### JAVA实验项目知识点详解
#### 项目一：Java 语言基础（一）
1. **编写控制台输出“Hello World!”的 Java 应用程序**
- **记事本编写**
```java
public class HelloWorld {
public static void main(String[] args) {
System.out.println("Hello World!");
}
}
```
- **Eclipse编写**
```java
public class HelloWorld {
public static void main(String[] args) {
System.out.println("Hello World!");
}
}
```
2. **程序输出分析**
- **示例程序**
```java
public class Exercise3_1 {
public static void main(String[] args) {
System.out.print("This is a ");
System.out.println("string. ");
}
}
```
- **输出结果**："This is a string. "
3. **绘制三角形图案**
- **示例程序**
```java
public class TrianglePattern {
public static void main(String[] args) {
for (int i = 1; i <= 5; i++) {
for (int j = 1; j <= i; j++) {
System.out.print("*");
}
System.out.println();
}
}
}
```
- **输出结果**
```
*
**
***
****
*****
```
4. **判断闰年**
- **示例程序**
```java
import java.util.Scanner;
public class LeapYear {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.print("请输入年份: ");
int year = scanner.nextInt();
if ((year % 4 == 0 && year % 100 != 0) || year % 400 == 0) {
System.out.println(year + " 是闰年");
} else {
System.out.println(year + " 不是闰年");
}
}
}
```
#### 项目二：Java 语言基础（二）
1. **测试典型运算符的使用**
- **示例程序**
```java
public class OperatorTest {
public static void main(String[] args) {
int a = 10;
int b = 20;
System.out.println("a + b = " + (a + b));
System.out.println("a - b = " + (a - b));
System.out.println("a * b = " + (a * b));
System.out.println("a / b = " + (a / b));
System.out.println("a % b = " + (a % b));
}
}
```
2. **斐波那契数列**
- **示例程序**
```java
public class Fibonacci {
public static void main(String[] args) {
int n = 10;
int t1 = 0, t2 = 1;
System.out.print("前 " + n + " 项: ");
for (int i = 1; i <= n; ++i) {
System.out.print(t1 + " ");
int sum = t1 + t2;
t1 = t2;
t2 = sum;
}
}
}
```
3. **水仙花数**
- **示例程序**
```java
public class NarcissisticNumber {
public static void main(String[] args) {
for (int i = 100; i < 1000; i++) {
int x = i / 100;
int y = i / 10 % 10;
int z = i % 10;
if (Math.pow(x, 3) + Math.pow(y, 3) + Math.pow(z, 3) == i) {
System.out.println(i);
}
}
}
}
```
#### 项目三：模块化程序设计
1. **计算数字的和及平均值**
- **示例程序**
```java
import java.util.Scanner;
public class SumAndAverage {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
int sum = 0;
int count = 0;
double average = 0.0;
while (true) {
System.out.print("请输入一个数字 (输入 0 结束): ");
int number = scanner.nextInt();
if (number == 0) {
break;
}
sum += number;
count++;
}
if (count > 0) {
average = (double) sum / count;
}
System.out.println("总和: " + sum);
System.out.println("平均值: " + average);
}
}
```
2. **购物折扣及赠券计算**
- **示例程序**
```java
import java.util.Scanner;
public class DiscountAndCoupon {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.print("请输入购物总额: ");
double totalAmount = scanner.nextDouble();
double discountAmount = 0;
double couponAmount = 0;
if (totalAmount >= 1000) {
discountAmount = totalAmount * 0.2;
couponAmount = 200;
} else if (totalAmount >= 500) {
discountAmount = totalAmount * 0.15;
couponAmount = 100;
} else if (totalAmount >= 300) {
discountAmount = totalAmount * 0.1;
couponAmount = 70;
} else {
discountAmount = totalAmount * 0.05;
}
System.out.println("折扣金额: " + discountAmount);
System.out.println("赠送购物券金额: " + couponAmount);
}
}
```
#### 项目四：数组的应用
1. **一维数组操作**
- **示例程序**
```java
import java.util.Arrays;
public class ArrayOperations {
public static void main(String[] args) {
int[] src1 = {1, 2, 3, 4, 5, 6};
int[] dest1 = Arrays.copyOf(src1, src1.length);
System.out.println(Arrays.toString(dest1));
}
}
```
2. **二维数组操作**
- **示例程序**
```java
public class MatrixOperations {
public static void main(String[] args) {
int[][] matrix = new int[6][6];
for (int i = 0; i < 6; i++) {
for (int j = 0; j < 6; j++) {
matrix[i][j] = (int) (Math.random() * 21 + 10);
}
}
// 打印矩阵
for (int i = 0; i < 6; i++) {
for (int j = 0; j < 6; j++) {
System.out.print(matrix[i][j] + " ");
}
System.out.println();
}
// 求最大元素值及其位置
int max = Integer.MIN_VALUE;
int[] maxPosition = new int[2];
for (int i = 0; i < 6; i++) {
for (int j = 0; j < 6; j++) {
if (matrix[i][j] > max) {
max = matrix[i][j];
maxPosition[0] = i;
maxPosition[1] = j;
}
}
}
System.out.println("最大值: " + max + " 位置: (" + maxPosition[0] + ", " + maxPosition[1] + ")");
// 转置矩阵
int[][] transposedMatrix = new int[6][6];
for (int i = 0; i < 6; i++) {
for (int j = 0; j < 6; j++) {
transposedMatrix[i][j] = matrix[j][i];
}
}
// 打印转置矩阵
System.out.println("转置矩阵:");
for (int i = 0; i < 6; i++) {
for (int j = 0; j < 6; j++) {
System.out.print(transposedMatrix[i][j] + " ");
}
System.out.println();
}
}
}
```
3. **冒泡排序**
- **示例程序**
```java
public class BubbleSort {
public static void main(String[] args) {
int[] arr = {4, 3, 9, 1, 6, 2, 8, 5, 7, 0};
for (int i = 0; i < arr.length - 1; i++) {
for (int j = 0; j < arr.length - 1 - i; j++) {
if (arr[j] > arr[j + 1]) {
int temp = arr[j];
arr[j] = arr[j + 1];
arr[j + 1] = temp;
}
}
}
System.out.println(Arrays.toString(arr));
}
}
```
#### 项目五：类和对象
1. **程序改错**
- **第一个程序**
```java
public class Test1 {
private String data1 = "中国，我爱你！";
public static void main(String[] args) {
System.out.println(data1); // 修改：添加static关键字
}
}
```
- **第二个程序**
```java
public class Test1 {
public void showData() {
System.out.println("中国，我爱你！");
}
public static void main(String[] args) {
Test1 test1 = new Test1(); // 修改：实例化对象并调用方法
test1.showData();
}
}
```
2. **定义学生类**
- **示例程序**
```java
public class Student {
private long studentID;
private int classID;
private String name;
private String sex;
private int age;
// Getter and Setter methods
public long getStudentID() {
return studentID;
}
public void setStudentID(long studentID) {
this.studentID = studentID;
}
public int getClassID() {
return classID;
}
public void setClassID(int classID) {
this.classID = classID;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getSex() {
return sex;
}
public void setSex(String sex) {
this.sex = sex;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
// Constructor
public Student(long studentID, int classID, String name, String sex, int age) {
this.studentID = studentID;
this.classID = classID;
this.name = name;
this.sex = sex;
this.age = age;
}
// toString method
@Override
public String toString() {
return "Student{" +
"studentID=" + studentID +
", classID=" + classID +
", name='" + name + '\'' +
", sex='" + sex + '\'' +
", age=" + age +
'}';
}
// Main method to create objects and print information
public static void main(String[] args) {
Student student1 = new Student(123456, 1, "张三", "男", 20);
System.out.println(student1);
}
}
```
以上是针对给定文件中的各个任务进行的详细解析和示例代码展示，希望能够帮助理解和掌握相关的Java基础知识和技术要点。
