Question

我正在尝试编译使用合成的代码。我的目标是实现数据验证代码，以确保在实例化对象时，我使用的分数大于零且小于300.我一直在尝试抛出IllegalArgumentException，但每当我编译整个带有负整数或大于300的整数的东西，我没有收到任何值的错误消息，代码继续正常运行。我只想知道是否有人能引导我朝着正确的方向前进并给我一些建议。这是我提出的代码：

public class ScoresClass 
{
    private int score0;
    private int score1;
    private int score2;
    private int score3;

    public ScoresClass(int a, int b, int c, int d)
    {
        if (score0 < 0 || score0 >= 300)
            throw new IllegalArgumentException("Score must be between 0 - 300");
        if (score1 < 0 || score1 >= 300)
            throw new IllegalArgumentException("Score must be between 0 - 300");
        if (score2 < 0 || score2 >= 300)
            throw new IllegalArgumentException("Score must be between 0 - 300");
        if (score3 < 0 || score3 >= 300)
            throw new IllegalArgumentException("Score must be between 0 - 300");

        this.score0 = a;
        this.score1 = b;
        this.score2 = c;
        this.score3 = d;
    }

    public String toString()
    {
         return String.format("Score 0: %d%n Score 1: %d%n Score 2: %d%n "
            + "Score 3: %d%n", score0, score1, score2, score3);
    }

}

这是我编译用户名的代码：

public class BowlerClass 
{
    private String fName;
    private String lName;
    private ScoresClass value;

    public BowlerClass(String first, String last, ScoresClass amount)
    {
        this.fName = first;
        this.lName = last;
        this.value = amount;
    }

    public String toString()
    {
        return String.format("%s %s%n %s", fName, lName, value);
    }
}

最后是测试代码：

public class BowlerTest {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        ScoresClass a = new ScoresClass(5000, 150, 200, 250);
        BowlerClass b = new BowlerClass("Paul", "McCartney", a);

        System.out.println(b);

    }

}

Answer 1

您的字段score0到score3初始化为0.您必须在检查值是否有效之前设置它们。

或者，这里更合适的方法是检查a，b，c和d是否有效，而不是检查字段。< / p>

Answer 2

使用IllegalArgumentException是一个非常好的主意，但您应该检查参数而不是实例变量。在知道参数正常之前不要修改实例变量，否则仍然会使对象处于不正确的状态。

此外，您可以通过添加参数名称和参数值来增强消息，这将有助于找到错误原因并解决它。

public ScoresClass(int a, int b, int c, int d)
 {
    if (a < 0 || a >= 300)
        throw new IllegalArgumentException("Score 'a' must be between 0 - 300 :" + a);
    if (b < 0 || b >= 300)
       throw new IllegalArgumentException("Score 'b' must be between 0 - 300: " + b);
    if (c < 0 || c >= 300)
       throw new IllegalArgumentException("Score 'c' must be between 0 - 300: " + c);
    if (d < 0 || d >= 300)
       throw new IllegalArgumentException("Score 'd' must be between 0 - 300: " + d);

无法在我的代码中抛出IllegalArgumentException

2 个答案: