java中字符串替换常用的4种方法

String str = "Hello World";
String newStr = str.replace("World", "Java");
System.out.println(newStr);  // 输出：Hello Java

String str = "Hello 123 World";
String newStr = str.replaceAll("[0-9]+", "");  // 移除所有数字
System.out.println(newStr);  // 输出：Hello  World

StringBuffer sb = new StringBuffer("Hello World");
sb.replace(6, 11, "Java");  // 将索引6到11的部分替换为"Java"
System.out.println(sb.toString());  // 输出：Hello Java

StringBuilder sb = new StringBuilder("Hello World");
sb.replace(6, 11, "Java");  // 将索引6到11的部分替换为"Java"
System.out.println(sb.toString());  // 输出：Hello Java

String str = "Hello 123 World";
Pattern pattern = Pattern.compile("[0-9]+");
Matcher matcher = pattern.matcher(str);
String newStr = matcher.replaceAll("");  // 移除所有数字
System.out.println(newStr);  // 输出：Hello  World

public class Demo1 {
public static void main(String[] args) {
StringBuffer buffer = new StringBuffer(“123456”);
System.out.println(buffer.toString());//输出123456
buffer.replace(0, 1, “a”);
System.out.println(buffer.toString());//输出a23456
}
}