arraylist undefined method for type

Question

I have a method which takes an ArrayList<Song> as argument. the class song has different methods like getTitle(), getInterpret(), toString(), toString2()...

public class Song implements Comparable<Song>{

    private String title;
    private String interpret;
    
    public Song(String title,String interpret){
        
        this.title=title;
        this.interpret=interpret;
        
    }

    public String getTitle() {
        return title;
    }

    public String getInterpret() {
        return interpret;
    }

    
    public String toString2(){
        return title+" - "+interpret;
    }

    @Override
    public int compareTo(Song otherSong) {
        
        return title.compareToIgnoreCase(otherSong.getTitle());
    }

    public String toString() {
        
        return interpret+" - "+title;
    }

}

the method printList takes an ArrayList of Song as argument:

public <Song> void printList(ArrayList<Song> songList,String sortBy){
    
    JLabel track;
            
    for(int i=0;i<songList.size();i++){

        if(sortBy=="Artist"){
        track = new JLabel("\n- "+songList.get(i).toString());}

        else if(sortBy=="Song"){
        track = new JLabel("\n- "+songList.get(i).toString2());}
        
    }

I have an error on songList.get(i).toString2(), the method toString2() is undefined for type Song, it seems like I can only access to the method of the class Object.

Can somebody help please?

why do you name method toString2() ?

Ravi
– Ravi

2017-04-02 10:48:42 +00:00
Commented Apr 2, 2017 at 10:48 — Ravi
– Ravi, Commented Apr 2, 2017 at 10:48
hi, because toString2() is just a variation of toString()

Greg Artisi
– Greg Artisi

2017-04-02 11:08:40 +00:00
Commented Apr 2, 2017 at 11:08 — Greg Artisi
– Greg Artisi, Commented Apr 2, 2017 at 11:08

JB Nizet · Accepted Answer · 2017-04-02 10:50:05Z

3

You've made your method generic, and chose to name the generic type Song. It shouldn't be generic:

public void printList(ArrayList<Song> songList,String sortBy){

Also, compare strings with equals(), not ==.

answered Apr 2, 2017 at 10:50

JB Nizet

694k94 gold badges1.3k silver badges1.3k bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Greg Artisi Over a year ago

thank you for your answer, but when i remove the "<Song>" in the method declaration, the compiler tells me "Song cannot be resolved to a type", do you know why?

Collectives™ on Stack Overflow

arraylist undefined method for type

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related