Java从其他类创建ArrayList的实例

Question

情况是这样的:

头等舱:

class Something {
    List<Object> names;
    public Something(){
       this.names = new ArrayList<Object>();    
    }
}

第二节课我尝试做类似的事情但它不起作用:

class Main {
    public static void main(String[] args){
        Something names = new Something();
        ...
        for(Object name: names){
           ...
        }
    }
}

它说我不能遍历“名称”，为什么？我做错了什么？

Answer 1

您可能打算在 您的 Something 类中迭代列表:

public static void main(String[] args){
    Something something = new Something();
    // then assign something.names to something
    ...
    for (Object name: something.getNames()) {
        // do something
    }
}

因此，您可能希望在您的类中为 names 列表公开一个 getter 和 setter:

class Something {
    List<Object> names;

    public Something() {
        this.names = new ArrayList<Object>();    
    }

    public List<Object> getNames() {
        return names;
    }

    public void setNames(List<Object> names) {
        this.names = names;
    }
}