Question

希望你做得很好

我在向ArrayList添加对象时遇到问题我需要你的帮助来解决这个问题每次当我要向selectedContacts ArrayList添加内容时，我得到了nullPointerException

ArrayList<ContactInfo> selectedContacts = new ArrayList<>();
    public ArrayList<ContactInfo> getSelectedContacts()
        {
            int i = 0;
            while (contacts.get(i).isCheck()==true)
            {
                ContactInfo info = contacts.get(i);
                if(info != null)
                    selectedContacts.add(info);
                i++;
            }
            return selectedContacts;
        }

ContactInfo.Java

public class ContactInfo {
    String name;
    String number;
    String email;
    boolean check;

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public void setCheck(boolean check) {
        this.check = check;
    }

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

    public void setNumber(String number) {
        this.number = number;
    }

    public boolean isCheck() {
        return check;
    }

    public String getName() {
        return name;
    }

    public String getNumber() {
        return number;
    }

}

Answer 1

由于您在selectedContacts方法中返回getSelectedContacts，因此最好在方法中移动ArrayList声明。如;

public ArrayList<ContactInfo> getSelectedContacts()
{
    ArrayList<ContactInfo> selectedContacts = new ArrayList<>();

    int i = 0;
    while (contacts.get(i).isCheck()==true)
    {
        ContactInfo info = contacts.get(i);
        if(info != null)
            selectedContacts.add(info);
        i++;
    }
    return selectedContacts;
}

ArrayList Add Function上的JavaNullPointer异常

1 个答案: