我想在創建新客戶時將客戶的卡號始終設定為-1。
代碼外觀的影像
public Customer(int cardNumber, int yearOfBirth) {
this.cardNumber = cardNumber;
this.yearOfBirth = yearOfBirth;
}
public int getCardNumber() {
return cardNumber;
}
public void setCardNumber(int cardNumber) {
this.cardNumber = cardNumber;
}
uj5u.com熱心網友回復：
這是一種方法。向欄位宣告添加初始化程式。
public class Customer {
private int cardNumber = -1;
private int yearOfBirth;
public Customer(int yearOfBirth) {
this.yearOfBirth = yearOfBirth;
}
public int getCardNumber() {
return cardNumber;
}
public void setCardNumber(int cardNumber) {
this.cardNumber = cardNumber;
}
}
另一種選擇是在建構式中將欄位顯式初始化為其默認值；例如
public Customer(int yearOfBirth) {
this.yearOfBirth = yearOfBirth;
this.cardNumber = -1;
}
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標籤：爪哇