讀寫記憶卡文字檔

以下是Android讀寫記憶卡檔案的程式碼
[sea:javaCode]
                String str = "Write Test";
                try {
                    if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){
                        File ofe = new File(Environment.getExternalStorageDirectory()+"/test.txt");
                        if(!ofe.exists())
                        ofe.createNewFile();
                        // write string
                        FileWriter fo = new FileWriter(ofe);
                        fo.write(str);
                        // read to string
                        FileReader fi = new FileReader(ofe);
                        fi.read(str.toCharArray());
                        vtext.setText(str);
                    }else{
                        vtext.setText("Not SD Card");
                    }
                }catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
[/sea]

這斷程式碼特別需要注意
[sea:javaCode]
if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){
...
}
[/sea]
這是判斷Android是否有安裝記憶卡
要用equals來判斷，如果寫成以下方式是無法成功判別的
[sea:javaCode]
if(Environment.getExternalStorageState()==Environment.MEDIA_MOUNTED){
...
}
[/sea]