使用indexof在字符串中查找模式

Question

Can someone tell me why this is an infinte loop?

private void splitBody()    {
        bodyparts=new Vector();
        String body = "<br />testtestest<br />fefefefefefefefefef<br />qqqqqqqqqqqq";

        int previousIndex=0;
        while(body.indexOf("<br />",previousIndex)!=-1) {
            int index=body.indexOf("<br />",previousIndex);
            System.out.println(body.substring(previousIndex, index));
            bodyparts.addElement(body.substring(previousIndex, index));
            previousIndex=index;
        }
    }

Answer 1

将最后一行更改为：

previousIndex = index + 1;

Answer 2

Because you don't change your body string, so indexOf always returns an index different that -1 since the substring is contained in body .

Add body = body.substring(index); at the end of the loop to fix that.

Answer 3

This should fix the issue:

previousIndex=index + 1;

Otherwise you'll always find the first occurance of the pattern.

Or - simplify the whole thing:

String[] parts = body.split("<br />");

Answer 4

The indexOf operation return the starting position. If you want to move forward, increment the previousIndex like this.

  bodyparts=new Vector();
  String body = "<br />testtestest<br />fefefefefefefefefef<br />qqqqqqqqqqqq";

  int previousIndex=0;
  while(body.indexOf("<br />",previousIndex)!=-1) {
    int index=body.indexOf("<br />",previousIndex);
    System.out.println(body.substring(previousIndex, index));
    bodyparts.addElement(body.substring(previousIndex, index));
    previousIndex=index+("<br />".size());
  }