Question

我试图将参数传递给构造函数但是我被困在方法中用于arraylist的内容。构造：

public Company(int companyid,String companyname, String companyowner, String startdate, String description,
             ArrayList<String> departments) {
    this.companyid=companyid;
    this.companyname = companyname;
    this.companyowner = companyowner;
    this.startdate = startdate;
    this.description = description;
    this.departments = departments;
}

在方法中调用参数：

Company company = new Company(obj.getInt("companyID"),obj.getString("comapnyName"),obj.getString("companyOwner"),obj.getString("companyStartDate"),obj.getString("companyDescription"),obj.getString("companyDepartments"));
company.setCompanyid(obj.getInt("companyID"));
company.setCompanyname(obj.getString("comapnyName"));
company.setCompanyowner(obj.getString("companyOwner"));
company.setStartdate(obj.getString("companyStartDate"));
company.setDescription(obj.getString("companyDescription"));


// Genre is json array
JSONArray companydept = obj.getJSONArray("companyDepartments");
ArrayList<String> departments = new ArrayList<String>();
for (int j = 0; j < companydept.length(); j++) {
    departments.add((String) companydept.get(j));
}
company.setDepartments(departments);

我很困惑在方法中使用什么。预期的参数是Arraylist但是方法中使用的实际参数是String我不知道在那里使用什么。

Answer 1

你很亲密。

在公司的构造函数之前移动以下代码（在您调用新公司之前）。

JSONArray companydept = obj.getJSONArray("companyDepartments");
ArrayList<String> departments = new ArrayList<String>();
for (int j = 0; j < companydept.length(); j++) {
    departments.add((String) companydept.get(j));
}

并致电：

Company company = new Company(obj.getInt("companyID"),obj.getString("comapnyName"),obj.getString("companyOwner"),obj.getString("companyStartDate"),obj.getString("companyDescription"),obj.getString("companyDepartments"), departments);

Answer 2

您有几个选择：

1）您可以从ArrayList<String> departments构造函数中删除Company参数，并像现在一样拥有company.setDepartments(departments); setter。

2）首先创建ArrayList<String> departments，然后将其传递给构造函数：

// Genre is json array
JSONArray companydept = obj.getJSONArray("companyDepartments");
ArrayList<String> departments = new ArrayList<String>();
for (int j = 0; j < companydept.length(); j++) {
     departments.add((String) companydept.get(j));
}

Company company = new Company(obj.getInt("companyID"),
                              obj.getString("comapnyName"),
                              obj.getString("companyOwner"),
                              obj.getString("companyStartDate"),
                              obj.getString("companyDescription"),
                              departments); // <--- Pass the ArrayList here

3）让公司构造函数通过传递ArrayList来构建JSONArray。

public Company(int companyid,String companyname, 
               String companyowner, String startdate, 
               String description, JSONArray companydept) {
     this.companyid=companyid;
     this.companyname = companyname;
     this.companyowner = companyowner;
     this.startdate = startdate;
     this.description = description;

    // build it in the constructor here:
    this.departments = new ArrayList<String>();
    for (int j = 0; j < companydept.length(); j++) {
         departments.add((String) companydept.get(j));
    }  
}

无法在java中使用arraylist参数

2 个答案: