//讀寫檔案函式呼叫
writeFileData(filename,datas);
String result=readFileData(filename);
Toast.makeText(Main2Activity.this,result.getClass().toString(),Toast.LENGTH_SHORT).show();

下面是讀寫程式碼的實現：

//檔案寫入
    public void writeFileData(String filename, String content){
        try {
            FileOutputStream fos 
 
= this.openFileOutput(filename, MODE_PRIVATE);//獲得FileOutputStream
            //將要寫入的字串轉換為byte陣列
            byte[]  bytes = content.getBytes();
            fos.write(bytes);//將byte陣列寫入檔案
            fos.close();//關閉檔案輸出流

        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    
 
//檔案讀取
    public String readFileData(String fileName){
        String result="";
        try{
            FileInputStream fis = openFileInput(fileName);
            //獲取檔案長度
            int lenght = fis.available();
            byte[] buffer = new byte[lenght];
            fis.read(buffer);
            
 
//將byte陣列轉換成指定格式的字串
            result = new String(buffer, "UTF-8");

        } catch (Exception e) {
            e.printStackTrace();
        }
        return  result;
    }