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--- zh:courses:java2026:ch04 [2026/03/30 18:50]
pzczxs 创建
+++ zh:courses:java2026:ch04 [2026/04/06 20:08] (当前版本)
pzczxs [上机作业]
@@ 行 1: / 行 1: @@
 ====== 第四章：封装、继承与多态 ======
 ===== 课件 =====
-下载：封装、继承与多态
+下载：{{ :zh:courses:java2026:ch04.pptx |封装、继承与多态}}
 ===== 面向对象的三大特性：封装 =====
@@ 行 654: / 行 654: @@
 ===== 上机作业 =====
   *专利文档中不仅有IPC分类号，还有CPC分类号，CPC的格式与IPC类似，但多了两个字段position和value，这两个字段取值为单个字符，请重写Ipc类和Cpc类，并增加一个父类Classification；
+【参考答案】
+<file java Classification.java>
+package cn.edu.bjut.chapter4;
+public class Classification {
+	protected char section;
+	protected int mainClass;
+	protected char subclass;
+	protected int mainGroup;
+	protected int subgroup;
+	public final static char SEPARATOR = '/';
+	public Classification(char section, int mainClass, char subclass, int mainGroup, int subgroup) {
+		this.section = section;
+		this.mainClass = mainClass;
+		this.subclass = subclass;
+		this.mainGroup = mainGroup;
+		this.subgroup = subgroup;
+	}
+	// example: G09F 17/30
+	public Classification(String symbol) {
+		this.section = symbol.charAt(0);
+		this.mainClass = Integer.parseInt(symbol.substring(1, 3));
+		this.subclass = symbol.charAt(3);
+		int pos = symbol.indexOf(SEPARATOR);
+		this.mainGroup = Integer.parseInt(symbol.substring(4, pos).trim());
+		this.subgroup = Integer.parseInt(symbol.substring(pos + 1));
+	}
+	public char getSection() {
+		return section;
+	}
+	public void setSection(char section) {
+		this.section = section;
+	}
+	public int getMainClass() {
+		return mainClass;
+	}
+	public void setMainClass(int mainClass) {
+		this.mainClass = mainClass;
+	}
+	public char getSubclass() {
+		return subclass;
+	}
+	public void setSubclass(char subclass) {
+		this.subclass = subclass;
+	}
+	public int getMainGroup() {
+		return mainGroup;
+	}
+	public void setMainGroup(int mainGroup) {
+		this.mainGroup = mainGroup;
+	}
+	public int getSubgroup() {
+		return subgroup;
+	}
+	public void setSubgroup(int subgroup) {
+		this.subgroup = subgroup;
+	}
+	@Override
+	public String toString() {
+		StringBuilder sb = new StringBuilder();
+		sb.append(section);
+		String strMainClass = String.format("%2s", mainClass).replace(' ', '0');
+		sb.append(strMainClass);
+		sb.append(subclass);
+		String strMainGroup = String.format("%4s", mainGroup);
+		sb.append(strMainGroup);
+		sb.append(SEPARATOR);
+		sb.append(subgroup);
+		return sb.toString();
+	}
+}
+</file>
+<file java Ipc.java>
+package cn.edu.bjut.chapter4;
+public class Ipc extends Classification {
+	public Ipc(char section, int mainClass, char subclass, int mainGroup, int subgroup) {
+		super(section, mainClass, subclass, mainGroup, subgroup);
+	}
+	public Ipc(String symbol) {
+		super(symbol);
+	}
+	public static void main(String[] args) {
+		char section = 'A';
+		int mainClass = 4;
+		char subclass = 'B';
+		int mainGroup = 55;
+		int subgroup = 56;
+		Classification ipc = new Ipc(section, mainClass, subclass, mainGroup, subgroup);
+		System.out.println(ipc);
+		String symbol = "G09F 17/30";
+		System.out.println(new Ipc(symbol));
+	}
+}
+</file>
+<file java Cpc.java>
+package cn.edu.bjut.chapter4;
+public class Cpc extends Classification {
+	private char position;
+	private char value;
+	public Cpc(char section, int mainClass, char subclass, int mainGroup, int subgroup, char position, char value) {
+		super(section, mainClass, subclass, mainGroup, subgroup);
+		this.position = position;
+		this.value = value;
+	}
+	public Cpc(String symbol, char position, char value) {
+		super(symbol);
+		this.position = position;
+		this.value = value;
+	}
+	public char getPosition() {
+		return position;
+	}
+	public void setPosition(char position) {
+		this.position = position;
+	}
+	public char getValue() {
+		return value;
+	}
+	public void setValue(char value) {
+		this.value = value;
+	}
+}
+</file>
   *仔细观察身边的事物，对其进行抽象化处理，但需包括父类和父接口等。
 [[zh:courses:java2026:index|返回Java课程页]]
-~~DISCUSSION:closed~~
+~~DISCUSSION~~

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