine();
		    }
		    q.close();
		}
		else{
			System.out.println("File does not exist.");
        }
	}

I'm already using the correct method to delete the certain object though. I don't need a boolean because I already know that it doesn't work

Because there is no other way that I know of to delete an object. Is there an alternative to remove()?

And how can I reference an object that is already in the ArrayList?

How does the get method return a reference to an object in the list?

I created an equals method in the Player class but have not used it.

--- Update ---

This is my method when I added the equals function and used a getter to get all of the objects in the existing arraylist. I made a loop to test if the object I entered in from the keyboard is equal to any of the ones in the arraylist, but it still doesn't work.

HTML Code:

	public void delete() throws IOException {
		System.out.println("Enter the name of the file that you wish to delete information from: ");
		String name = scan.next();
		File w = new File(name);
		if(w.exists())
		{
		    ArrayList<Player> x = new ArrayList<Player>();
		    try {
		       Stream<String> lines = Files.lines(Paths.get(name));
		       lines.forEach((String t) -> {
		          String[] parse = t.split(" ");
		          if(parse.length<5) return;
		          x.add(new Player(parse[0], parse[1], parse[2], parse[3], parse[4]));
		       });
		    } catch (IOException ex) {
		       System.out.println("Unable to open student file." + ex.toString());
		    }
			System.out.println("Size of Player ArrayList: " + x.size());
			System.out.println();

			for(int i=0;i<x.size();i++){
		    	System.out.println(x.get(i));
		    }

		    System.out.println("How many people would you like to remove? ");
			int num_people = scan.nextInt();
			System.out.println("Enter first, last, goals, caps, and assists:");
			for(int i=0; i<num_people; i++){
				String fstname2 = scan.next();
				String lstname2 = scan.next();
				String goals = scan.next();
				String caps = scan.next();
				String assists = scan.next();
				Player y = new Player(fstname2,lstname2,goals,caps,assists);
				for(int j=0;j<x.size();j++){
					if(y.equals(x.get(j))){
						x.remove(j);
					}
			    }
			}
			
			System.out.println("Done.");
			System.out.println();
			for(int i=0;i<x.size();i++){
		    	System.out.println(x.get(i));
		    }
			BufferedWriter q = new BufferedWriter(new FileWriter(w));
		    for(Player p : x){
		    	q.write(p + "\n");
		    	q.newLine();
		    }
		    q.close();
		}
		else{
			System.out.println("File does not exist.");
        }
	}

I think I got it now, thanks!

I created my equals method like this:

HTML Code:

	public boolean equals(Player other){
		return(true);
	}

Now it works perfectly fine.

I replaced

HTML Code:

public boolean equals(Player other){
	return(true);
}

with

HTML Code:

public boolean equals(Object other) {
    if (this == other)
        return true;
    if (other == null || getClass() != other.getClass())
        return false;
    Player player = (Player) other;
    return (fstname.equals(player.fstname) && lstname.equals(player.lstname));
    }

and now it works.