泛型类概述

• 把泛型定义在类上

  定义格式

• public class 类名<泛型类型1,…>

  注意事项

• 泛型类型必须是引用类型 ```java class GenericTool { private Q q;

  public Q getObj() { return q; }

  public void setObj(Q q) { this.q = q; }

}

```java
    public static void main(String[] args) {
        GenericTool<String> tool = new GenericTool<>();
        //tool.setObj(1);//编译错误
        tool.setObj("a");
        String obj = tool.getObj();
        System.out.println(obj);//a
        GenericTool<Student> tool2 = new GenericTool<>();
        tool2.setObj(new Student("axin",20));
        Student obj1 = tool2.getObj();
        System.out.println(obj1);//Person [name=axin, age=20]
    }