CODEWITHSUNDEEP
javacollectionsarraylisttostring
JohnnnnnY
JohnnnnnY

Reputation: 35

ArrayList and toString

I'd like to ask that, how can i use ArrayList to store a toString(). I've got a class, with a toString at the end, and i have to store the toString from the class into the ArrayList.

Like this : Music name , author , release year , currently playing String , String , int , boolean

Upvotes: 0

Views: 613

Answers (5)

dghtr
dghtr

Reputation: 581

List<String> listDesired = new ArrayList<String>( 10 );

Upvotes: 0

Marko Topolnik
Marko Topolnik

Reputation: 200148

You can use the "" + x trick so as to avoid NullPointerException in case an x is null:

public List<String> musicToString(List<Music> musicList) {
  final List<String> strings = new ArrayList<String>();
  for (Music m : musicList) strings.add("" + m);
  return strings;
}

This works because the concatenation operator + implicitly calls String.valueOf on all reference-typed operands.

You can also write String.valueOf explicitly, if that is your aesthetic preference. It also has the marginal benefit of definitely not instantiating a StringBuilder (although there's a good chance the compiler will avoid that anyway since it can see the empty string literal).

Upvotes: 1

Ashwinee K Jha
Ashwinee K Jha

Reputation: 9307

Question is unclear, but if your objects already have toString() method defined you don't need to store them separately in array list. Just add the objects to arrayList and do Collections.toString(yourList);

Upvotes: 1

Bhavik Ambani
Bhavik Ambani

Reputation: 6657

You should override the toString() for that class and in toString() method define the business logic that will convert that string into ArrayList object.

Upvotes: 0

Ravinder Reddy
Ravinder Reddy

Reputation: 23992

hoping you have properly formatted text in your specific class's toString() method,
use 

List<String> listDesired = new ArrayList<String>( 10 );
listDesired.add( myMusicDataClassInstance.toString() );

Upvotes: 2

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