Java . util . treemap . contains key()和 containsValue()在 Java 中
哎哎哎:# t0]https://www . geeksforgeeks . org/Java-util-tree map-containskey-containsvalue-Java/
Java.util.TreeMap 中有两个 contains()的和变体，本文将对这两个变体进行讨论。
1。containskey(对象 o) : 如果映射包含指定键的映射，则返回 true。
Parameters:
o : The key which will be tested whether present or not.
Return Value:
Returns true if there is a mapping for the given key.
Exception:
ClassCastException : This is thrown if the given key cannot be compared
with the keys currently in the map.
NullPointerException : This is thrown if the specified key is null.
// Java code to demonstrate the working
// of containsKey()
import java.io.*;
import java.util.*;
public class containsKey {
public static void main(String[] args)
{
// Declaring the tree map of Integer and String
TreeMap<Integer, String> treemap = new TreeMap<Integer, String>();
// assigning the values in the tree map
// using put()
treemap.put(2, "two");
treemap.put(7, "seven");
treemap.put(3, "three");
treemap.put(6, "six");
treemap.put(9, "nine");
// Use of containsKey
// returns true if mapping for the number is present
System.out.println(treemap.containsKey(6));
System.out.println(treemap.containsKey(4));
}
}
输出:
true
false
2。containsValue(对象 o) : 如果此映射将一个或多个键映射到指定值，则返回 true。
Parameters:
o : This is the value whose presence in this map is to be tested.
Return Value:
Returns true if a mapping to this value exists else false. Exception:
NA
// Java code to demonstrate the working
// of containsValue()
import java.io.*;
import java.util.*;
public class containsValue {
public static void main(String[] args)
{
// Declaring the tree map of Integer and String
TreeMap<Integer, String> treemap = new TreeMap<Integer, String>();
// assigning the values in the tree map
// using put()
treemap.put(2, "two");
treemap.put(7, "seven");
treemap.put(3, "three");
treemap.put(6, "six");
treemap.put(9, "nine");
// Use of containsValue
// returns true if more than one keys are mapped
System.out.println(treemap.containsValue("six"));
System.out.println(treemap.containsValue("four"));
}
}
输出:
true
false
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