Java替换字符串中的字符，但变量中的给定值除外

Need some help. So here is the task: Create a program that will ask for a main phrase. Ask for a key string value that will be preserved in the phrase. Display a version of the original main phrase where all chars have been replaced by pluses ("+"), except for appearances of the key string value which are preserved unchanged. Sample outputs:Need some help. So here is the task: Create a p