android学生信息管理系统，完善数据删除功能

package com.vanceinfo.stus; import android.app.AlertDialog; import android.app.ListActivity; import android.content.DialogInterface; import android.content.Intent; import android.database.Cursor; import android.database.sqlite.SQLiteDatabase; import android.graphics.Bitmap.Config; import android.os.Bundle; import android.view.ContextMenu; import android.view.ContextMenu.ContextMenuInfo; import android.view.Menu; import android.view.MenuItem; import android.view.View; import android.view.View.OnClickListener; import android.widget.AdapterView; import android.widget.AdapterView.AdapterContextMenuInfo; import android.widget.AdapterView.OnItemClickListener; import android.widget.AdapterView.OnItemLongClickListener; import android.widget.Button; import android.widget.ListView; import android.widget.SimpleCursorAdapter; import android.widget.TextView; import com.vanceinfo.stus.StudentDbAdapter.DatabaseHelper; public class ActivityStudents extends ListActivity implements OnClickListener, OnItemClickListener, OnItemLongClickListener { private static final int ACTIVITY_CREATE = 0; private static final int ACTIVITY_EDIT = 1; private static final int ACTIVITY_QUERY = 2; private ListView listView; private StudentDbAdapter sDbAdapter; private Cursor sStudentCursor; private String test; //查询时输入的内容 private static final int INSERT_ID = Menu.FIRST; private static final int DELETE_ID = Menu.FIRST + 1; private static final int QUERY_ID = Menu.FIRST + 2; private static final int INSERT_ID1 = Menu.FIRST + 3; private static final int QUERY_ID1 = Menu.FIRST + 4; public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.mainpara); sDbAdapter = new StudentDbAdapter(this); sDbAdapter.open(); listView = getListView(); getListView().addHeaderView(buildHeader()); getListView().addHeaderView(buildHeaderTitle()); getListView().addFooterView(buildFooter()); getListView().addFooterView(buildFooterRefresh()); renderListView(0); listView.setOnCreateContextMenuListener(this); listView.setOnItemLongClickListener(this); } //根据查询内容的不同调用不同查询语句 private void renderListView(int x) { switch (x) { case 0: sStudentCursor = sDbAdapter.getAllStudents(); break; case 1: sStudentCursor = sDbAdapter.getAllStudentsByName(); break; case 2: sStudentCursor = sDbAdapter.getAllStudentsByNumber(); break; case 3: sStudentCursor = sDbAdapter.getStudentByName(test); break; case 4: sStudentCursor = sDbAdapter.getStudentByNumber(test); break; default: setTitle("出错了"); } startManagingCursor(sStudentCursor); String[] from = new String[] { StudentDbAdapter.KEY_NAME, StudentDbAdapter.KEY_SEX , StudentDbAdapter.KEY_NUMBER }; int[] to = new int[] { R.id.name_text, R.id.sex_text, R.id.number_text}; SimpleCursorAdapter stu = new SimpleCursorAdapter(this, R.layout.student_row, sStudentCursor, from, to); setListAdapter(stu); } private View buildHeaderTitle() { TextView tx = new TextView (this); tx.setText("姓名 性别 学号 icon"); return tx; } //姓名排序 按钮 以及其监听器 private View buildHeader() { Button btn1=new Button(this); btn1.setText("按姓名排序"); btn1.setOnClickListener(new Button.OnClickListener() { @Override public void onClick(View v) { renderListView(1); } }); return btn1; } private View buildFooter() { Button btn2=new Button(this); btn2.setText("按学号排序"); btn2.setOnClickListener(new Button.OnClickListener() { @Override public void onClick(View v) { renderListView(2); } }); return btn2; } //刷新按钮 private View buildFooterRefresh() { Button