abstract class A{ private String name; public A(String name) { this.name = name; } public String getName() { return this.name; } public abstract void fun(); } class B extends A{ public B(String name) { super(name); } public void fun() { System.out.println(super.getName()); } } public class L { public static void main(String[] args) { // TODO Auto-generated method stub B b = new B(null); b.fun(); } } import java.sql.Date; @SuppressWarnings("unused") public abstract class Y { private String name; private String Class; private String date; public String getName() { return this.name; } public void setName(String name) { this.name = name; } public String GetClass() { return this.Class; } public void setClass(String Class) { this.Class = Class; } public String getDate() { return this.date; } public void setDate(String date) { this.date = date; } public Y(String name,String Class,String date) { this.name = name; this.Class = Class; this.date = date; } public Y() { super(); } @Override public String toString() { return "Student [name=" + name + "]"; } public abstract String speak(); } import java.sql.Date; @SuppressWarnings("unused") public class H extends Y{ private String matter; public H(String name,String Class,String date,String matter) { super(name,Class,date); this.setMatter(matter); } @Override public String speak() { return "我叫 " + super.getName() + " 今年 " + super.GetClass() + " 身高 " + super.getDate() + " 体重 " + this.matter; } public String getMatter() { return matter; } public void setMatter(String matter) { this.matter = matter; } } public class K { public static void main(String[] args) { // TODO Auto-generated method stub Y stu = new H("cty,","21岁了,","175cm,",62KG。"); print(stu.speak()); } private static void print(String speak) { System.out.println(speak); } }