您好，我正在嘗試獲取隨機 ENUM，但它返回 null，有人可以幫助我我的代碼有什么問題嗎？我試圖獨自修理它，但我放棄了。public class LotteryMachine { protected enum Sings { ONE, TWO, THREE} private static final List<Sings> SINGS_LIST = Collections.unmodifiableList(Arrays.asList(Sings.values())); private static final int SIZE = SINGS_LIST.size(); private static final Random RANDOM = new Random(); Sings randomSing() { return SINGS_LIST.get(RANDOM.nextInt(SIZE)); }}public class Game { private LotteryMachine lotteryMachine = new LotteryMachine(); private LotteryMachine.Sings singOne; private LotteryMachine.Sings singTwo; private LotteryMachine.Sings singThree; private void Lottery(){ this.singOne = lotteryMachine.randomSing(); this.singTwo = lotteryMachine.randomSing(); this.singThree = lotteryMachine.randomSing(); } public void viewLottery(){ System.out.print(singOne + " " + singTwo + " " + singThree); }}
1 回答
慕碼人2483693
TA貢獻1860條經驗 獲得超9個贊
你的問題似乎在這里
private void Lottery(){
this.singOne = lotteryMachine.randomSing();
this.singTwo = lotteryMachine.randomSing();
this.singThree = lotteryMachine.randomSing();
}
這不是構造函數(shù)；相反，它是一個Lottery()被Game類調用但不使用的私有方法。因為從未調用該方法，所以所有singX字段都未初始化（即為空）。將初始化邏輯從所述方法移動到像這樣的字段聲明后，事情應該可以正常工作
private LotteryMachine.Sings singOne = lotteryMachine.randomSing();
private LotteryMachine.Sings singTwo = lotteryMachine.randomSing();
private LotteryMachine.Sings singThree = lotteryMachine.randomSing();
或者聲明Game類的構造函數(shù)如下：
public Game() {
this.singOne = lotteryMachine.randomSing();
this.singTwo = lotteryMachine.randomSing();
this.singThree = lotteryMachine.randomSing();
}
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