列举十个常用的经典java优秀代码案例
时间: 2023-11-26 07:03:52 浏览: 31
好的,以下是十个常用的经典Java优秀代码案例:
1. 简单的Hello World程序:
```java
public class HelloWorld {
public static void main(String[] args) {
System.out.println("Hello, World!");
}
}
```
2. 递归实现斐波那契数列:
```java
public class Fibonacci {
public static int fibonacci(int num) {
if (num <= 1) return num;
return fibonacci(num - 1) + fibonacci(num - 2);
}
}
```
3. 遍历数组并输出:
```java
public class ArrayTraversal {
public static void main(String[] args) {
int[] arr = {1, 2, 3, 4, 5};
for (int i = 0; i < arr.length; i++) {
System.out.print(arr[i] + " ");
}
}
}
```
4. 计算圆的面积:
```java
public class CircleArea {
public static void main(String[] args) {
final double PI = 3.1415926;
double radius = 5.0;
double area = PI * radius * radius;
System.out.println("The area of the circle is " + area);
}
}
```
5. 使用Scanner类读取用户输入:
```java
import java.util.Scanner;
public class UserInput {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.print("Please enter your name: ");
String name = scanner.nextLine();
System.out.println("Hello, " + name + "!");
}
}
```
6. 使用try-catch语句处理异常:
```java
public class ExceptionHandling {
public static void main(String[] args) {
int[] arr = {1, 2, 3};
try {
System.out.println(arr[3]);
} catch (Exception e) {
System.out.println("An error occurred: " + e.getMessage());
}
}
}
```
7. 使用HashMap类存储数据:
```java
import java.util.HashMap;
public class HashMapExample {
public static void main(String[] args) {
HashMap<String, Integer> map = new HashMap<String, Integer>();
map.put("John", 25);
map.put("Jane", 30);
System.out.println("John is " + map.get("John") + " years old.");
}
}
```
8. 使用ArrayList类存储数据:
```java
import java.util.ArrayList;
public class ArrayListExample {
public static void main(String[] args) {
ArrayList<String> list = new ArrayList<String>();
list.add("apple");
list.add("banana");
list.add("orange");
System.out.println("The second item in the list is " + list.get(1));
}
}
```
9. 使用StringBuilder类构建字符串:
```java
public class StringBuilderExample {
public static void main(String[] args) {
StringBuilder sb = new StringBuilder();
sb.append("Hello");
sb.append(" ");
sb.append("World");
sb.append("!");
String result = sb.toString();
System.out.println(result);
}
}
```
10. 使用正则表达式匹配字符串:
```java
public class RegexExample {
public static void main(String[] args) {
String input = "The quick brown fox jumps over the lazy dog.";
String pattern = "fox";
boolean match = input.matches(".*" + pattern + ".*");
System.out.println("The string contains 'fox': " + match);
}
}
```