Question

我写了以下toString（）方法

public String toString() {
    return "Product: "+ this.productName + ", Barcode: " + this.barCode
            + ", Expiration Date: " + this.expirationDate.toString() + ", Customer Price: "
            + this.customerPrice + ", Shops Price: " + this.shopsPrice
            + ", Instore Amount: " + this.inStoreAmount + ", Sale: "
            + (this.sale == null) ? "Not on sale" : + this.sale.toString();
}

但是我使用if语句的方式存在问题。

eclipse: "cannot covert from string to boolean"

Answer 1

连接运算符+的平衡存在问题。另外，我编辑了您的方法如下：

public String toString() {
    return "Product: "+ this.productName + ", Barcode: " + this.barCode
            + ", Expiration Date: " + this.expirationDate.toString() + ", Customer Price: "
            + this.customerPrice + ", Shops Price: " + this.shopsPrice
            + ", Instore Amount: " + this.inStoreAmount + ", Sale: "+ ((this.sale == null) ? "Not on sale" : this.sale.toString());
}

当您编写IF-ELSE短手时，请尝试将所有内容保存在(...)括号中，以便轻松跟踪事物。我不关心其他专业人士对此的看法，但如果这有助于你理解事情，那就这样吧！

Answer 2

这是非法语法

(this.sale == null) ? "Not on sale" : + this.sale.toString()

并且编译错误应该提醒您这个问题。

相反，请使用

((this.sale == null) ? "Not on sale" : this.sale.toString())

我已将整个ternary operator放入括号中以明确。

评估“IF ELSE”速记作为toString（）实现的一部分

2 个答案: