pointers - Java Object assignment when passing to a method -

-

this question has answer here:

i have following

class test{      public inner x;      public static void main(string[] args){          test t = new test();         t.bar(t.x);      }      public test(){         x = new inner();         system.out.println("x = "+x.val);     }      public void bar(inner a){         x.val = 2;         system.out.println("a = "+a.val);         = new inner(5);         system.out.println("a = "+a.val);         system.out.println("x = "+this.x.val);     }      class inner{         public int val;         public inner(){val=0;}         public inner(int i){val=i;}     } }

i concerned why program tells me class's inner object , passed-in object same, when change passed object new one, not same. thought java passed pointers, , changing pointer location of "a" in bar method likewise change pointer location of "x", passed in.

do want change "a", change "x" it? keyword "new" open new memory, function "bar" inside "x" , "a" pointer different memory, modify "a" not change "x". can try modify "bar" follows:

 public void bar(inner a){     x.val = 2;     system.out.println("a = "+a.val);     //a = new inner(5);     a.val = 5;     system.out.println("a = "+a.val);     system.out.println("x = "+this.x.val); }

Comments

Post a Comment

Popular posts from this blog

java - Run spring boot application error: Cannot instantiate interface org.springframework.context.ApplicationListener -

-
i have spring project , try make use spring boot , run @ embadded tomcat following : https://spring.io/guides/gs/rest-service/ this application //@configuration //@enableaspectjautoproxy @springbootapplication @componentscan(basepackages = "gux.prome") public class application { public static void main(string[] args) { springapplication.run(application.class, args); } } if use maven command: mvn spring-boot:run , project starts fine, need debug , run main method @ intelij, exception occurs: exception in thread "main" java.lang.illegalargumentexception: cannot instantiate interface org.springframework.context.applicationlistener : org.springframework.boot.logging.classpathloggingapplicationlistener @ org.springframework.boot.springapplication.createspringfactoriesinstances(springapplication.java:414) @ org.springframework.boot.springapplication.getspringfactoriesinstances(springapplication.java:394) @ org.springframework.bo...
Read more

reactjs - React router and this.props.children - how to pass state to this.props.children -

-
i'm using react-router first time , don't know how think in yet. here's how i'm loading components in nested routes. entry point .js reactdom.render( <router history={hashhistory} > <route path="/" component={app}> <route path="models" component={content}> </route> </router>, document.getelementbyid('app') ); app.js render: function() { return ( <div> <header /> {this.props.children} </div> ); } so child of app content component sent in. i'm using flux , app.js has state , listens changes, don't know how pass state down this.props.children. before using react-router app.js defines children explicitly, passing state natural don't see how now. using couple of react helper methods can add state, props , whatever else this.props.children render: function() { var children = react.ch...
Read more

Excel VBA "Microsoft Windows Common Controls 6.0 (SP6)" Location Changes -

-
i have excel workbook used generate quotations customers. there main page user inputs data, , there buttons generate various pdfs , send them customer. however, 1 user consistently getting error preventing generating , sending pdfs. i beleive "microsoft windows common controls 6.0 (sp6)". it's installed on users' computers. on mine, location "c:\windows\syswow64\mscomctl.ocx" on others "c:\windows\system32\mscomctl.ocx" the user experiencing issues on 32-bit machine, "mscomctl.ocx" file should in system32. have manually put in there, , pointed common controls reference in vba it. issue seems keep reverting looking in syswow64. since folder doesn't exist, can't find it, , can't produce pdfs. i thought perhaps issue user running older version of office (2007) there users on 2013 , 2016. thought perhaps mixture of 64-bit , 32-bit users. user gets sent workbook other users (as quotation process goes further, gets passed ...
Read more