实现步骤仅需3步,下面通过字符数组来说明:
步骤1.首先创建一个字符数组,且字符数组的值对应着表的字段,如下:
String[] COLUMN_NAME = { "_id", "name", "price" };
步骤2.利用MatrixCursor的构造方法,构造一个MatrixCursor,传入的参数即是步骤1中创建的字段数组,如下:
MatrixCursormatrixCursor=newMatrixCursor(COLUMN_NAME);
也可以指定初始大小,如:
matrixCursor=newMatrixCursor( COLUMN_NAME,
10);
步骤3. 通过matrixCursor 的addRow方法添加一行值,相当于向数据库中插入一条记录,如下:
matrixCursor.addRow(new Object[] { R.drawable.ic_launcher, "zhangsan",39 });
注:步骤3也可以通过构造一个MatrixCursor.RowBuilder来实现,也是相当于向数据库中插入一条记录,如下:
MatrixCursor.RowBuilder builder1 = matrixCursor.newRow();
builder1.add(R.drawable.ic_launcher);
builder1.add("zhangsan");
builder1.add(39);
//builder1.add(399999);
通过上面三步即可完成MatrixCursor 的构造。从MatrixCursor 中取出数据的过程与Cursor相同,不再赘述!
注释:如果builder1对象add的数量大于字段的个数,即打开builder1.add(399999);注释,那么将会报以下错误:
02-27 19:00:44.882: W/dalvikvm(29036): threadid=1: thread exiting with uncaught exception (group=0x41e689a8)
02-27 19:00:44.882: W/dalvikvm(29036): threadid=1: uncaught exception occurred
02-27 19:00:44.883: W/System.err(29036): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.test.matrixcursor/com.test.matrixcursor.MainActivity}:android.database.CursorIndexOutOfBoundsException: No more
columns left.
02-27 19:00:44.883: W/System.err(29036): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2356)
02-27 19:00:44.883: W/System.err(29036): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2408)
02-27 19:00:44.883: W/System.err(29036): at android.app.ActivityThread.access$600(ActivityThread.java:167)
02-27 19:00:44.883: W/System.err(29036): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1378)
02-27 19:00:44.883: W/System.err(29036): at android.os.Handler.dispatchMessage(Handler.java:107)
02-27 19:00:44.883: W/System.err(29036): at android.os.Looper.loop(Looper.java:194)
02-27 19:00:44.884: W/System.err(29036): at android.app.ActivityThread.main(ActivityThread.java:5405)
02-27 19:00:44.884: W/System.err(29036): at java.lang.reflect.Method.invokeNative(Native Method)
02-27 19:00:44.884: W/System.err(29036): at java.lang.reflect.Method.invoke(Method.java:525)
02-27 19:00:44.884: W/System.err(29036): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:838)
02-27 19:00:44.884: W/System.err(29036): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:605)
02-27 19:00:44.884: W/System.err(29036): at dalvik.system.NativeStart.main(Native Method)
02-27 19:00:44.886: W/System.err(29036): Caused by: android.database.CursorIndexOutOfBoundsException: No more columns left.
02-27 19:00:44.887: W/System.err(29036): at android.database.MatrixCursor$RowBuilder.add(MatrixCursor.java:206)
02-27 19:00:44.887: W/System.err(29036): at com.test.matrixcursor.MainActivity.createList(MainActivity.java:46)
02-27 19:00:44.888: W/System.err(29036): at com.test.matrixcursor.MainActivity.onCreate(MainActivity.java:20)
02-27 19:00:44.889: W/System.err(29036): at android.app.Activity.performCreate(Activity.java:5127)
02-27 19:00:44.889: W/System.err(29036): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1151)
02-27 19:00:44.890: W/System.err(29036): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2320)
程序运行结果: