java实验考.doc

1.(25分)产生一个int数组a，长度为100，并向其中随机填充三位的整数，然后再从该100个随机数中任意抽取10形成一个10个数的数组b，再将数组b输出。
代码：
/**
* 1.(25分)产生一个int数组a，长度为100，并向其中随机填充三位的整数，
* 然后再从该100个随机数中任意抽取10形成一个10个数的数组b，再将数组b输出。
* @version 1.0
*/
package wangshuai;//数组a，100
import java.util.Random;
public class RandomArray {
public static int[] getArray(int length, int downLimit, int upLinit) {
int[] originalArr = new int[length];
int[] result = new int[10];
Random r = new Random();
for (int i = 0; i < originalArr.length; i++) {
originalArr[i] = r.nextInt(upLinit - downLimit + 1) + downLimit;
}
int point = originalArr.length;
for (int i = 0; i < 10; i++) {
int temp = r.nextInt(point);
result[i] = originalArr[temp];
originalArr[temp] = originalArr[point - 1];
point--;
}
return result;
}
public static void main(String[] args) {
int[] result = getArray(100, 100, 999);
System.out.print("结果数组：");
for (int i : result) {
System.out.print(i + " ");
}
}
}
2. (25分)请产生一个6字符的随机字符串，要求
(1)必须包含数字和字母(a-z或者A-Z);
（2）不能以数字开头
(3)字母和数字的个数随机(即为5字母+1数字或者4字母+2数字，...)；
再对该字符串按照字母顺序进行排序。

package wangshuai;
import java.util.Random;
public class RandomString {
public char[] dict;
//随机产生6字符的随机字符串
public RandomString(char[] initDict) {
dict = new char[initDict.length];
for (int i = 0; i < initDict.length; i++) {
this.dict[i] = initDict[i];
}
}
public String getRandomString(int length) {
int len = dict.length;
Random r = new Random();
char[] result = new char[length];
do {
for (int i = 0; i < length; i++) {
result[i] = dict[r.nextInt(len)];
}
} while (!checkString(result));
System.out.println(new String(result));
sort(result);
return new String(result);
}
public static boolean checkString(char[] arr) {
if (arr == null) {
return false;
}
if (arr[0] >= '0' && arr[0] <= '9') {
return false;
}
for (int i = 1; i < arr.length; i++) {
if (arr[i] >= '0' && arr[i] <= '9') {
return true;
}
}
return false;
}
//对随机产生的字符串进行排序
public void sort(char[] result) {
int len = result.length;
for (int i = 0; i < len; i++) {
for (int j = 0; j < len; j++) {
if (result[i] >= '0' && result[i] <= '9') {
continue;
}
if (result[j] >= '0' && result[j] <= '9') {
continue;
}
if (result[i] < result[j]) {
char temp = result[i];//采用中间变量进行调换
result[i] = result[j];
result[j] = temp;
}
}
}//两个for循环通过比较ASCII实现排序
}
public static void main(String[] args) {
char[] dict = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a','b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm','n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y','z', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K','L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W','X', 'Y', 'Z' };
RandomString rs = new RandomString(dict);
String result = rs.getRandomString(6);
System.out.print(result);
}
}
二、 面向对象题
1. 定义接口AreaInterface,该接口有一个双精度浮点型的变量PI，它的值等于Math.PI；含有一个求面积的方法 double area()；再定义一个类Rectangle，实现接口AreaInterface，包含成员左上角点、宽和高，并且定义一个新的方法double length()，该方法返回矩形的周长；定义接口MoveAble，包含方法void move(int delx,int dely)；再定义类Circle，要求该类实现AreaInterface和MoveAble接口，包含了成员圆心和半径。请编写主程序,在主程序中，需要完成：
(1) 定义一个左上角在（10,10）的矩形，宽度为600，高度为480的矩形对象，然后输出该矩形对象的面积以及周长；
(2) 定义5个圆对象，每个圆的圆心是(0.0)-(100,100)矩形区域中的一个随机点，半径为100-200之间的随机整数，这5个圆用一个ArrayList存放，请输出他们的面积并将他们随机的沿着x方向移动20-50距离，沿着y方向移动同样范围的随机距离；然后再将这存放这5个圆的ArrayList采用DataOutputStream保存到文件circles.dat中。
源代码：
//定义接口AreaInterface,含有一个求面积的方法 double area()
public interface AreaInterface {
public final double PI = Math.PI;
public double area();
}
//定义接口MoveAble，包含方法void move(int delx,int dely)
public interface MoveAble {
void move(int delx, int dely);
}
//定义类Rectangle，实现接口AreaInterface，包含成员左上角点、宽和高，并且定义一个新的方法double length()，该方法返回矩形的周长
public class Rectangle implements AreaInterface {
private int leftTopX;
private int leftTopY;
private double high;
private double width;
public Rectangle() {
super();
}

