Question

我正在尝试在一系列测试后填充ArrayList。它工作正常，但有点太精细了。它将每个值添加到数组列表两次。这是我的代码，我不明白问题从哪里来，因为我只有fullresult.add一次？

public ArrayList<Student> filterClasses (String classe){
        ArrayList<Student> fullresult = new ArrayList<Student>();
        for (int i = 0; i < studentDB.StudentList.size(); i++) {
            int classesSize = studentDB.StudentList.get(i).classes().size()/3;
            for (int j = 0; j < classesSize ; j++){
                if (studentDB.StudentList.get(i).classes().contains(classe)){
                    fullresult.add(studentDB.StudentList.get(i));
                }
            }
        }
        System.out.println(fullresult);
        return fullresult;
    }

解

我不需要第二个for循环：

public ArrayList<Student> filterClasses (String classe){
        ArrayList<Student> fullresult = new ArrayList<Student>();
        for (int i = 0; i < studentDB.StudentList.size(); i++) {
                if (studentDB.StudentList.get(i).classes().contains(classe)){
                    fullresult.add(studentDB.StudentList.get(i));
                }
            }

        System.out.println(fullresult.toString());
        return fullresult;
    }

Answer 1

我真的不明白你为什么这么做

int classesSize = studentDB.StudentList.get(i).classes().size()/3;

所以这里的代码可以完成我认为你想要的东西：

public ArrayList<Student> filterClasses (String classe){
        ArrayList<Student> fullresult = new ArrayList<Student>();
        for (Student student : studentDB ) {
                if (student.classes().contains(classe)){
                    fullresult.add(student);
                }
            }
        }
        System.out.println(fullresult);
        return fullresult;
    }

值添加两次到ArrayList

1 个答案: