Question

当我创建另一个Class的ArrayList或TreeMap时，我只能引用最后添加或放置的元素。任何指针/解释/帮助都很受欢迎。

我是Java的新手（经过一段长时间的裁员后回到了它），但[可能是我的[代码]布局可辨别的]来自一个沉重的（主要是Visual）C ++背景。我正在尝试使用Java API，我已经多次使用C ++容器类...

好的，所以我想要一个类的ArrayList来定义一个人＆＃39; ...

package arraylistcontainerprototype;

public class CPerson
{
    private static String mForename;
    private static String mSurname;
    private static int mAge;
    private static int mIndex;

    // public Get/Set() methods encapsulated as normal (one example included but all follow the same code pattern)...

    public String SetForename(mForename)
    {
        String oldForename = mForename;
        this.mForename= mForename;

        return oldForename;

    }

    public String GetForename()
    {
        return mForename;

    }

}

然后我们在另一个＆＃39;容器中使用它。上课，因此： - （请注意，此代码用于对方法进行原型设计，因为我的真实应用程序代码会遇到相同的问题。）

package arraylistcontainerprototype;

import java.util.ArrayList;
import arraylistcontainerprototype.CPerson;

public class CContainer
{
    ArrayList<CPerson> mPersonArray = new ArrayList<CPerson>();

    public int SetArray()
    {
        mPersonArray.clear();
        for(int counter = 0; counter < 5; counter++)
        {
            CPerson person = new CPerson();
            person.SetForename("Harry" + counter);
            person.SetSurname("Royston" + counter);
            person.SetAge(counter);
            person.SetIndex(counter);

            mPersonArray.add(person);

        }

        // then to test the array construction...
        for(int counter = 0; counter < mPersonArray.size(); counter++)
        {
            CPerson person = mPersonArray.get(counter);

            System.out.println(person + "; counter = " + counter);
            System.out.println(person.GetForename() + "; counter = " + counter);
            System.out.println(person.GetSurname() + "; counter = " + counter);
            System.out.println(person.GetAge() + "; counter = " + counter);
            System.out.println(person.GetIndex() + "; counter = " + counter);

        }

    }

}

main（）中的代码驱动＆＃39;以上是： -

CContainer container = new CContainer();
container.SetArray();

The output generated is:-
arraylistcontainerprototype.CPerson@15db9742; counter = 0
Harry4; counter = 0
Royston4; counter = 0
4; counter = 0
4; counter = 0
arraylistcontainerprototype.CPerson@6d06d69c; counter = 1
Harry4; counter = 1
Royston4; counter = 1
4; counter = 1
4; counter = 1
arraylistcontainerprototype.CPerson@7852e922; counter = 2
Harry4; counter = 2
Royston4; counter = 2
4; counter = 2
4; counter = 2
arraylistcontainerprototype.CPerson@4e25154f; counter = 3
Harry4; counter = 3
Royston4; counter = 3
4; counter = 3
4; counter = 3
arraylistcontainerprototype.CPerson@70dea4e; counter = 4
Harry4; counter = 4
Royston4; counter = 4
4; counter = 4
4; counter = 4
BUILD SUCCESSFUL (total time: 0 seconds)

正如您所看到的，对CPerson类实例的引用似乎没问题但是对“getter”的调用是正确的。产生最后添加的＆＃39;元素的数据。

我在互联网上挖了一遍，在Stackoverflow中，但是看不出为什么这是行为不端。

任何指针都非常感激。非常感谢提前。（如果您有意尝试，上面的代码应该很容易复制。我使用Netbeans，我在Windows10和Linux（Centos / Ubuntu）上得到相同的结果。

其他类的{J} ArrayList

0 个答案: