public class MainActivity extends Activity {	public boolean flag = false;	public TextView textview;	public String FILE_NAME="SharedPreferences";//存储数据的唯一标识	@Override	protected void onCreate(Bundle savedInstanceState) {		super.onCreate(savedInstanceState);		setContentView(R.layout.activity_main);		textview = (TextView)findViewById(R.id.textview);		init();	}		public void init(){				/*		 * Android中的文件存储，当第一次取数据时如果还没有存入数据，将返回默认数据		 */				SharedPreferences sharedPreferences = getSharedPreferences(FILE_NAME, Context.MODE_PRIVATE);		//从文件中获取保存的数据		String usernameContent = sharedPreferences.getString("username", "默认数据");		textview.setText(usernameContent);				/*		SharedPreferences sp = getSharedPreferences(FILE_NAME, Context.MODE_PRIVATE);		Editor editor = sp.edit();		editor.clear();		editor.putString("name", "正常数据");		editor.commit();		String name = sp.getString("name", "默认数据");		textview.setText(name);		*/	}	}