Java中的CopyOnWriteArrayList方法的isEmpty()方法
若要检查列表是否为空，请使用isEmpty()方法。如果列表为空，则返回TRUE，否则返回FALSE。
语法如下
boolean isEmpty()
要使用CopyOnWriteArrayList类，您需要导入以下包
import java.util.concurrent.CopyOnWriteArrayList;
以下是isEmpty()在Java中实现CopyOnWriteArrayList类方法的示例
例
import java.util.concurrent.CopyOnWriteArrayList;
public class Demo {
public static void main(String[] args) {
CopyOnWriteArrayList<Integer> arrList = new CopyOnWriteArrayList<Integer>();
arrList.add(30);
arrList.add(40);
arrList.add(60);
arrList.add(70);
arrList.add(90);
arrList.add(100);
arrList.add(120);
System.out.println("CopyOnWriteArrayList = " + arrList);
System.out.println("Is the CopyOnWriteArrayList empty? " + arrList.isEmpty());
}
}输出结果
CopyOnWriteArrayList = [30, 40, 60, 70, 90, 100, 120] Is the CopyOnWriteArrayList empty? False
让我们来看另一个例子
示例
import java.util.concurrent.CopyOnWriteArrayList;
public class Demo {
public static void main(String[] args) {
CopyOnWriteArrayList<Integer> arrList = new CopyOnWriteArrayList<Integer>();
arrList.add(30);
arrList.add(40);
arrList.add(60);
arrList.add(70);
arrList.add(90);
arrList.add(100);
arrList.add(120);
System.out.println("CopyOnWriteArrayList = " + arrList);
System.out.println("Is the CopyOnWriteArrayList empty? " + arrList.isEmpty());
arrList.clear();
System.out.println("Updated CopyOnWriteArrayList = " + arrList);
System.out.println("Is the updated CopyOnWriteArrayList empty? " + arrList.isEmpty());
}
}输出结果
CopyOnWriteArrayList = [30, 40, 60, 70, 90, 100, 120] Is the CopyOnWriteArrayList empty? false Updated CopyOnWriteArrayList = [] Is the updated CopyOnWriteArrayList empty? True