如果想得到一个Cursor, 而此时又没有数据库返回一个Cursor，此时可以通过MatrixCursor来返回一个伪造的Cursor。比如一个程序在一般情况下用getContentReslover.query从数据库查询数据，但是在很特殊的某条件下，需要返回的只是几条固定的已知记录，不需要从数据库查询，但是为了最终结果能被调用他的方法使用，我们还是希望返回的是Cursor，那么就需要MatrixCursor根据这些已知的记录来构造一个Cursor。
也许这里有一个疑问：为什么Cursor自己不能构造一些数据呢？
因为Cursor只是一个interface，不是一个具体的类，getContentReslover.query返回的其实也不是Cursor而是Cursor的一种实现。
_id | name | price |
R.drawable.ic_launcher | row1 | 39 |
R.drawable.ic_launcher | row2 | 40 |
R.drawable.ic_launcher | row3 | 41 |
R.drawable.ic_launcher | row4 | 42 |
泡在网上的日子package com.test.matrixcursor;
import android.app.ListActivity;
import android.database.MatrixCursor;
import android.os.Bundle;
import android.support.v4.widget.SimpleCursorAdapter;
import android.view.View;
import android.widget.ListView;
import android.widget.Toast;
public class MainActivity extends ListActivity {
private static final String[] COLUMN_NAME = { "_id", "name", "price" };
private MatrixCursor matrixCursor;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
createList();
//createList2();
}
private void createList() {
matrixCursor = new MatrixCursor(COLUMN_NAME, 1);
matrixCursor.addRow(new Object[] { R.drawable.ic_launcher, "row1",
39 });
matrixCursor
.addRow(new Object[] { R.drawable.ic_launcher, "row2", 40 });
matrixCursor
.addRow(new Object[] { R.drawable.ic_launcher, "row3", 41 });
matrixCursor.addRow(new Object[] { R.drawable.ic_launcher, "row4",
42 });
matrixCursor
.addRow(new Object[] { R.drawable.ic_launcher, "row5", 43 });
setListAdapter(new SimpleCursorAdapter(this, R.layout.activity_main,
matrixCursor, COLUMN_NAME, new int[] { R.id.icon, R.id.name,
R.id.price }));
}
//第二种添加row的方式
private void createList2() {
matrixCursor = new MatrixCursor(COLUMN_NAME, 1);
MatrixCursor.RowBuilder builder1 = matrixCursor.newRow();
builder1.add(R.drawable.ic_launcher);
builder1.add("row1");
builder1.add(39);
MatrixCursor.RowBuilder builder2 = matrixCursor.newRow();
builder2.add(R.drawable.ic_launcher);
builder2.add("row2");
builder2.add(40);
MatrixCursor.RowBuilder builder3 = matrixCursor.newRow();
builder3.add(R.drawable.ic_launcher);
builder3.add("row3");
builder3.add(41);
setListAdapter(new SimpleCursorAdapter(this, R.layout.activity_main,
matrixCursor, COLUMN_NAME, new int[] { R.id.icon, R.id.name,
R.id.price }));
}
@Override
protected void onListItemClick(ListView l, View v, int position, long id) {
super.onListItemClick(l, v, position, id);
matrixCursor.moveToPosition(position);
StringBuilder builder = new StringBuilder();
builder.append("Name:")
.append(matrixCursor.getString(matrixCursor
.getColumnIndex("name"))).append("\n");
builder.append("Price:")
.append(matrixCursor.getString(matrixCursor
.getColumnIndex("price"))).append("\n");
Toast.makeText(getApplicationContext(), builder.toString(), 1000)
.show();
}
}MatrixCursor matrixCursor=new MatrixCursor(COLUMN_NAME);
matrixCursor = new MatrixCursor(COLUMN_NAME, 10);
matrixCursor.addRow(new Object[] { R.drawable.ic_launcher, "zhangsan",39 });MatrixCursor.RowBuilder builder1 = matrixCursor.newRow();
builder1.add(R.drawable.ic_launcher);
builder1.add("zhangsan");
builder1.add(39);
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