No enclosing instance of type XXX is accessible.

淩亂°似流年 2022-05-26 06:18 48阅读 0赞

一个类LambdaChapter3 中有另一个类Artist (外部类和内部类), 如果使用new 的方式创建内部类的对象,会报错:No enclosing instance of type LambdaChapter3 is accessible.  
报错信息:

No enclosing instance of type LambdaChapter3 is accessible. Must qualify the allocation with an enclosing instance of type LambdaChapter3 (e.g. x.new A() where x is an instance of LambdaChapter3 ).

**原因**:  
内部类是动态的（无static关键字修饰），而main方法是静态的，普通的内部类对象隐含地保存了一个引用，指向创建它的外围类对象，所以要在static方法（类加载时已经初始化）调用内部类的必须先创建外部类。

**解决方法:**  
创建内部类对象应该:  
方法1:外部类对象.内部类对象 (保证外部类对象先于内部类对象出现)

DanymicTest test = new StaticCallDynamic().new DanymicTest();

其中StaticCallDynamic为外部类，DanymicTest为内部动态类；  
方法2:  
如果将**内部类修改为静态类**，可以在main中直接创建内部类实例。

//外部类LambdaChapter3 
    public class LambdaChapter3 {
    
        public static void main(String[] args) {
            ArrayList<Artist> allArtists  = new ArrayList();
            //Artist artist = new LambdaChapter3().new Artist("zhangsan", "London");
            Artist artist = new Artist("zhangsan", "London");
            allArtists.add(artist);
            artistNationnal_java8(allArtists);
        }
    
        //内部类 Artist
        class  Artist {
            private String name;
            private String city;
    
    
            public Artist(String name, String city) {
                super();
                this.name = name;
                this.city = city;
            }
    
    
            public String getName() {
                return name;
            }
    
    
            public void setName(String name) {
                this.name = name;
            }
    
    
            public String getCity() {
                return city;
            }
    
    
            public void setCity(String city) {
                this.city = city;
            }
    
    
            public boolean isFrom(String string) {
                return string.equals("London");
            }
    
    
            public void setIsFrom(String isFrom) {
                this.city = isFrom;
            }
    
        }
    
    }

![这里写图片描述][70]

[70]: /images/20220526/60276c26dd73440ca8ed3ff2d4b6651a.png