英文:
Undefined arguments in return with INT
问题
以下是翻译好的代码部分：
public final class PhpArray extends AbstractMap{private TreeMap t;private HashMap m;public PhpArray() {this.t = new TreeMap(Request.PHP_ARRAY_KEY_COMPARATOR);this.m = null;}@Overridepublic Object put(final Object key, final Object value) {if (this.m != null) {return this.m.put(key, value);}try {return this.t.put(key, value);}catch (ClassCastException e) {this.m = new HashMap(this.t);this.t = null;return this.m.put(key, value);}}@Overridepublic Set entrySet() {if (this.t != null) {return this.t.entrySet();}return this.m.entrySet();}public int arraySize() {if (this.t == null) {throw new IllegalArgumentException("The passed PHP \"array\" is not a sequence but a dictionary");}if (this.t.size() == 0) {return 0;}return 1 + this.t.lastKey();}}
请注意，为了保持代码的完整性和一致性，我已经将代码中的注释和错误消息翻译成了英文。如果您需要更多帮助或解释，请随时提问。
英文:
i have the code like this when i create it like this
public final class PhpArray extends AbstractMap{private TreeMap t;private HashMap m;public PhpArray() {this.t = new TreeMap(Request.PHP_ARRAY_KEY_COMPARATOR);this.m = null;}@Overridepublic Object put(final Object key, final Object value) {if (this.m != null) {return this.m.put(key, value);}try {return this.t.put(key, value);}catch (ClassCastException e) {this.m = new HashMap(this.t);this.t = null;return this.m.put(key, value);}}@Overridepublic Set entrySet() {if (this.t != null) {return this.t.entrySet();}return this.m.entrySet();}public int arraySize() {if (this.t == null) {throw new IllegalArgumentException("The passed PHP \"array\" is not a sequence but a dictionary");}if (this.t.size() == 0) {return 0;}return 1 + this.t.lastKey();}}
but when i update my project i got error in the code
return 1 + this.t.lastKey();
the error is an arguments + is undefined.. why like that ? and how to fix the problem ?
答案1
得分: 1
TreeMap是一个泛型类，但在您问题中的代码中，您使用了没有类型参数的形式。这意味着您代码中的这行：
private TreeMap t;
实际上等同于这行：
private TreeMap<Object, Object> t;
换句话说，t.lastKey()返回一个Object，而运算符+不能用于Object，因为Object不是一个数字。
也许您想要调用size()方法而不是lastKey()方法？
也许这个教程会有帮助？
英文:
TreeMap is a generic class but in the code in your question you have used it without type parameters. This means that this line of your code:
private TreeMap t;
is essentially this:
private TreeMap<Object, Object> t;
In other words t.lastKey() returns an Object and the operator + can't be used with Object because an Object is not a number.
Perhaps you meant to call method size() rather than method lastKey()?
Perhaps this tutorial will help?
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