Implementing Comparable - Intro to Java ProgrammingYouTube↗  IA↗(long shot)
Education  5.5K views 15 likes 14 dislikes   23 Feb 2015
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Because strings are comparable, we can sort them by writing one line of code.
文字列は比較できるため 1行のコードを追加するだけでソートできます
If I create an array list of strings and add a whole bunch of things not in any
たくさんの単語を無規則に並べたArrayListを作り
order, and then I want to print them out in alphabetical order, I can add the
アルファベット順に表示させたいとします
line collections.sort strings. Collections is a class a little bit like a race that has some useful utility methods. If I compile and run this code, it will print out all of the animals that I added to the list, but from A to W. We
Collections．sort（strings）と 追記すればいいのです Collectionsクラスには便利で 実用的なメソッドが多数含まれています このコードをコンパイルして実行すると リスト上の動物がAからWの順に表示されます
might want to be able to sort countries like this too. Let's say countries are naturally ordered by their areas. Let's implement the compareTo method for countries. I want to be able to make an array of countries like this, and then
国についても同じようにしたいと思います 国は面積の順番に並べてみましょう 国に対してcompareToメソッドを実装します このように国の配列を表示したいと思います
use the sort method in the arrays class to sort all of the countries in the array, so that this will work. Let's implement the comparable method for
Arraysクラスにあるsortメソッドを使って 配列に存在するすべての国をソートします
countries. We'll need to make the country measurable and also comparable. Now
Countryクラスに comparebleメソッドを実装しましょう CountryクラスにMeasurableと Comparableを実装します
the method should be public and return an int. It's called compareTo, and it
メソッドはpublicでint型を返します そしてcompareToメソッドを呼び出し
takes an object, otherObject. Now if we want to compare otherObject to this
otherObjectでオブジェクトを取り込みます otherObjectをオブジェクトと比較する場合は
object, the first thing we'll need to do is check whether otherObject actually has a name and an area. If otherObject is not a country, then it doesn't really make sense to compare it to this country. If you keep studying Java, you'll figure out how to avoid this cast using generics. For now though, let's focus
まず最初に名前と面積が存在するかチェックします otherObjectが国でない場合 国を比較させる意味がありません Javaを学んでいくとキャストせずに 対応する方法が分かるようになりますが
on the compareTo method. For now, fill in the code, so that compareTo works as I described before for countries. Return a negative number if this country is smaller than other, positive is this country is larger, zero if the two
今はcompareToメソッドについて集中しましょう compareToメソッドを使って 先ほどの国についてのコードを記述してください 国の面積が他と比較して小さい場合は負の値を返し
countries are equal. And notice, I implemented .equals for you. So, you can use
大きい場合は正の値を返し 両方が一致すればゼロを返します 私が．equalsを実装したので このまま使ってください
this. And if the countries are exactly the same size, you can break ties using the name. Can you fill in the rest for me?
国の面積が完全に一致する場合は 国名を比較してください 残りを埋めてみましょう
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