TreeMapをjava.lang.Comparableにキャストすることはできません

Treemap Cannot Be Cast Java

 /** * Constructs a new, empty tree map, using the natural ordering of its * keys. All keys inserted into the map must implement the {@link * Comparable} interface. Furthermore, all such keys must be *  mutually comparable : k1.compareTo(k2) must not throw * a ClassCastException for any keys k1 and * k2 in the map. If the user attempts to put a key into the * map that violates this constraint (for example, the user attempts to * put a string key into a map whose keys are integers), the * put(Object key, Object value) call will throw a * ClassCastException. */ public TreeMap() { comparator = null }

 /** * Associates the specified value with the specified key in this map. * If the map previously contained a mapping for the key, the old * value is replaced. * * @param key key with which the specified value is to be associated * @param value value to be associated with the specified key * * @return the previous value associated with key, or * null if there was no mapping for key. * (A null return can also indicate that the map * previously associated null with key.)   *   @throws   ClassCastException if the specified key cannot be compared * with the keys currently in the map  * @throws NullPointerException if the specified key is null * and this map uses natural ordering, or its comparator * does not permit null keys */ public V put(K key, V value) { Entry t = root if (t == null) { // TBD: // 5045147: (coll) Adding null to an empty TreeSet should // throw NullPointerException // // compare(key, key) // type check root = new Entry(key, value, null) size = 1 modCount++ return null } int cmp Entry parent // split comparator and comparable paths Comparatorsuper K> cpr = comparator if (cpr != null) { do { parent = t cmp = cpr.compare(key, t.key) if (cmp <0) t = t.left else if (cmp > 0) t = t.right else return t.setValue(value) } while (t != null) } else { if (key == null) throw new NullPointerException()   Comparable  super K> k = (Comparablesuper K>) key  do { parent = t cmp = k.compareTo(t.key) if (cmp <0) t = t.left else if (cmp > 0) t = t.right else return t.setValue(value) } while (t != null) } Entry e = new Entry(key, value, parent) if (cmp <0) parent.left = e else parent.right = e fixAfterInsertion(e) size++ modCount++ return null }

エラーシナリオ：

package map import java.util.Map import java.util.TreeMap public class TreeMapDemo { public static void main(String[] args) { Map treeMap = new TreeMap() for (int i = 0 i <10 i++) { treeMap.put(i + Math.round(Math.random() * 10), new Staff(i)) } System.out.println(treeMap) System.out.println('result:' + treeMap.containsKey(10)) System.out.println('result:' + treeMap.containsKey(1l)) } } class Staff { private int yearOfWorking public Staff(int yearOfWorking) { this.yearOfWorking = yearOfWorking } @Override public String toString() { return 'Staff{' + 'yearOfWorking=' + yearOfWorking + '}' } }

{5=Staff{yearOfWorking=1}, 7=Staff{yearOfWorking=5}, 9=Staff{yearOfWorking=7}, 10=Staff{yearOfWorking=9}, 11=Staff{yearOfWorking=2}, 13=Staff{yearOfWorking=8}} Exception in thread 'main' java.lang.ClassCastException:  java.lang.Long cannot be cast to java.lang.Integer  at java.lang.Integer.compareTo(Integer.java:35) at java.util.TreeMap.getEntry(TreeMap.java:328) at java.util.TreeMap.containsKey(TreeMap.java:209) at map.TreeMapDemo.main(TreeMapDemo.java:13) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at com.intellij.rt.execution.application.AppMain.main(AppMain.java:140)