リンクを新しいタブで開く
  1. 123

    The new operator in Java is used to create new objects and allocate memory for them at runtime. It is a fundamental part of object-oriented programming in Java, allowing developers to instantiate classes and initialize objects.

    Creating Objects with new

    When you declare a class in Java, you are defining a new data type. However, to create an actual object from this class, you need to follow a two-step process:

    • Declaration: First, declare a variable of the class type. This variable does not define an object but can refer to one.

    // Declare reference to an object of class Box
    Box mybox;
    コピーしました。

    • Instantiation and Initialization: Use the new operator to create an actual object and assign it to the variable. The new operator dynamically allocates memory for the object and returns a reference to it. This reference is then stored in the variable.

    // Instantiate and initialize via the new operator
    mybox = new Box();
    コピーしました。

    Here is a complete example:

    class Box {
    double width;
    double height;
    double depth;
    }

    public class Test {
    public static void main(String[] args) {
    // Declare and instantiate a Box object
    Box mybox = new Box();
    mybox.height = 10;
    System.out.println(mybox.height); // Output: 10.0
    }
    }
    コピーしました。
    What's really the point of the 'new' operator i…

    "The new operator instantiates a class by allocating memory for a new object and returnin…

    Stack Overflow
    How does a new operator work in JavaScript?
    When you create a new object, memory is allocated using operator new function and then the constructor is invoked to initialize the memory. Here, The new operator does both the allocation and the initialization, where as the operator new only does the allocation. Let us see how these both work individually. new keyword
    geeksforgeeks.org
    Qiita
    https://qiita.com/joshua_kanae/items/eb2bf22e038f1867846a
    Javaの演算子、new - Qiita
  1. GeeksForGeeks
    https://www.geeksforgeeks.org › java › n…この結果を翻訳する

    new operator in Java - GeeksforGeeks

    2018年5月30日 · The new operator instantiates a class by dynamically allocating (i.e, allocation at run time) memory for a new object and returning a reference to …

  2. Stack Overflow
    https://stackoverflow.com › questionsこの結果を翻訳する

    What's really the point of the 'new' operator in Java?

    2025年6月6日 · "The new operator instantiates a class by allocating memory for a new object and returning a reference to that memory. The new operator also invokes the object constructor."

    コード サンプル

    class A {
      A() { }
      static A A() { return new A(); }
      static A B() { return new A(); }
    }...
    stackoverflow についてさらに表示
    フィードバック
    ありがとうございました!詳細をお聞かせください
    java - How does the new operator create a new object? - Stack Overflow2017年9月22日
    java - What does the `new` keyword do?2012年12月17日
    Difference between new operator in C++ and new operator in java
    What does the 'new' keyword actually do in Java, and should I avoid ...
    その他の検索結果を表示
  3. W3School
    https://www.w3schools.com › java › ref_keyword_new.aspこの結果を翻訳する

    Java new Keyword - W3Schools

    The new keyword creates new objects. Read more about objects in our Java Classes/Objects Tutorial. Java Keywords. Well organized and easy to understand Web building tutorials with lots of examples …

  4. 他の人も質問しています
    フィードバック
  5. Qiita
    https://qiita.com › joshua_kanae › items

    Javaの演算子、new - Qiita

    2024年2月14日 · new演算子はクラスなどの枠組みからコードで使用する実体を呼び出す為に必要となります。 その為、クラスを扱う際に、宣言した変数がクラスなのか、インスタンスなのかを書き手 …

  6. oracle.com
    https://docs.oracle.com › javase › tutorial › java › javaOO › o…この結果を翻訳する

    Creating Objects (The Java™ Tutorials > Learning the Java ... - Oracle

    • The new operator instantiates a class by allocating memory for a new object and returning a reference to that memory. The newoperator also invokes the object constructor. The newoperator requires a single, postfix argument: a call to a constructor. The name of the constructor provides the name of the class to instantiate. The newoperator returns a ...
    docs.oracle.com でさらに表示
  7. TutorialsPoint
    https://www.tutorialspoint.com › the-new-operator-in-javaこの結果を翻訳する

    The new operator in Java - Online Tutorials Library

    The new operator is used in Java to create new objects. It can also be used to create an array object. Let us first see the steps when creating an object from a class − Declaration − A variable declaration with …

  8. antosh.in
    https://java.antosh.in › new-operator-in-java.htmlこの結果を翻訳する

    New Operator in Java - Antosh

    2024年2月3日 · In summary, the `new` operator is a fundamental part of Java's memory allocation and object creation process. It is essential for creating instances of classes and allocating memory for …

  9. IT用語辞典 e-Words
    https://e-words.jp › new演算子.html

    new演算子とは - IT用語辞典 e-Words

    new演算子（new operator）とは、オブジェクト指向プログラミング言語で用いられる演算子の一つで、新しいインスタンスを作成するものです。 本記事では …

  10. DataCamp
    https://www.datacamp.com › doc › java › newこの結果を翻訳する

    new Keyword in Java: Usage & Examples - DataCamp

    Learn how the `new` keyword in Java dynamically allocates memory for objects, enabling class instantiation. Explore syntax, examples, and best practices for effective object-oriented programming …

  11. javaspring.net
    https://www.javaspring.net › blog › difference-between-ne…この結果を翻訳する

    Difference Between new Operator in C++ and Java: Lifecycle

    2025年11月28日 · In this blog, we’ll dive deep into the new operator in C++ and Java, exploring their lifecycle management, memory allocation mechanisms, and how they handle allocation failures.

コンテンツは AI を使用して生成されました。詳細情報