使用Collections.frequency检查Java中元素的频率
用Java创建列表-
List< String >list = Arrays.asList("P","Q","R","P","T","P","U","V","W","X","W" );现在，假设您要获取元素P的频率。为此，请使用Collections.frequency()方法-
Collections.frequency(list, "P");
如上所示，我们也可以找到任何字母的出现-
Collections.frequency(list, "T");
示例
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
public class Demo {
public static void main(String[] args) {
List<String>list = Arrays.asList("P","Q","R","P","T","P","U","V","W","X","W" );
int checkOccurrence = Collections.frequency(list, "P");
System.out.println("Occurrence of P = " + checkOccurrence);
checkOccurrence = Collections.frequency(list, "W");
System.out.println("Occurrence of W = " + checkOccurrence);
checkOccurrence = Collections.frequency(list, "T");
System.out.println("Occurrence of T = " + checkOccurrence);
}
}输出结果
Occurrence of P = 3 Occurrence of W = 2 Occurrence of T = 1