搜索并添加到数组列表

Question

what i'm trying to do with the method below is look for a specific student in an array list that where the name and unique number(HUN) match the key and keyInt respectively. Once that student is found it should add to the local array list returnStudent and return it. However the line returnStudent.add(student(i)); is giving me an error and i can't figure out how to fix it,i need it to add the specific student to the local array list.

public ArrayList<Student1> searchByKey(String key, int keyInt)
{
    ArrayList<Student1> returnStudent = new ArrayList<Student1>();
    Student1 student = new Student1(key);
    int i = 0;
    while(i <= students.size())
    {
        if(student.getName().equals(key) && student.getHUN() == keyInt)
        {
            return Student.add(student(i));
        }
        i=i+1;
    }
    return returnStudent;
}

Thanks in advance.

Answer 1

Change

returnStudent.add(student(i)); 

to

returnStudent.add(student); // student is the element

to add to a specific index, use -

returnStudent.add(i, student); // i is the index to add element at

Note - since you have initialized i=0 you shall iterate through i < students.size() or you might end up accessing get(i) on the list for the value that doesn't exist (base indexed to 0).

---

The other way to do what you are trying to achieve is using Java8 as -

ArrayList<Student1> students = new ArrayList<>();

public ArrayList<Student1> searchByKey(String key, int keyInt) {
    ArrayList<Student1> returnStudent = new ArrayList<>();
    Student1 student = new Student1(key);
    students.forEach(element -> {
        if (element.getName().equals(key) && element.getHUN() == keyInt) {
            returnStudent.add(element);
        }
    });
    return returnStudent;
}

Answer 2

You loop through students . But add student(i) . Note the s at the end. Change the add to students(i) .

Answer 3

Assuming students is an ArrayList with prepopulated data, you can do the following.

public ArrayList<Student1> searchByKey(String key, int keyInt) {
    ArrayList<Student1> returnStudent = new ArrayList<Student1>();

    for(Student1 student1 : students) {
        if(student1.getName().equals(key) && student1.getHUN() == keyInt) {
            returnStudent.add(student1);
        }
    }

    return returnStudent;
}

I have changed the while loop to foreach loop to make it look simpler and easily understandable.