如何替换字符串中的多个子字符串实例(How to replace multiple instances of substring within a string)

 我需要在同一个地方替换不同内容的大字符串的一些内容。 
 
 可以说我有一个字符串： 
 
String str = "package blah.foo.bar;\n"
           + "import org.blah.blah;\n"
           + "import sel.this.that;\n"
           + "import sel.boo.foo;\n"
           + "...more text";
 
 我想将单词gen插入以import sel.开头的语句中import sel. 所以最终结果如下： import sel.gen.this.that; 
 
 我已经成功使用以下方法，但只有当我知道子字符串将在字符串中的位置时。 我的问题是，我不确定如何使以下代码动态： 
 
private String modifyString(String str){
    String hold = str.substring(0, str.indexOf(";"));
    hold = new StringBuilder(hold).insert(13, "gen.").toString();
    str = str.replace("(?m)^package.*", hold);
    return str;

}
 
 上面的代码正确地替换了字符串package blah.foo.bar; 与package blah.gen.foo.bar; 
 
 但这又一次只能替换字符串的开头部分。 我希望能够保存子字符串的所有实例，然后在这些子字符串中插入子字符串。 

I need to replace some of the contents of a large string with different content in the same spot.
 
Lets say I have a string:
 
String str = "package blah.foo.bar;\n"
           + "import org.blah.blah;\n"
           + "import sel.this.that;\n"
           + "import sel.boo.foo;\n"
           + "...more text";
 
I want to insert the word gen into statements which start with import sel. So that the end result looks like: import sel.gen.this.that;
 
I have had success with the following method but only when I KNOW where that substring will be within the string. My issue is that I'm not sure how to make the following code dynamic:
 
private String modifyString(String str){
    String hold = str.substring(0, str.indexOf(";"));
    hold = new StringBuilder(hold).insert(13, "gen.").toString();
    str = str.replace("(?m)^package.*", hold);
    return str;

}
 
The above code correctly replaces the strings package blah.foo.bar; with package blah.gen.foo.bar;
 
But again this only works with replacing the beginning portion of the string. I'm looking to be able to hold all instances of a substring and then insert a substring within those substrings.

原文：https://stackoverflow.com/questions/34344616