Java类型参数不在其范围内

I have a class Zeitpunkt which implements a date with time and in addition a class Suchbaum which represents a binary search tree.

我有一个类Zeitpunkt，它实现了一个带有时间的日期，另外还有一个类Suchbaum，表示一个二叉搜索树。

I want to use a Comparator-Object in Suchbaum to sort a tree by the day of Zeitpunkt, but when I want to create a Suchbaum object, it prints the named error.

我想使用Suchbaum中的Comparator-Object来按Zeitpunkt的日期对树进行排序，但是当我想创建一个Suchbaum对象时，它会打印命名错误。

Zeipunkt

Zeipunkt

public class Zeitpunkt<T> implements Comparable<T>
{
private int jahr;
private int monat;
private int tag;
private int stunden;
private int minuten;
private double sekunden;

public int vergleich(Zeitpunkt a) { ... }

@Override
public int compareTo(T o) {
    if(o instanceof Zeitpunkt)
        return vergleich((Zeitpunkt)o);
    return 0;
}
...
}

Suchbaum

Suchbaum

public class Suchbaum<T extends Comparable<T>> {
private class Element {
    private T daten;
    private Element links;
    private Element rechts;

    public Element(T t) {
        daten = t;
        links = null;
        rechts = null;
    }
}
private Element wurzel;
private Comparator<T> comp;
...
}

Testclass

Testclass

public class BaumTest {
public static void main(String[] args) {

// error in the following line (IntelliJ underlines the first 
// "Zeitpunkt"). Suchbaum<Zeitpunkt<?>> = ... doesn't work either..
// *Completely confused*
Suchbaum<Zeitpunkt> sb = new Suchbaum<>((Zeitpunkt z1, Zeitpunkt z2) -> {
        if(z1.getTag() > z2.getTag())
            return 1;
        else if(z1.getTag() == z2.getTag())
            return 0;
        else
            return -1;
    });
}
}

Any ideas? (the other threads with this topic didn't help me out)

什么好主意吗?(其他关于这个话题的文章对我没有帮助)

1 个解决方案

#1

Seems that you don't want to make your Zeitpunkt class parametrized, you just want it to implement Comparable interface. So change it like this:

似乎您不想让Zeitpunkt类参数化，而只想让它实现可比接口。所以像这样改变它:

public class Zeitpunkt implements Comparable<Zeitpunkt> {
    private int jahr;
    private int monat;
    private int tag;
    private int stunden;
    private int minuten;
    private double sekunden;

    public int vergleich(Zeitpunkt a) {
        return 0;
    }

    @Override
    public int compareTo(Zeitpunkt o) {
        return vergleich(o);
    }
}

Also you need to define a constructor in your Suchbaum class:

还需要在Suchbaum类中定义构造函数:

public Suchbaum(Comparator<T> comp) {
    this.comp = comp;
}

#1