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keySet() method is available in java.util package.
keySet()方法在java.util包中可用。
keySet() method is used to get a set of all the existing keys in this IdenityHashMap to be viewed in a Set.
keySet()方法用于获取此IdenityHashMap中所有现有键的集合,以在Set中进行查看。
keySet() method is a non-static method, it is accessible with the class object only and if we try to access the method with the class name then we will get an error.
keySet()方法是一种非静态方法,只能通过类对象访问,如果尝试使用类名访问该方法,则会收到错误消息。
keySet() method does not throw an exception at the time of returning the key set.
返回键集时, keySet()方法不会引发异常。
Syntax:
句法:
public Set keySet();
Parameter(s):
参数:
It does not accept any parameter.
它不接受任何参数。
Return value:
返回值:
The return type of the method is Set, it returns Set view of all the existing keys in this IdenityHashMap.
方法的返回类型为Set ,它返回此IdenityHashMap中所有现有键的Set视图。
Example:
例:
// Java program to demonstrate the example // of Set keySet() method of IdentityHashMap import java.util.*;public class KeySetOfIdentityHashMap { public static void main(String[] args) { // Instantiates a IdentityHashMap object Map < Integer, String > map = new IdentityHashMap < Integer, String > (); // By using put() method is to add // key-value pairs in a IdentityHashMap map.put(10, "C"); map.put(20, "C++"); map.put(50, "JAVA"); map.put(40, "PHP"); map.put(30, "SFDC"); // Display IdentityHashMap System.out.println("IdentityHashMap: " + map); // By using keySet() method is to // return the set of of keys exists // in this IdentityHashMap to be viewed in // a Set Set s = map.keySet(); // Display status System.out.print("map.keySet(): "); System.out.println(s); }}
Output
输出量
IdentityHashMap: {20=C++, 40=PHP, 50=JAVA, 30=SFDC, 10=C}map.keySet(): [20, 40, 50, 30, 10]
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