Question

所以这是我在Main方法中的数组：

ArrayList<String> myarray = new ArrayList<>();
while(scan.hasNextLine()){
    myarray.add(scan.nextLine());
}
scan.close();

我的应用程序有多个线程，我试图在每个线程中使用这个数组（有点大），而不是每次都重新创建数组。主要的想法是以某种方式加载它并准备好被其他类调用。

Answer 1

可能是下面给你一些想法

class Myclass{
    private ArrayList<String> myarray = new ArrayList<>();
    main(){
        //populate the array
    } 
    public ArrayList<String> getList(){
        return myarray;
    }

}

Answer 2

遵循SHG建议：

public MyStaticClass {
    // from your question is not clear whether you need a static or non static List
    // I will assume a static variable is ok
    // the right-hand member should be enough to synchornize your ArrayList
    public static List<String> myarray = Collections.synchronizedList(new ArrayList<String>());

    public static void main(String[] args) {
        // your stuff (which contains scanner initialization?)

        ArrayList<String> myarray = new ArrayList<>();
        while(scan.hasNextLine()){
            myarray.add(scan.nextLine());
        }
        scan.close();

        // your stuff (which contains thread initialization?)
    }

但如果你真的需要一个非静态变量

public MyClass {

    private final List<String> myarray;

    public MyClass() {
        // the right-hand member should be enough to synchornize your ArrayList
        myarray = Collections.synchronizedList(new ArrayList<String>());
    }

    public void getArray() {
        return myarray;
    }


    public static void main(String[] args) {
        // your stuff (which contains scanner initialization?)

        Myclass myObj = new MyClass();
        List<String> myObjArray = myObj.getArray();
        while(scan.hasNextLine()){
            myObjArray.add(scan.nextLine());
        }
        scan.close();

        // your stuff (which contains thread initialization?)
    }

有关静态与非静态字段的详细信息，请查看Oracle documentation（基本上，您将需要或不需要MyClass个实例来获取myarray访问权限，但您将或者不会，在JVM中可以有不同的列表。）

JAVA - 在main方法中创建一个Array List，并在其他类中使用它而不重新创建它

2 个答案: