1.空间的ID只在当前的xml布局文件里是唯一的，在不同的xml布局文件中可以重复；
一、数据库的Cursor
对于Android SQLite数据库封装的查询返回对象Cursor来说比较容易出错的有
1. Cursor返回可能为null
如果query返回的Cursor对象为空，执行cursor的任何方法肯定有空指针异常了，这点Android的代码有40%都没有注意到。
2. Cursor返回为0
我们仅仅判断不为空还不行，如果Cursor的对象为0，执行了moveToFirst(); 这样的方法就比较尴尬了，这点Android开发网格外提示大家注意。
3. 遍历Cursor时没有执行moveToFirst()，这样游标的位置就不确定了。
4. Cursor使用完后要手动关闭，cursor.close()这个方法不要忘记了。
5. Cursor的类型获取，比如说getInt和getLong，由于在SQLite中boolean和long型均为SQLite的Integer所以，读取时一定记住转换。
//调用浏览器
Uri uri = Uri.parse("");
Intent it = new Intent(Intent.ACTION_VIEW,uri);
startActivity(it);
//显示某个坐标在地图上
Uri uri = Uri.parse("geo:38.899533,-77.036476");
Intent it = new Intent(Intent.Action_VIEW,uri);
startActivity(it);
//显示路径
Uri uri = Uri.parse("http://maps.google.com/maps?f=d&saddr=startLat%20startLng&daddr=endLat%20endLng&hl=en");
Intent it = new Intent(Intent.ACTION_VIEW,URI);
startActivity(it);
//拨打电话
Uri uri = Uri.parse("tel:10086");
Intent it = new Intent(Intent.ACTION_DIAL, uri);
startActivity(it);
Uri uri = Uri.parse("tel.10086");
Intent it =new Intent(Intent.ACTION_CALL,uri);
需要添加 <uses-permission id="android.permission.CALL_PHONE" /> 这个权限到androidmanifest.xml
//发送短信或彩信
Intent it = new Intent(Intent.ACTION_VIEW);
it.putExtra("sms_body", "The SMS text");
it.setType("vnd.android-dir/mms-sms");
startActivity(it);
//发送短信
Uri uri = Uri.parse("smsto:10086");
Intent it = new Intent(Intent.ACTION_SENDTO, uri);
it.putExtra("sms_body", "cwj");
startActivity(it);
//发送彩信
Uri uri = Uri.parse("content://media/external/images/media/23");
Intent it = new Intent(Intent.ACTION_SEND);
it.putExtra("sms_body", "some text");
it.putExtra(Intent.EXTRA_STREAM, uri);
it.setType("image/png");
startActivity(it);
//发送邮件
Uri uri = Uri.parse("mailto:android123@163.com");
Intent it = new Intent(Intent.ACTION_SENDTO, uri);
startActivity(it);
Intent it = new Intent(Intent.ACTION_SEND);
it.putExtra(Intent.EXTRA_EMAIL, android123@163.com);
it.putExtra(Intent.EXTRA_TEXT, "The email body text");
it.setType("text/plain");
startActivity(Intent.createChooser(it, "Choose Email Client"));
Intent it=new Intent(Intent.ACTION_SEND);
String[] tos={"me@abc.com"};
String[] ccs={"you@abc.com"};
it.putExtra(Intent.EXTRA_EMAIL, tos);
it.putExtra(Intent.EXTRA_CC, ccs);
it.putExtra(Intent.EXTRA_TEXT, "The email body text");
it.putExtra(Intent.EXTRA_SUBJECT, "The email subject text");
it.setType("message/rfc822");
startActivity(Intent.createChooser(it, "Choose Email Client"));
//播放媒体文件
Intent it = new Intent(Intent.ACTION_VIEW);
Uri uri = Uri.parse("file:///sdcard/cwj.mp3");
it.setDataAndType(uri, "audio/mp3");
startActivity(it);
Uri uri = Uri.withAppendedPath(MediaStore.Audio.Media.INTERNAL_CONTENT_URI, "1");
Intent it = new Intent(Intent.ACTION_VIEW, uri);
startActivity(it);
//卸载APK
Uri uri = Uri.fromParts("package", strPackageName, null);
Intent it = new Intent(Intent.ACTION_DELETE, uri);
startActivity(it);
//卸载apk 2
Uri uninstallUri = Uri.fromParts("package", "xxx", null);
returnIt = new Intent(Intent.ACTION_DELETE, uninstallUri);
//安装APK
Uri installUri = Uri.fromParts("package", "xxx", null);
returnIt = new Intent(Intent.ACTION_PACKAGE_ADDED, installUri);
//播放音乐
Uri playUri = Uri.parse("file:///sdcard/download/sth.mp3");
returnIt = new Intent(Intent.ACTION_VIEW, playUri);
//发送附近
Intent it = new Intent(Intent.ACTION_SEND);
it.putExtra(Intent.EXTRA_SUBJECT, "The email subject text");
it.putExtra(Intent.EXTRA_STREAM, "file:///sdcard/cwj.mp3");
sendIntent.setType("audio/mp3");
startActivity(Intent.createChooser(it, "Choose Email Client"));
//market上某个应用信，pkg_name就是应用的packageName
Uri uri = Uri.parse("market://search?q=pname:pkg_name");
Intent it = new Intent(Intent.ACTION_VIEW, uri);
startActivity(it);
//market上某个应用信息，app_id可以通过www网站看下
Uri uri = Uri.parse("market://details?id=app_id");
Intent it = new Intent(Intent.ACTION_VIEW, uri);
startActivity(it);
//调用搜索
Intent intent = new Intent();
intent.setAction(Intent.ACTION_WEB_SEARCH);
intent.putExtra(SearchManager.QUERY,"android123")
startActivity(intent);