Java AbstractCollection类的isEmpty()方法
isEmpty()AbstractCollection类的方法检查集合是否为空，即它是否具有零个元素。如果Collectionn没有元素，则返回。
语法如下-
public boolean isEmpty()
要使用Java中的AbstractCollection类，请导入以下包-
import java.util.AbstractCollection;
以下是isEmpty()在Java中实现AbstractCollection方法的示例-
示例
import java.util.ArrayList;
import java.util.AbstractCollection;
public class Demo {
public static void main(String[] args) {
AbstractCollection<Object> absCollection = new ArrayList<Object>();
absCollection.add("Laptop");
absCollection.add("Tablet");
absCollection.add("Mobile");
absCollection.add("E-Book Reader");
absCollection.add("SSD");
absCollection.add("HDD");
System.out.println("AbstractCollection = " + absCollection);
System.out.println("Collection is empty? = " + absCollection.isEmpty());
}
}输出结果
AbstractCollection = [Laptop, Tablet, Mobile, E-Book Reader, SSD, HDD] Collection is empty? = false
让我们看另一个例子-
示例
import java.util.ArrayList;
import java.util.AbstractCollection;
public class Demo {
public static void main(String[] args) {
AbstractCollection<Object> absCollection = new ArrayList<Object>();
System.out.println("AbstractCollection = " + absCollection);
System.out.println("Collection is empty? = " + absCollection.isEmpty());
}
}输出结果
AbstractCollection = [] Collection is empty? = true