Question

我有一个班级和两个实例。我想制作一些对象的副本。

public class Testing{

    String name;
    String subject;

}

Testing test1 = new Testing();
test1.setName("myName");
test1.setSubject("mySubject");

Testing test2 = test1; 
test1.setName("newName");
test1.setSubject("newSubject");

这是输出。

Printing test1
Name: newName
Subject: newSubject

Printing test2
Name: newName
Subject: newSubject

我想要的是test1保留其名称，同时让test2修改其余成员，以便当test2修改任何变量时，它会反映在test1中（名称除外）。反正有没有实现这个功能？

期望的输出：

Printing test1
Name: myName
Subject: newSubject

Printing test2
Name: newName
Subject: newSubject

Answer 1

您需要将其拆分为两个类。 test1和test2将需要是包含另一个在它们之间共享的对象的不同对象。在下面的代码中，我称之为共享对象Details。

<强> Testing

class Testing {

    String name;
    final Details details;

    private Testing(Details details) {
        this.details = details;
    }

    Testing() {
        this(new Details());
    }

    Testing copy() {
        return new Testing(details);
    }

    void setName(String name) {
        this.name = name;
    }

    void setSubject(String subject) {
        this.details.subject = subject;
    }

    String asString() {
        return String.format("Name: %s\n%s", name, details.asString());
    }
}

<强> Details

class Details {

    String subject;

    String asString() {
        return String.format("Subject: %s", subject);
    }
}

测试跑步者

public class Foo {

    public static void main(String[] args) throws Exception {

        Testing test1 = new Testing();
        test1.setName("myName");
        test1.setSubject("mySubject");

        Testing test2 = test1.copy();
        test2.setName("newName");
        test2.setSubject("newSubject");

        System.out.println(String.format(
            "Printing test1\n%s\n\nPrinting test2\n%s",
            test1.asString(),
            test2.asString()
        ));
    }
}

测试输出

Printing test1
Name: myName
Subject: newSubject

Printing test2
Name: newName
Subject: newSubject

如何在Java中部分复制对象？

1 个答案: