我有个问题。例如:
StringBuilder sb = new StringBuilder();
sb.append("Teacher,");
String s = sb.append(" Good").append("Morning!").toString();
Run Code Online (Sandbox Code Playgroud)
现在,在最后一行中,我创建了两个附加方法的链。我知道每个方法追加方法都会返回内存中字符串的地址(我是对的?对吧?)。所以在第一个中它附加到指向的sb.append地址。sb第一个sb.append在运行时首先执行,但是接下来会发生什么.append?接下来.append是使用第一个追加方法返回的地址还是我错了?这就是我的意思:
第一个追加 ->sb.append(" Good");
第二个追加returnedAddr.append("Morning!");
是这样工作的吗?
例外是java.lang.ClassCastException:org.json.JSONObject$Null无法投射到java.lang.String
Printthis>>>>>>userName=user1&passKey=12345678
POST Response Code :: 200
jsonObj>>>>>>>>>>>>>>>>>>{"response":{"roleTitle":"Parent","roleId":146,"passKey":"12345678","id":1,"userName":"user1"},"errorCode":null,"error":false,"message":null}
Jan 04, 2018 4:33:11 PM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet [spring-dispatcher] in context with path [/balihans] threw exception [Request processing failed; nested exception is java.lang.ClassCastException: org.json.JSONObject$Null cannot be cast to java.lang.String] with root cause
java.lang.ClassCastException: org.json.JSONObject$Null cannot be cast to java.lang.String
at com.swasth.general.controller.SwasthController.postLogin(SwasthController.java:2274)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:221)
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:137)
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:110)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:777)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:706)
at …