将 <V extends Comparable<V>> 与整数进行比较

Question

我是泛型的新手，想解决一个小任务。

我想给 class ComparePredicate 两个 "V extends Comparable" 类型的对象，然后检查方法 "isOk" 如果树 "value" 的 int 值 class 在这两个对象之间。我选择 compareTo 方法是因为 Integer 和 V 应该是可比较的类型，但编译器会报错。我认为这只是一个语法问题。

那我要怎么写才正确呢。希望你们能帮助我。感谢您的回答。

Class 比较谓词

public class ComparePredicate<V extends Comparable<V>> implements TreePredicate<V> {

    V minEle;
    V maxEle;

    public ComparePredicate(V minEle, V maxEle) {
        this.minEle = minEle;
        this.maxEle = maxEle;
    }

    @Override
    public boolean isOk(Tree<V> tree) {

        return minEle.compareTo(Integer.valueOf(tree.getValue())) > 0 &&
                maxEle.compareTo(Integer.valueOf(tree.getValue())) < 1;
        //COMPILER ERROR: "The method compareTo(V) in the type Comparable<V> is not applicable for the arguments (Integer)"

        return false;
    }

}

Class 树

public class Tree<T> {
    private int value;
    private final Tree<T> left;
    private final Tree<T> right;

    public Tree(int v, Tree<T> l, Tree<T> r) {
        this.value = v;
        this.left = l;
        this.right = r;
    }

    public int getValue() {
        return this.value;
    }

    public Tree<T> getLeft() {
        return this.left;
    }

    public Tree<T> getRight() {
        return this.right;
    }
}

Answer 1

改变树class

static class Tree<T> {
    private T value;
    private final Tree<T> left;
    private final Tree<T> right;

    public Tree(T v, Tree<T> l, Tree<T> r) {
        this.value = v;
        this.left = l;
        this.right = r;
    }

    public T getValue() {
        return this.value;
    }

    // getters ...

}

还要改isOk()

    @Override
    public boolean isOk(Tree<V> tree) {
        return minEle.compareTo(tree.getValue()) <= 0 &&
                maxEle.compareTo(tree.getValue()) >= 0;
    }

将 <V extends Comparable<V>> 与整数进行比较

Compare <V extends Comparable<V>> to Integer

java

generics

generic-programming

comparable