如何在内部接口内设置全局变量的值并在 adnroid 中使用接口外的值

Question

有没有办法在接口内部设置全局变量的值并在接口外部使用该值？

这是我的代码示例：

class A{
static ArrayList<String> myList = new ArrayList<>();
public static void main(String[] args) {
    get(new Inter() {
        @Override
        public void callBack(ArrayList<String> list) {
            myList = list; // here list is the textual data from firebase and I want to use it outside
            //  this get function call
        }
    });
    myList.toString(); // I want to use it here. But its value out of the function call was null
                       // but it has the same value with list inside the function call
}
static void get(Inter inter){
    // here I want to get some textual data from firebase into ArrayList of String
    list = array of String from firebase
    inter.callBack(list);
}
interface Inter{
    void callBack(ArrayList<String> list);
}

}

Answer 1

不能在get()调用后直接使用列表，因为get调用是异步的，还没有完成。可以在接口外创建一个方法，将列表作为参数：

public static void main(String[] args) {
    get(new Inter() {
        @Override
        public void callBack(ArrayList<String> list) {
            doSomethingWithList(list);
        }
    });
    
}

private static void doSomethingWithList(List<Sting> list){
    //you code here
}

或者您可以使用 method-reference:

public static void main(String[] args) {
    get(<your class>::doSomethingWithList);
}

private static void doSomethingWithList(List<Sting> list){
    //you code here
}

如何在内部接口内设置全局变量的值并在 adnroid 中使用接口外的值

How to set values of global variable inside inner interface and use the values outside of the interface in adnroid

interface