Java中的TreeSet floor()方法及示例
java.util.TreeSet
语法:
public E floor(E e)
Java
参数: 此方法将值 e 作为要匹配的参数。
返回值: 这个方法返回小于或等于e的元素中的最大元素,如果没有这样的元素,则返回 null
异常: 如果指定的元素为空并且此设置使用自然排序,或其比较器不允许空元素,则此方法会引发 NullPointerException
下面是说明 floor() 方法的示例。
示例1:
//演示使用floor()方法的Java程序
//对于整数值
import java.util.*;
public class GFG1 {
public static void main(String[] argv) throws Exception
{
try {
// create tree set object
TreeSet<Integer> treeadd = new TreeSet<Integer>();
// populate the TreeSet using add() method
treeadd.add(10);
treeadd.add(20);
treeadd.add(30);
treeadd.add(40);
// Print the TreeSet
System.out.println("TreeSet: " + treeadd);
// getting the floor value for 25
// using floor() method
int value = treeadd.floor(25);
// printing the floor value
System.out.println("Floor value for 25: "
+ value);
}
catch (NullPointerException e) {
System.out.println("Exception thrown : " + e);
}
}
}
Java
TreeSet: [10, 20, 30, 40]
Floor value for 25: 20
Java
示例2: 对于NullPointerException
//演示使用floor()方法的Java程序
//对于NullPointerException
import java.util.*;
public class GFG1 {
public static void main(String[] argv)
throws Exception
{
try {
// create tree set object
TreeSet<Integer> treeadd = new TreeSet<Integer>();
// populate the TreeSet using add() method
treeadd.add(10);
treeadd.add(20);
treeadd.add(30);
treeadd.add(40);
// Print the TreeSet
System.out.println("TreeSet: " + treeadd);
// getting the floor value for null
// using floor() method
System.out.println("Trying to get"
+ " the floor value"
+ " for null");
int value = treeadd.floor(null);
// printing the floor value
System.out.println("Floor value for 25: "
+ value);
}
catch (NullPointerException e) {
System.out.println("Exception thrown : " + e);
}
}
}
Java
TreeSet: [10, 20, 30, 40]
Trying to get the空元素的 floor 值
Exception thrown : java.lang.NullPointerException
Java