java 去掉或轮换字符串中指定字符或空格或 等

java 去掉或替换字符串中指定字符或空格或 等
去掉字符串中空格:

public static void main(String args[]){    String str = "aaaaaaaaabbbbbbaaaaaaaa";    String test = str.replaceAll("b", "c");    System.out.println(test);}