java 字符串操作

以下是Java中常见的字符串操作示例：

1. 字符串拼接

String str1 = "Hello";
String str2 = "World";
String result = str1 + " " + str2; // 输出：Hello World

2. 字符串长度

String str = "Hello";
int length = str.length(); // 输出：5

3. 字符串查找

String str = "Hello World";
int index = str.indexOf("World"); // 输出：6

4. 字符串替换

String str = "This is a String";
String newStr = str.replace("is", "was"); // 输出：Thwas was a String

5. 字符串分割

String str = "Hello,World";
String[] parts = str.split(","); // parts = ["Hello", "World"]

6. 字符串转换为大写或小写

String str = "Hello";
String upperCase = str.toUpperCase(); // 输出：HELLO
String lowerCase = str.toLowerCase(); // 输出：hello

7. 字符串去除首尾空格

String str = "  Hello  ";
String trimmedStr = str.trim(); // 输出：Hello