示例代码:实现自然顺序排序 importjava.util.TreeSet;classPersonimplementsComparable<Person>{Stringname;intage;publicPerson(Stringname,intage){this.name=name;this.age=age;}@OverridepublicintcompareTo(Personother){if(this.age!=other.age){returnInteger.compare(this.age,other.age);// 按年龄排序}returnthis...
Exception in thread "main" java.lang.ClassCastException: com.frank.chapter22.TreeSetTest$Goods cannot be cast to java.lang.Comparable [Goods{name='Iphone4S', price=500.0}, Goods{name='Iphone5', price=800.0}, Goods{name='Iphone6S', price=2500.0}, Goods{name='Iphone7S', price=4500.0}, ...
Exception in thread"main"java.lang.ClassCastException: java4interview.Location cannot be cast to java.lang.Comparable 通过查看源码发现,在TreeSet调用add方法时,会调用到底层TreeMap的put方法,在put方法中会调用到compare(key, key)方法,进行key大小的比较;在比较的时候,会将传入的key进行类型强转,所以当我们...
}// java.io.Serializable的读取函数:根据写入方式读出// 先将TreeSet的“比较器、容量、所有的元素值”依次读出privatevoidreadObject(java.io.ObjectInputStream s) throws java.io.IOException, ClassNotFoundException{// Read in any hidden stuffs.defaultReadObject();// 从输入流中读取TreeSet的“比较器”Com...
Exception in thread "main" java.lang.ClassCastException: com.lei.Students cannot be cast to java.lang.Comparable 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 报错了,因为集合里面的是对象,对象不能转换为比较可比较对象。 如果想根据年龄排序,打印出各个对象(toString方法),应该怎么做呢?
Exception in thread "main" java.lang.ClassCastException: com.itheima.p6.Person cannot be cast to java.lang.Comparable at java.util.TreeMap.compare(TreeMap.java:1294) at java.util.TreeMap.put(TreeMap.java:538) at java.util.TreeSet.add(TreeSet.java:255) ...
import java.util.TreeMap; import java.util.TreeSet; public class TreeSetDemo { public static void main(String[] args) { TreeSet<Student> set1 = new TreeSet<Student>(); Student stu1 = new Student("wen",12); Student stu2 = new Student("di",15); ...
java中TreeSet有什么用,举例说明 2.2 TreeSet的用法 TreeSet 二叉查找书,所以结果为升序,任何顺序添加打印结果都为升序。 例:2.2.1 import java.io.*; import java.util.*; public class TestMark_to_win { public static void main(String args[]) {...
从输出结果可以看出，程序抛出“Exception in thread "main" java.lang.ClassCastException: treesetnum.MyNumber cannot be cast to java.lang.Comparable”异常，意思是MyNumber类没有实现Comparable接口，导致进行元素比较时发生错误。在上面的例子代码中，TreeSet集合添加了三个MyNumber对象，添加第一个对象时，Tree...
import java.util.TreeSet; /* Test everything! */ public class NewCareer { public static void main(String[] args) { System.out.println("Let get in a new career!"); TreeSet treeSet = new TreeSet(); treeSet.add(new Cat()); ...