btn2=new Button(this); btn2.setText("全部学生信息"); btn2.setOnClickListener(new Button.OnClickListener() { @Override public void onClick(View v) { renderListView(0); } }); return btn2; } @Override public void onCreateContextMenu(ContextMenu menu, View v, ContextMenuInfo menuInfo) { menu.add(1,INSERT_ID, 1, "添加信息"); menu.add(1,DELETE_ID, 1, "删除信息"); menu.add(1, QUERY_ID, 1, "查询信息"); } public boolean onCreateOptionsMenu(Menu menu) { super.onCreateOptionsMenu(menu); menu.add(0, INSERT_ID1, 0, "添加"); //menu.add(0, DELETE_ID, 0, "删除"); menu.add(0, QUERY_ID1, 0, "查询"); return true; } public boolean onMenuItemSelected(int featureId, MenuItem item){ { switch (item.getItemId()) { case INSERT_ID1: createStudent (); return true; /*case DELETE_ID: sDbAdapter.deleteStudent(getListView().getSelectedItemId()); renderListView(0); return true;*/ case QUERY_ID1: queryStudent (); return true; } return super.onMenuItemSelected(featureId, item);} } //menu public boolean onContextItemSelected(MenuItem item) { AdapterContextMenuInfo info = (AdapterContextMenuInfo) item .getMenuInfo(); int index = (int) info.id; switch (item.getItemId()) { case INSERT_ID: createStudent (); return true; case DELETE_ID: sDbAdapter.deleteStudent(index); renderListView(0); return true; case QUERY_ID: queryStudent (); return true; } return super.onContextItemSelected(item); } private void queryStudent() { Intent i = new Intent(this, ActivityQuery.class); startActivityForResult(i, ACTIVITY_QUERY); //startActivity(i); } private void createStudent() { Intent i = new Intent(this, ActivityEdit.class); startActivityForResult(i, ACTIVITY_CREATE); } /*// 删除数据 public void deleteData(String id){ DatabaseHelper dbHelper = new DatabaseHelper(ActivityStudents.this,sDbAdapter.DATABASE_NAME); SQLiteDatabase sdb = dbHelper.getWritableDatabase(); sdb.delete(sDbAdapter.DATABASE_NAME, " _id=?", new String[]{id}); //删除数据 } *//** * 删除操作 *//* public void alertDeleteOpt(final String id){ new AlertDialog.Builder(this) .setCancelable(false) .setMessage("您确定要删除这条信息吗？") .setPositiveButton("确定", new DialogInterface.OnClickListener() { public void onClick(DialogInterface dialog, int which) { deleteData(id); }}) .setNegativeButton("取消", new DialogInterface.OnClickListener() { public void onClick(DialogInterface dialog, int which) { dialog.cancel(); }}) .show(); }*/ // 需要对position和id进行一个很好的区分 // position指的是点击的这个ViewItem在当前ListView中的位置 // 每一个和ViewItem绑定的数据，肯定都有一个id，通过这个id可以找到那条数据。 protected void onListItemClick(ListView l, View v, int position, long id) { super.onListItemClick(l, v, position, id); Cursor c = sStudentCursor; c.moveToPosition(position-2); //将数据库中的id与实际位置相对应，由于添加Headerview导致实际位置+2 Intent i = new Intent(this, ActivityEdit.class); i.putExtra(StudentDbAdapter.KEY_ROWID, id); i.putExtra(StudentDbAdapter.KEY_NAME, c.getString(c .getColumnIndexOrThrow(StudentDbAdapter.KEY_NAME))); i.putExtra(StudentDbAdapter.KEY_SEX, c.getString(c .getColumnIndexOrThrow(StudentDbAdapter.KEY_SEX))); i.putExtra(StudentDbAdapter.KEY_NUMBER, c.getString(c .getColumnIndexOrThrow(StudentDbAdapter.KEY_NUMBER))); startActivityForResult(i, ACTIVITY_EDIT); } protected void onActivityResult(int requestCode, int resultCode, Intent intent) { renderListView(0); if(resultCode ==ACTIVITY_QUERY) { test=intent.getStringExtra("num"); String radiobutton = intent.getStringExtra("selected"); if(radiobutton.equals("name")) { renderListView(3); }else if(radiobutton.equals("number")) {