java - 具有初始值的 Class 实例的静态数组列表

Question

我用一个静态数组列表创建了一个 Coin 类，它存储了创建的类的每个实例，但是我需要用一个初始实例启动该列表，而且我还没有想出如何在不添加它两次的情况下做到这一点(因为冗余代码)，有什么建议吗？

public class Coin {
    private static ArrayList<String> coinNames = new ArrayList<>();
    private static ArrayList<String> coinAbbreviations = new ArrayList<>(Arrays.asList("CLP"));
    private static ArrayList<Coin> coins =
            new ArrayList<>(Arrays.asList(new Coin("Pesos chilenos", "CLP", 1f, "CLP")));
    private static HashMap<String,Float> exchangeRates;
    private String coinName;
    private String coinAbbreviation;
    private Float coinValue;
    private String unit;


    public Coin(String coinName, String coinAbbreviation, Float coinValue, String unit) {
        assert !coinAbbreviations.contains(coinAbbreviation) : "Coin abbreviation already used";
        assert coinAbbreviations.contains(unit) : "Coin unit non existent.";
        assert !coinNames.contains(coinName) : "Coin name already used.";
        this.coinName = coinName;
        this.coinAbbreviation = coinAbbreviation;
        this.coinValue = coinValue;
        this.unit = unit;

        coins.add(this);
    }
}

Answer 1

如果您坚持使用可变静态变量——这样做通常根本不是一个好主意——您可以这样做

private static ArrayList<Coin> coins =
        new ArrayList<>();

static {
  new Coin("Pesos chilenos", "CLP", 1f, "CLP");
}

...立即将元素添加到列表中。