Java \u805a\u5408<\/h1>\n<\/p><\/div>\n

\n \u5982\u679c\u7c7b\u5177\u6709\u5b9e\u4f53\u5f15\u7528\uff0c\u5219\u79f0\u4e3a\u805a\u5408\u3002\u805a\u96c6\u8868\u793aHAS-A\u5173\u7cfb\u3002\u8003\u8651\u4e00\u79cd\u60c5\u51b5\uff0cEmployee\u5bf9\u8c61\u5305\u542b\u8bb8\u591a\u4fe1\u606f\uff0c\u4f8b\u5982id\uff0cname\uff0cemailId\u7b49\u3002\u5b83\u8fd8\u5305\u542b\u4e00\u4e2a\u540d\u4e3aaddress\u7684\u5bf9\u8c61\uff0c\u8be5\u5bf9\u8c61\u5305\u542b\u81ea\u5df1\u7684\u4fe1\u606f\uff0c\u4f8b\u5982\u57ce\u5e02\uff0c\u5dde\uff0c\u56fd\u5bb6\/\u5730\u533a\uff0c\u90ae\u653f\u7f16\u7801\u7b49\uff0c\u5982\u4e0b\u6240\u793a\u3002\n <\/div>\n

class Employee{ \n
 int id; \n
 String name; \n
 Address address;\/\/Address is a class \n
 ... \n
 } \n
<\/code><\/pre>\n<\/p><\/div>\n\n    \u5728\u8fd9\u79cd\u60c5\u51b5\u4e0b\uff0c\u96c7\u5458\u5177\u6709\u5b9e\u4f53\u5f15\u7528\u5730\u5740\uff0c\u56e0\u6b64\u5173\u7cfb\u4e3a\u96c7\u5458HAS-A\u5730\u5740\u3002\n  <\/div>\n\u4e3a\u4ec0\u4e48\u8981\u4f7f\u7528\u805a\u5408\uff1f<\/h2>\n  \u7528\u4e8e\u4ee3\u7801\u53ef\u91cd\u7528\u6027\u3002<\/span> <\/p>\n
\u805a\u5408\u7684\u7b80\u5355\u793a\u4f8b<\/h2>\n   <\/p>\n
\n    \u5728\u6b64\u793a\u4f8b\u4e2d\uff0c\u6211\u4eec\u5728Circle\u7c7b\u4e2d\u521b\u5efa\u4e86Operation\u7c7b\u7684\u5f15\u7528\u3002\n  <\/div>\n\n class Operation{
     int square(int n){
         return <\/span>n*n;
     }
 }
 class Circle{
     Operation op;
  
     \/\/aggregation  double <\/span>pi=3.14;
     double area(int radius){
         op=new Operation();
         int rsquare=op.square<\/span>(radius);
  
         \/\/code reusability (i.e. delegates the method call). return <\/span>pi*rsquare;
     }
     public <\/span>static void <\/span>main(String args[]){
         Circle c=new Circle();
         double result=c.area<\/span>(5);
         System.out.println<\/span><\/span>(result);
     }
 }
 <\/span><\/code><\/pre>\n<\/p><\/div>\n\n   \u8f93\u51fa\uff1a<\/strong>\n  <\/div>\n\n78.5<\/code><\/pre>\n<\/p><\/div>\n\u4ec0\u4e48\u65f6\u5019\u4f7f\u7528\u805a\u5408\uff1f<\/h2>\n  \u5f53\u6ca1\u6709is-a\u5173\u7cfb\u65f6\uff0c\u901a\u8fc7\u805a\u5408\u4e5f\u53ef\u4ee5\u6700\u597d\u5730\u5b9e\u73b0\u4ee3\u7801\u91cd\u7528\u3002<\/span>
\n  \u53ea\u6709\u5728\u5173\u7cfb-a\u5728\u6240\u6d89\u53ca\u5bf9\u8c61\u7684\u6574\u4e2a\u751f\u547d\u5468\u671f\u4e2d\u90fd\u4fdd\u6301\u4e0d\u53d8\u65f6\uff0c\u624d\u5e94\u4f7f\u7528\u7ee7\u627f\u3002\u5426\u5219\uff0c\u805a\u5408\u662f\u6700\u4f73\u9009\u62e9\u3002<\/span> <\/p>\n
\n    Address.java\n  <\/div>\n\n public <\/span>class Address { 
 String city,state,country; 
  
 public <\/span>Address(String city, String state, String country) { 
     this<\/span>.city = city; 
     this<\/span>.state = state; 
     this<\/span>.country <\/span>= country; 
 } 
  
 } 
 <\/span><\/code><\/pre>\n<\/p><\/div>\n\n    Emp.java\n  <\/div>\n\n public <\/span>class Emp {
     int id;
     String name;
     Address address;
     public <\/span>Emp(int id, String name,Address address) {
         this<\/span>.id = id;
         this<\/span>.name = name;
         this<\/span>.address=address;
     }
     void display(){
         System.out.println<\/span><\/span>(id+\" \"<\/span><\/span><\/span>+name);
         System.out.println<\/span><\/span>(address.city+\" \"+address.state+\" \"+address.country);
     }
     public <\/span>static void <\/span>main(String[] args) {
         Address address1=new Address(\"gzb\"<\/span>,\"UP\"<\/span><\/span>,\"india\"<\/span><\/span>);
         Address address2=new Address(\"gno\"<\/span>,\"UP\",\"india\");
         Emp e=new Emp(111,\"varun\"<\/span>,address1);
         Emp e2=new Emp(112,\"arun\"<\/span>,address2);
         e.display<\/span>();
         e2.display<\/span>();
     }
 }
 <\/span><\/code><\/pre>\n<\/p><\/div>\n\n   \u8f93\u51fa\uff1a<\/strong>\n  <\/div>\n\n 111 varun
 gzb UP india
 112 arun
 gno UP india 
 <\/span><\/code><\/pre>\n<\/p><\/div>\n <\/body>
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