如何在StringBuilder中连接子字符串？

Question

How can I refactor substring concatenations to StringBuilder ?

        String line = "this is my start and my end string";
        int start = line.indexOf("start");
        line = line.substring(0, start) + line.substring(start + 5);

        int end = line.indexOf("end");
        line = line.substring(0, end) + line.substring(end + 3);
            //result: this is my and my string";

How would the same code look like with StringBuilder? When I want to execute substrings several times one after the other?

Answer 1

If your question is "How do I repeatedly remove substrings from a string", you might try something like this:

StringBuilder line = new StringBuilder("this is my start and my end string");
int start = line.indexOf("start");
line.delete(start, start + 5);
int end = line.indexOf("end");
line.delete(end, end + 3);
String result = sb.toString()

Create the StringBuilder once, and then manipulate its contents.

Answer 2

Something like this may be:

    StringBuilder line = new StringBuilder("this is my **start** and my **end** string");
    int start = line.indexOf("start");
    line = new StringBuilder(line.substring(0, start).append(line.substring(start + 5)));

    int end = line.indexOf("end");
    line = new StringBuilder(line.substring(0, end).append(line.substring(end + 3)));

Answer 3

Something like this you mean? Or have I understood it wrong?

String line = "this is my start and my end string";
int start = line.indexOf("start");
int end = line.indexOf("end");
StringBuilder sb = new StringBuilder();
sb.append(line.substring(0, start);
sb.append(line.substring(start + 5);
sb.append(line.substring(0, end);
sb.append(line.substring(end + 3);
String result = sb.toString()

Answer 4

Try

String line = "this is my start and my end string";
    int start = line.indexOf("start");
    StringBuilder stringBuilder = new StringBuilder();
    stringBuilder.append(line.substring(0, start));
    stringBuilder.append(line.substring(start + 5));

    int end = line.indexOf("end");
    stringBuilder.append(line.substring(0, end));
    stringBuilder.append(line.substring(end + 3));
    System.out.println("StringBuilder : "+stringBuilder.toString());

Answer 5

StringBuilder has it's Own indexOf and substring implementations if i am not wrong. The primary concern of the question seems to discard the use of String, and main features of StringBuilder are still concatenations.

So http://docs.oracle.com/javase/7/docs/api/java/lang/StringBuilder.html can help you find relevant methods, and you can go on using StringBuilder with .append() method and ur string finding and substring methods.