Question

我写了这段代码：

public class ArraLists {
    public static void main(String[] args) {
        ArrayList<Amphitheater> amphitheaters= new ArrayList<Amphitheater>();

            Amphitheater a1 = new Amphitheater("Amph 2");
            Amphitheater a2 = new Amphitheater("Amph 3"); 
            Amphitheater a3 = new Amphitheater("Amph 8");
            Amphitheater a4 = new Amphitheater("Amph 9");
            Amphitheater a5 = new Amphitheater("Amph 11");
            Amphitheater a6 = new Amphitheater("Amph 10");
            Amphitheater a7 = new Amphitheater("Amph 12");
            Amphitheater a8 = new Amphitheater("Amph 13");

            Course cC1 = new Course("Math","M123");

            amphitheaters.add(a1);
            amphitheaters.add(a2);
            amphitheaters.add(a3);
            amphitheaters.add(a4);
            amphitheaters.add(a5);
            amphitheaters.add(a6);
            amphitheaters.add(a7);
            amphitheaters.add(a8);

            DateExamination d1= new DateExamination("03 May",amphitheaters);
            DateExamination d2= new DateExamination("04 May",amphitheaters);

            ArrayList<Amphitheater> amph1= d1.getAmphitheaters();
            ArrayList<Amphitheater> amph2= d2.getAmphitheaters();

            amph2.get(1).addCourse(1,cC1);

            System.out.println("Amphitheaters of D1");
            for(Amphitheater a: amph1) {
               System.out.println(a.getName());
               System.out.println(a.getAvailableHours());
            }

            System.out.println("Amphitheaters of D2");

            for(Amphitheater a: amph2) {
              System.out.println(a.getName());
              System.out.println(a.getAvailableHours());
            }

            System.out.println("\n\nList of Amphitheaters that I created in Main.");

            for(Amphitheater a: amphitheaters) {
              System.out.println(a.getName());
              System.out.println(a.getAvailableHours());
            }   
      }
}


public class Course {

    private String name;
    private String id;

    private ArrayList<Amphitheater> amphitheaters= new ArrayList<Amphitheater>();
    private ArrayList<Integer> hours= new ArrayList<Integer>();

    public Course(String name, String id){
        this.name=name;
        this.id=id;
    }

    public void addAmphitheater(Amphitheater amphitheater,int hour){
        amphitheaters.add(amphitheater);
        hours.add(hour);
    }
}




public class Amphitheater{

    private String name;
    private HashMap<Integer,Boolean> availableHours=new HashMap<Integer,Boolean>(); //Hour,Available
    private HashMap<Integer,Course> courses= new HashMap<Integer,Course>(); //Hour,Course

    public Amphitheater(String name){
        this.name=name;
        for(int i=0; i<5; i++){
           availableHours.put(i,true);
           courses.put(i,null);
        }
    }
    public boolean isHourAvailable(Integer hour){
        return availableHours.get(hour);
    }

    public ArrayList<Integer> getAvailableHours(){
        ArrayList<Integer> avHours= new ArrayList<Integer>();
        for(int i=0; i<5; i++){
            if(availableHours.get(i))
               avHours.add(i);
            }
            return avHours;
        }

    public void addCourse(Integer hour,Course course){
        courses.put(hour,course);
        availableHours.put(hour, false);
        course.addAmphitheater(this,hour);

    }

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

    public String getName(){
        return name;
    }

}






public class DateExamination{

    private ArrayList<Amphitheater> amphitheaters;
    private String name;

    public DateExamination(String name,ArrayList<Amphitheater> amphitheaters) {
        this.name=name;
        this.amphitheaters=amphitheaters;
    }

    public ArrayList<Amphitheater> getAmphitheaters(){
        return amphitheaters;
    }

}

我作为参数传递给DateExamination对象ArrayList与圆形剧场。

问题是，当我将值更改为d1（DateExamination）的圆形剧场时，相同的值会自动更改为d2的圆形剧场（DateExamination ）。

此外，我在ArrayList中创建的Main也已更改。我认为所有ArrayList都引用了相同的对象，但我真的无法理解。

我希望DateExamination的每个物体都有ArrayList个圆形剧场，这些圆形剧场将独立于其他圆形剧场。

我还尝试将此.clone()的{{1}}作为参数传递，但没有结果。

Answer 1

这是因为它们都包含相同的对象，您需要创建每个对象的新实例。

    ArrayList<Amphitheater> amphitheaters= new ArrayList<>();
    ArrayList<Amphitheater> amphitheaters1= new ArrayList<>();

    Course cC1 = new Course("Math","M123");

    amphitheaters.add(new Amphitheater("Amph 2"));
    amphitheaters.add(new Amphitheater("Amph 3"));
    amphitheaters.add(new Amphitheater("Amph 8"));
    amphitheaters.add(new Amphitheater("Amph 9"));
    amphitheaters.add(new Amphitheater("Amph 11"));
    amphitheaters.add(new Amphitheater("Amph 10"));
    amphitheaters.add(new Amphitheater("Amph 12"));
    amphitheaters.add(new Amphitheater("Amph 13"));

    amphitheaters1.add(new Amphitheater("Amph 2"));
    amphitheaters1.add(new Amphitheater("Amph 3"));
    amphitheaters1.add(new Amphitheater("Amph 8"));
    amphitheaters1.add(new Amphitheater("Amph 9"));
    amphitheaters1.add(new Amphitheater("Amph 11"));
    amphitheaters1.add(new Amphitheater("Amph 10"));
    amphitheaters1.add(new Amphitheater("Amph 12"));
    amphitheaters1.add(new Amphitheater("Amph 13"));



    DateExamination d1= new DateExamination("03 May", new ArrayList<>(amphitheaters));
    DateExamination d2= new DateExamination("04 May", new ArrayList<>(amphitheaters1));

这是一个肮脏的黑客来解决它，但如果你只需要这一次，它将适用于你的情况。

更改对象的值，也更改另一个（相同类）对象-Java的相同值

1 个答案: