Java 示例 - 使用方法打印数组

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  问题描述

  如何使用 instanceOf 关键字显示对象类？
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  解决方案

  此示例使 displayObjectClass() 方法显示在此方法中作为参数传递的对象的类。

  
  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());
     }
  }
  

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  结果

  上面的代码示例将产生以下结果。

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