如何在 Java 中使用 instanceOf 关键字显示 Object 类

问题描述

如何使用 instanceOf 关键字显示 Object 类?

解决方案

此示例使用 displayObjectClass() 方法显示作为参数传入此方法的 Object 的类。

import java.util.ArrayList;
import java.util.Vector;

public class Main { 
   public static void main(String[] args) {
      Object testObject = new ArrayList();
      displayObjectClass(testObject);
   }
   public static void displayObjectClass(Object o) {
      if (o instanceof Vector) System.out.println(
         "Object was an instance of the class java.util.Vector");
      else if (o instanceof ArrayList) System.out.println(
         "Object was an instance of the class java.util.ArrayList");
      else System.out.println("Object was an instance of the " + o.getClass());
   }
}

结果

上述代码示例将产生以下结果。

Object was an instance of the class java.util.ArrayList