public Rectangle(int leftTopX, int leftTopY) {
super();
this.leftTopX = leftTopX;
this.leftTopY = leftTopY;
}
public Rectangle(int leftTopX, int leftTopY, double hight, double width) {
super();
this.leftTopX = leftTopX;
this.leftTopY = leftTopY;
this.high = hight;
this.width = width;
}
public int getLeftTopX() {
return leftTopX;
}
public void setLeftTopX(int leftTopX) {
this.leftTopX = leftTopX;
}
public int getLeftTopY() {
return leftTopY;
}
public void setLeftTopY(int leftTopY) {
this.leftTopY = leftTopY;
}
public double getHight() {
return high;
}
public void setHight(double hight) {
this.high = hight;
}
public double getWidth() {
return width;
}
public void setWidth(double width) {
this.width = width;
}
@Override
public double area() {
// TODO Auto-generated method stub
return high * width;
}
public double length() {
return 2 * (high + width);
}
}
//定义类Circle，实现AreaInterface和MoveAble接口，包含了成员圆心和半径
public class Circle implements AreaInterface, MoveAble {
private int centerX;
private int centerY;
private double radius;
public Circle() {
super();
}
public Circle(int centerX, int centerY, double radius) {
this.centerX = centerX;
this.centerY = centerY;
this.radius = radius;
}
public int getCenterX() {
return centerX;
}
public void setCenterX(int centerX) {
this.centerX = centerX;
}
public int getCenterY() {
return centerY;
}
public void setCenterY(int centerY) {
this.centerY = centerY;
}
public double getRadius() {
return radius;
}
public void setRadius(double radius) {
this.radius = radius;
}
@Override
public double area() {
return PI * Math.pow(radius, 2);
}
@Override
public void move(int delx, int dely) {
this.centerX += delx;
this.centerY += dely;
}
}
//定义类ExamTest01
public class ExamTest01 {
public ExamTest01() {
Rectangle rec = new Rectangle(10, 10, 800, 600);
System.out.println("矩形的面积为：" + rec.area());
System.out.println("矩形的周长为：" + rec.length());
}

public static void main(String[] args) {
// TODO Auto-generated method stub
new ExamTest01();
}
}
//定义类ExamTest02
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Random;
public class ExamTest02 {
public ExamTest02() throws IOException {
List<Circle> list = new ArrayList<>();
Circle circle = null;
Random r = new Random();
for (int i = 0; i < 5; i++) {
int centerX = r.nextInt(101);
int centerY = r.nextInt(101);
double radius = r.nextDouble() * 100 + 100;
circle = new Circle(centerX, centerY, radius);
int delX = r.nextInt(31) + 20;
int delY = r.nextInt(31) + 20;
circle.move(delX, delY);
System.out.println("第" + (i+1) + "个圆的面积为：" + circle.area());
list.add(circle);
}
saveResult("circles.dat", list);

}
public void saveResult(String src,List<Circle> result) throws IOException{
Iterator<Circle> iter = null;
Circle circle = null;
File file = new File(src);
if(!file.exists()){
file.createNewFile();
}
FileOutputStream fos = new FileOutputStream(file);
DataOutputStream dos = new DataOutputStream(fos);
iter = result.iterator();
while(iter.hasNext()){
circle = iter.next();
dos.writeInt(circle.getCenterX());
dos.writeInt(circle.getCenterY());
dos.writeDouble(circle.getRadius());
dos.writeDouble(circle.area());
}
dos.close();
fos.close();
}

public static void main(String[] args) throws IOException {
// TODO Auto-generated method stub
new ExamTest02();
}
}