1. 在IDE中輸入並觀察以下代碼，分析該段程序的作用。
public abstract class GeometricObject {
private String color = "white";
private boolean filled;
private java.util.Date dateCreated;
protected GeometricObject(){
dateCreated = new java.util.Date();
}
protected GeometricObject(String colr, boolean filled){
dateCreated = new java.util.Date();
this.color = color;
this.filled = filled;
}
public String getColor(){
return color;
}
public void setColor(String color){
this.color = color;
}
public boolean isFilled(){
return filled;
}
public void setFilled(boolean filled){
this.filled = filled;
}
public java.util.Date getDateCreated(){
return dateCreated;
}
public String toString(){
return "created on " + dateCreated + "\ncolor: " + color + " and filled: " + filled;
}
public abstract double getArea();
public abstract double getPerimeter();
}
2. 編寫程序。
使用Java API中提供的Comparable接口，設計和實現名爲ComparableMatrix的類，使ComparableMatrix類的對象之間存在可比性，比較規則如下：
(1) 給定參與比較的矩陣（兩個對象分別標識爲A和B），如果矩陣行列數不相同，則比較兩個矩陣所包含的元素個數，元素個數較多的矩陣（如果爲A）通過比較被認定爲“Larger coverage”，即A.compareTo(B)返回1；同理，在個數相同的情況下返回0（Equal coverage），否則返回-1（Smaller coverage）；
(2) 如果矩陣行列數相同，則依次比較對應位置上的元素值，當一個矩陣（如果爲A）中所含的較大元素個數超過矩陣元素總數的一半，則認定該矩陣爲“Larger grid”，即A.compareTo(B)返回1；如果參與比較的矩陣各對應位置上元素均相同，則認定“Equal grid”，返回0；此外，認定爲“Less grid”，返回-1。
3. 編寫程序。
設計一個名爲Colorable接口，其中有名爲howToColor()的void方法。可着色對象的每個類必須實現Colorable接口。設計一個擴展GeometricObject類並實現Colorable接口的名爲Square，Circle，Triangle的類，實現howToColor方法。例如針對Square，顯示消息“Color all four sides”，對於其他的着色方法，請自行設計。
1、
package org.cust.test5;
public abstract class GeometricObject {
private String color = "white";
private boolean filled;
private java.util.Date dateCreated;
protected GeometricObject() {
dateCreated = new java.util.Date();
}
protected GeometricObject(String colr, boolean filled) {
dateCreated = new java.util.Date();
this.color = color;
this.filled = filled;
}
public String getColor() {
return color;
}
public void setColor(String color) {
this.color = color;
}
public boolean isFilled() {
return filled;
}
public void setFilled(boolean filled) {
this.filled = filled;
}
public java.util.Date getDateCreated() {
return dateCreated;
}
public String toString() {
return "created on " + dateCreated + "\ncolor: " + color + " and filled: " + filled;
}
public abstract double getArea();
public abstract double getPerimeter();
}
/**
* 這是一個抽象類帶有String屬性color、boolean型屬性filled、
* （util）Date型屬性dateCreated
* 兩個構造方法
* 以及獲得各種屬性的方法
* 以及自帶toString方法輸出所有屬性
* 以及兩個抽象方法 需要子類繼承重寫該方法才能使用
*/
2、
package org.cust.test5;
import java.util.InputMismatchException;
import java.util.Scanner;
public class ComparableMatrix implements Comparable<ComparableMatrix> {
private int x;
private int y;
private int[][] matrix;
public ComparableMatrix(int x, int y) {
this.x = x;
this.y = y;
this.matrix = new int[this.x][this.y];
this.matrix = this.matrixEnter(this.x, this.y);
}
public int[][] matrixEnter(int x, int y) {
int[][] matrix = new int[x][y];
Scanner in = new Scanner(System.in);
System.out.println("對象矩陣初始化輸入：\n");
for (int i = 0; i < x; i++) {
for (int j = 0; j < y; j++) {
try {
matrix[i][j] = in.nextInt();
} catch (InputMismatchException e) {
// TODO Auto-generated catch block
in = new Scanner(System.in);
System.out.println("請輸入整形數字");
j--;
continue;
}
}
}
System.out.println("矩陣輸入完成");
// for (int i = 0; i < this.matrix.length; i++) {
// System.out.println("矩陣的長度："+this.matrix.length);
// for (int j = 0; j < this.matrix[0].length; j++) {
// System.out.println(this.matrix[i][j]);
// }
// }
return matrix;
}
@Override
public int compareTo(ComparableMatrix cm) {
// TODO Auto-generated method stub
if (this.x != cm.x || this.y != cm.y) {
if (this.x * this.y > cm.x * cm.y) {
return 1;
} else if (this.x * this.y < cm.x * cm.y) {
return -1;
} else {
return 0;
}
} else {
int sum = this.x * this.y, overCount = 0, equalCount = 0;
for (int i = 0; i < this.matrix.length; i++) {
for (int j = 0; j < this.matrix[0].length; j++) {
if (this.matrix[i][j] > cm.matrix[i][j]) {
overCount++;
} else if (this.matrix[i][j] == cm.matrix[i][j]) {
equalCount++;
// System.out.println("++");
} else {
}
// System.out.println(this.matrix[i][j]);
// System.out.println(cm.matrix[i][j]);
}
}
// System.out.println("overCount:" + overCount);
// System.out.println("sum/2:" + sum / 2);
// System.out.println("sum:" + sum);
// System.out.println("equalCount:" + equalCount);
if (overCount > sum / 2) {
return 1;
} else if (equalCount == sum) {
return 0;
} else {
return -1;
}
}
}
public static void main(String[] args) {
ComparableMatrix a = new ComparableMatrix(2, 2);
ComparableMatrix b = new ComparableMatrix(2, 2);
System.out.println("The result of 'a copareTO a':" + a.compareTo(a));
System.out.println("The result of 'a copareTO b':" + a.compareTo(b));
}
}
3、
package org.cust.test5;
public class Circle extends GeometricObject implements Colorable {
@Override
public void howToColor() {
// TODO Auto-generated method stub
System.out.println("Color inside");
}
@Override
public double getArea() {
// TODO Auto-generated method stub
return 0;
}
@Override
public double getPerimeter() {
// TODO Auto-generated method stub
return 0;
}
}
package org.cust.test5;
public class Square extends GeometricObject implements Colorable {
@Override
public void howToColor() {
// TODO Auto-generated method stub
System.out.println("Color all four sides");
}
@Override
public double getArea() {
// TODO Auto-generated method stub
return 0;
}
@Override
public double getPerimeter() {
// TODO Auto-generated method stub
return 0;
}
}
package org.cust.test5;
public class Triangle extends GeometricObject implements Colorable {
@Override
public void howToColor() {
// TODO Auto-generated method stub
System.out.println("Color all three sides");
}
@Override
public double getArea() {
// TODO Auto-generated method stub
return 0;
}
@Override
public double getPerimeter() {
// TODO Auto-generated method stub
return 0;
}
}
package org.cust.test5;
public interface Colorable {
void howToColor();
}
package org.cust.test5;
public class Test {
public static void main(String[] args) {
Square s = new Square();
Circle c = new Circle();
Triangle t = new Triangle();
s.howToColor();
c.howToColor();
t.howToColor();
}
}