java 需要对一个字符串重复赋值，能优化吗？

java 需要对一个字符串重复赋值，能优化吗？
示例代码：
String str = "abc";
str = findAndReplace("a","b",str);
str = findAndReplace("c","d",str);
str = findAndReplace("e","f",str);
......
需要多次调用方法，返回替换后的String,赋值给原String str，再用str作为下一次调用的入参
求教 这种情况怎么才是最优的写法？

str = findAndReplace("a","b",str). findAndReplace("c","d",str). findAndReplace("e","f",str);

是想要这样的效果吗

public class Main {
    public static void main(String[] args) {
        String str = "abc";
        str = str.replace("a", "b").replace("c", "d").replace("e", "f");
        System.out.println(str);
    }
}

String str = "abc";
str.replace("a","b").replace("c","d").replace("e","f");

我认为最佳的解决办法：将str定义为静态变量，findAndReplace()方法中直接对静态变量进行操作
public static String str = "abc";
findAndReplace("a","b");
findAndReplace("c","d");
findAndReplace("e","f");
...