黑龙江省城乡和住房建设厅网站首页简述seo和sem的区别与联系

黑龙江省城乡和住房建设厅网站首页,简述seo和sem的区别与联系,wordpress建站图片效果,网上商店是指https://www.jb51.net/program/330116r71.htm 问题场景 子类StudentResp继承父类PersonResp#xff0c;子类也拥有了父类的属性。 给子类中继承的父类属性的赋值#xff0c;但是打印了以后只会显示子类信息#xff0c;父类信息不显示。 子类#xff1a;学生类继承父类人…https://www.jb51.net/program/330116r71.htm问题场景子类StudentResp继承父类PersonResp子类也拥有了父类的属性。给子类中继承的父类属性的赋值但是打印了以后只会显示子类信息父类信息不显示。子类学生类继承父类人员类12345678910111213DatapublicclassStudentRespextendsPersonResp {/*** 学号*/privateInteger studentId;/*** 成绩*/privateInteger score;}父类人员类12345678910111213DatapublicclassPersonResp {/*** 姓名*/privateString name;/*** 年龄*/privateInteger age;}代码中给子类以及继承的父类信息赋值然后打印12345678910111213publicstaticvoidmain (String[] args) {StudentResp studentResp newStudentResp();//学生子类赋值studentResp.setStudentId(1000000000);studentResp.setScore(92);//父类赋值studentResp.setName(风清扬);studentResp.setAge(18);//打印学生子类信息System.out.println(studentResp);}打印出来只有子类自己的属性父类的属性没有出来问题分析单独获取子类中父类的信息name跟age观察打印看有没有值1234567891011121314publicstaticvoidmain (String[] args) {StudentResp studentResp newStudentResp();//学生子类赋值studentResp.setStudentId(1000000000);studentResp.setScore(92);//父类赋值studentResp.setName(风清扬);studentResp.setAge(18);//打印父类信息System.out.println(姓名 studentResp.getName());System.out.println(年龄 studentResp.getAge());}打印出来发现是有值的确认了继承本身是没有问题的继承的父类的值都可以给上也能获取到随后直接打开target对应目录下的StudentResp子类观察编译后的代码12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152535455565758596061626364656667686970717273747576publicclassStudentRespextendsPersonResp {privateInteger studentId;privateInteger score;publicStudentResp() {}publicInteger getStudentId() {returnthis.studentId;}publicInteger getScore() {returnthis.score;}publicvoidsetStudentId(finalInteger studentId) {this.studentId studentId;}publicvoidsetScore(finalInteger score) {this.score score;}publicbooleanequals(finalObject o) {if(o this) {returntrue;}elseif(!(oinstanceofStudentResp)) {returnfalse;}else{StudentResp other (StudentResp)o;if(!other.canEqual(this)) {returnfalse;}else{Objectthis$studentId this.getStudentId();Object other$studentId other.getStudentId();if(this$studentId null) {if(other$studentId !null) {returnfalse;}}elseif(!this$studentId.equals(other$studentId)) {returnfalse;}Objectthis$score this.getScore();Object other$score other.getScore();if(this$score null) {if(other$score !null) {returnfalse;}}elseif(!this$score.equals(other$score)) {returnfalse;}returntrue;}}}protectedbooleancanEqual(finalObject other) {returnotherinstanceofStudentResp;}publicinthashCode() {intPRIME true;intresult 1;Object $studentId this.getStudentId();intresult result *59 ($studentId null?43: $studentId.hashCode());Object $score this.getScore();result result *59 ($score null?43: $score.hashCode());returnresult;}publicString toString() {returnStudentResp(studentIdthis.getStudentId() , scorethis.getScore() );}}看到这里大多数同学应该已经定位到出现问题的原因了。最后的toString()方法可以明确的看到这里只取了子类本身的两个属性并没有去获取父类的属性。问题原因通过看编译后的代码可以得出Data不会打印继承的父类信息是因为该注解本身作用域的问题Data注解在编译时会自动给实体类添加SetterGetterToString等方法。但是Data注解的作用域只在当前类中所以最终打印的时候只会打印出当前类子类的信息。即使子类拥有的是全属性但是打印不会显示父类信息。解决方式本文介绍两种解决方案。第一种在子类上添加ToString(callSuper true)注解该注解会将父类的属性跟子类的属性一起生成toString第二种不使用Data注解使用SetterGetter注解在父类中重写toString()方法并用JSON的方式打印。1.子类添加ToString(callSuper true)注解1234567891011121314DataToString(callSuper true)publicclassStudentRespextendsPersonResp {/*** 学号*/privateInteger studentId;/*** 成绩*/privateInteger score;}打印子类12345678910111213publicstaticvoidmain (String[] args) {StudentResp studentResp newStudentResp();//学生子类赋值studentResp.setStudentId(1000000000);studentResp.setScore(92);//父类赋值studentResp.setName(风清扬);studentResp.setAge(18);//学生子类System.out.println(studentResp);}结果可以看到父类信息再看看target中子类编译后的代码12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152535455565758596061626364656667686970717273747576publicclassStudentRespextendsPersonResp {privateInteger studentId;privateInteger score;publicStudentResp() {}publicInteger getStudentId() {returnthis.studentId;}publicInteger getScore() {returnthis.score;}publicvoidsetStudentId(finalInteger studentId) {this.studentId studentId;}publicvoidsetScore(finalInteger score) {this.score score;}publicbooleanequals(finalObject o) {if(o this) {returntrue;}elseif(!(oinstanceofStudentResp)) {returnfalse;}else{StudentResp other (StudentResp)o;if(!other.canEqual(this)) {returnfalse;}else{Objectthis$studentId this.getStudentId();Object other$studentId other.getStudentId();if(this$studentId null) {if(other$studentId !null) {returnfalse;}}elseif(!this$studentId.equals(other$studentId)) {returnfalse;}Objectthis$score this.getScore();Object other$score other.getScore();if(this$score null) {if(other$score !null) {returnfalse;}}elseif(!this$score.equals(other$score)) {returnfalse;}returntrue;}}}protectedbooleancanEqual(finalObject other) {returnotherinstanceofStudentResp;}publicinthashCode() {intPRIME true;intresult 1;Object $studentId this.getStudentId();intresult result *59 ($studentId null?43: $studentId.hashCode());Object $score this.getScore();result result *59 ($score null?43: $score.hashCode());returnresult;}publicString toString() {returnStudentResp(supersuper.toString() , studentIdthis.getStudentId() , scorethis.getScore() );}}可以明确的看到最后的toString()方法中多了一个super.toString()方法将父类的信息打印出来2.不使用Data注解使用SetterGetter注解在父类中重写toString()方法并用JSON的方式打印。子类使用SetterGetter注解1234567891011121314GetterSetterpublicclassStudentRespextendsPersonResp {/*** 学号*/privateInteger studentId;/*** 成绩*/privateInteger score;}父类中重写toString()方法并用JSON的方式打印1234567891011121314151617181920DatapublicclassPersonResp {/*** 姓名*/privateString name;/*** 年龄*/privateInteger age;OverridepublicString toString() {returnJSON.toJSONString(this);}}打印子类12345678910111213publicstaticvoidmain (String[] args) {StudentResp studentResp newStudentResp();//学生子类赋值studentResp.setStudentId(1000000000);studentResp.setScore(92);//父类赋值studentResp.setName(风清扬);studentResp.setAge(18);//学生子类System.out.println(studentResp);}结果也可以看到父类信息总结这个问题本身不算是个大问题延伸出来更为重要的是我们解决问题的思路。因为从本质上来说属性本身都是存在的只是没打印出来。但是遇到这个问题的时候第一反应都是明明继承了父类为啥父类的值会没有从而会带偏我们去解决问题方向遇到此类问题第一我们应该先确认问题的本质到底有没有给上值确认了已经给上值就说明只是打印的问题进而去编译后的代码中查看为啥没打印出来最终定位到问题从而解决问题。