string在java中的用法

// string在Java中的用法

// 1. 创建字符串
String str1 = "Hello, World!";
String str2 = new String("Hello, Java!");

// 2. 字符串连接
String str3 = str1 + " " + str2;
System.out.println(str3); // 输出: Hello, World! Hello, Java!

// 3. 获取字符串长度
int length = str1.length();
System.out.println("Length of str1: " + length); // 输出: Length of str1: 13

// 4. 字符串比较
boolean isEqual = str1.equals(str2);
System.out.println("Are str1 and str2 equal? " + isEqual); // 输出: Are str1 and str2 equal? false

// 5. 忽略大小写比较
boolean isEqualIgnoreCase = str1.equalsIgnoreCase("hello, world!");
System.out.println("Are str1 and 'hello, world!' equal ignoring case? " + isEqualIgnoreCase); // 输出: Are str1 and 'hello, world!' equal ignoring case? true

// 6. 查找子字符串
int index = str1.indexOf("World");
System.out.println("Index of 'World' in str1: " + index); // 输出: Index of 'World' in str1: 7

// 7. 替换子字符串
String replacedStr = str1.replace("World", "Universe");
System.out.println("Replaced string: " + replacedStr); // 输出: Replaced string: Hello, Universe!

// 8. 转换为大写或小写
String upperCaseStr = str1.toUpperCase();
String lowerCaseStr = str1.toLowerCase();
System.out.println("Uppercase: " + upperCaseStr); // 输出: Uppercase: HELLO, WORLD!
System.out.println("Lowercase: " + lowerCaseStr); // 输出: Lowercase: hello, world!

// 9. 去除前后空格
String strWithSpaces = "   Hello, Java!   ";
String trimmedStr = strWithSpaces.trim();
System.out.println("Trimmed string: '" + trimmedStr + "'"); // 输出: Trimmed string: 'Hello, Java!'