A modifiable sequence of characters for use in creating strings, where all accesses are synchronized. This class has mostly been replaced by StringBuilder because this synchronization is rarely useful. This class is mainly used to interact with legacy APIs that expose it.

一個可以修改的字串序列用來建立字串，這個類大多被StringBuilder替代，因為同步很少又有。這個類主要為以前的API相相容。

For particularly complex string-building needs, consider Formatter.

The majority of the modification methods on this class return this so that method calls can be chained together. For example: new StringBuffer("a").append("b").append("c").toString().

See Also

CharSequence

Appendable

StringBuilder

String

format(String, Object...)

舉例：

//建立一個StringBuffer

StringBuffer sb = new StringBuffer();

String line = null;

BufferedReader buffer = null;

try {

 //根據給定字串建立URL

 url = new URL(urlstr);

 //根據URL建立Http URL連線

 HttpURLConnection urlConn = (HttpURLConnection)url.openConnection();

 //根據Http URL的輸入流先建立InputStreamReader，然後由InputStreamReader建立一個BufferedReader。

 buffer = new BufferedReader(new InputStreamReader(urlConn.getInputStream()));

 //有BufferedReader的物件迴圈讀取 每一行資料，並將所有資料放到StringBuffer儲存起來

 while((line = buffer.readLine()) != null){

  sb.append(line);

 }

} catch (Exception e) {

 // TODO: handle exception

 e.printStackTrace();

}finally{

 try {

  buffer.close();

 } catch (Exception e) {

  // TODO: handle exception

  e.printStackTrace();

 }

 //檔案讀取完畢，最後返回讀到的內容

 return sb.toString();

  }