java中字符串的自定义异常

如何创建自定义异常以确定字符串是否正确！=1. 到目前为止，这就是我所拥有的，但我不确定这是否接近正确

我正在尝试编程一个纸牌游戏，我想为它抛出一个异常

if (rank.length() != 1) {
        return;
    }

/**
 * Name mutator.
 *
 * Business rules: - should be in the range A, 1, ..., 9, T, J, Q, K
 *
 * @param rank the rank to set
 */
public void setRank(String rank) {
    // make sure the rank isn't null
    if (rank == null) {
        throw new NullPointerException ("Rank is null"); 
    }
    // make sure the rank isn't too long or too short
    if (rank.length() != 1) {
        return;
    }
    rank = rank.toUpperCase();
    // check if the rank is one of the allowed ones
    if ("A23456789TJQK".contains(rank)) {
        this.rank = rank;
        // is this an ace?
        if (rank.equals(ACE)) {
            this.value = 1;
        } else // perhaps it is a face card?
        if ((TEN + JACK + QUEEN + KING).contains(rank)) {
            this.value = 10;
        } else {
            // it must be a regular card
            this.value = Integer.parseInt(rank);
        }
    }
}

所以，我想有一个例外

public class StringLengthException extends Exception{


  public StringLengthException () {}


  public StringLengthException (String message)
  {
     super(message);
  }

}

这是我试图为其编写异常的类

if (rank.length() != 1) {
        return;
    }

/**
 * Name mutator.
 *
 * Business rules: - should be in the range A, 1, ..., 9, T, J, Q, K
 *
 * @param rank the rank to set
 */
public void setRank(String rank) {
    // make sure the rank isn't null
    if (rank == null) {
        throw new NullPointerException ("Rank is null"); 
    }
    // make sure the rank isn't too long or too short
    if (rank.length() != 1) {
        return;
    }
    rank = rank.toUpperCase();
    // check if the rank is one of the allowed ones
    if ("A23456789TJQK".contains(rank)) {
        this.rank = rank;
        // is this an ace?
        if (rank.equals(ACE)) {
            this.value = 1;
        } else // perhaps it is a face card?
        if ((TEN + JACK + QUEEN + KING).contains(rank)) {
            this.value = 10;
        } else {
            // it must be a regular card
            this.value = Integer.parseInt(rank);
        }
    }
}

---

您可以做的是检查字符串的长度是否等于1，如果是，则抛出异常：

String str = "...";

if (str.length() == 1)
    throw new StringLengthException();

您必须将其放入一个方法中：

public void someOperationWithStrings(String str) throws StringLengthException {
    if (str.length() == 1)
        throw new StringLengthException();
}

---

不要忘记，如果在方法内部引发异常，则必须声明该方法引发该异常。

异常情况发生时，将引发包含信息的异常。当某些操作正在进行时，您需要找出异常情况。就像您的情况一样，字符串长度不等于1。 因此，您的代码应该如下所示：

if (yourstring.length != 1){
    throw new StringLengthException();
    }

此外，异常还应包含消息，以便更容易识别原因

if (yourstring.length != 1){
    throw new StringLengthException("String length is not equal to 1: String is:" + yourstring);
    }

---

你的课程很好，你现在唯一要做的就是使用它：

public void doSomething (String rank) throws StringLengthException {
    if (rank.length()!=1)
        throw new StringLengthException("rank is not of size 1");

    // Do stuff
}

然后像这样调用该方法：

try {
    String rank = "A";
    doSomething(rank);
} catch (StringLengthException sle) {
    sle.printStackTrace();
}

---

但是，如果您只想存储一个字符，为什么不使用

字符

或

字符

类型？

您正在查找

IllegalArgumentException

？