建立一个android工程，修改main.xml文件并编写程序代码，用SQLite编写一个学生信息管理应用，并实现插入、删除、更新、查找等方法

好的，下面是一个简单的示例代码，仅供参考：

1. 在主Activity中创建SQLiteOpenHelper的子类，例如：

public class StudentDatabaseHelper extends SQLiteOpenHelper {

    private static final String DATABASE_NAME = "student.db";
    private static final int DATABASE_VERSION = 1;

    private static final String TABLE_NAME = "student";
    private static final String COLUMN_ID = "id";
    private static final String COLUMN_NAME = "name";
    private static final String COLUMN_AGE = "age";

    public StudentDatabaseHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        String CREATE_TABLE = "CREATE TABLE " + TABLE_NAME + "("
                + COLUMN_ID + " INTEGER PRIMARY KEY AUTOINCREMENT,"
                + COLUMN_NAME + " TEXT,"
                + COLUMN_AGE + " INTEGER" + ")";
        db.execSQL(CREATE_TABLE);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME);
        onCreate(db);
    }

    public long insertStudent(String name, int age) {
        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues values = new ContentValues();
        values.put(COLUMN_NAME, name);
        values.put(COLUMN_AGE, age);
        long id = db.insert(TABLE_NAME, null, values);
        db.close();
        return id;
    }

    public int updateStudent(long id, String name, int age) {
        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues values = new ContentValues();
        values.put(COLUMN_NAME, name);
        values.put(COLUMN_AGE, age);
        int rowsAffected = db.update(TABLE_NAME, values, COLUMN_ID + " = ?",
                new String[] { String.valueOf(id) });
        db.close();
        return rowsAffected;
    }

    public int deleteStudent(long id) {
        SQLiteDatabase db = this.getWritableDatabase();
        int rowsAffected = db.delete(TABLE_NAME, COLUMN_ID + " = ?",
                new String[] { String.valueOf(id) });
        db.close();
        return rowsAffected;
    }

    public Cursor getAllStudents() {
        SQLiteDatabase db = this.getReadableDatabase();
        Cursor cursor = db.query(TABLE_NAME, null, null, null, null, null, null);
        return cursor;
    }

    public Cursor searchStudentByName(String name) {
        SQLiteDatabase db = this.getReadableDatabase();
        Cursor cursor = db.query(TABLE_NAME, null, COLUMN_NAME + " LIKE ?",
                new String[] { "%" + name + "%" }, null, null, null);
        return cursor;
    }
}

2. 在主Activity中定义UI界面的组件，例如：

public class MainActivity extends AppCompatActivity {
    private EditText editTextName;
    private EditText editTextAge;
    private Button buttonAdd;
    private Button buttonUpdate;
    private Button buttonDelete;
    private Button buttonSearch;
    private ListView listView;

    private SimpleCursorAdapter adapter;
    private StudentDatabaseHelper dbHelper;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        dbHelper = new StudentDatabaseHelper(this);
        editTextName = findViewById(R.id.editTextName);
        editTextAge = findViewById(R.id.editTextAge);
        buttonAdd = findViewById(R.id.buttonAdd);
        buttonUpdate = findViewById(R.id.buttonUpdate);
        buttonDelete = findViewById(R.id.buttonDelete);
        buttonSearch = findViewById(R.id.buttonSearch);
        listView = findViewById(R.id.listView);

        String[] fromColumns = { StudentDatabaseHelper.COLUMN_NAME, StudentDatabaseHelper.COLUMN_AGE };
        int[] toViews = { android.R.id.text1, android.R.id.text2 };
        adapter = new SimpleCursorAdapter(this,
                android.R.layout.simple_list_item_2, null, fromColumns, toViews, 0);
        listView.setAdapter(adapter);

        buttonAdd.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String name = editTextName.getText().toString().trim();
                int age = Integer.parseInt(editTextAge.getText().toString().trim());
                long id = dbHelper.insertStudent(name, age);
                if (id > 0) {
                    Toast.makeText(MainActivity.this, "添加成功", Toast.LENGTH_SHORT).show();
                    refreshListView();
                } else {
                    Toast.makeText(MainActivity.this, "添加失败", Toast.LENGTH_SHORT).show();
                }
            }
        });

        buttonUpdate.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                long id = listView.getSelectedItemId();
                if (id == AdapterView.INVALID_ROW_ID) {
                    Toast.makeText(MainActivity.this, "请选中一条记录", Toast.LENGTH_SHORT).show();
                    return;
                }
                String name = editTextName.getText().toString().trim();
                int age = Integer.parseInt(editTextAge.getText().toString().trim());
                int rowsAffected = dbHelper.updateStudent(id, name, age);
                if (rowsAffected > 0) {
                    Toast.makeText(MainActivity.this, "更新成功", Toast.LENGTH_SHORT).show();
                    refreshListView();
                } else {
                    Toast.makeText(MainActivity.this, "更新失败", Toast.LENGTH_SHORT).show();
                }
            }
        });

        buttonDelete.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                long id = listView.getSelectedItemId();
                if (id == AdapterView.INVALID_ROW_ID) {
                    Toast.makeText(MainActivity.this, "请选中一条记录", Toast.LENGTH_SHORT).show();
                    return;
                }
                int rowsAffected = dbHelper.deleteStudent(id);
                if (rowsAffected > 0) {
                    Toast.makeText(MainActivity.this, "删除成功", Toast.LENGTH_SHORT).show();
                    refreshListView();
                } else {
                    Toast.makeText(MainActivity.this, "删除失败", Toast.LENGTH_SHORT).show();
                }
            }
        });

        buttonSearch.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String name = editTextName.getText().toString().trim();
                Cursor cursor = dbHelper.searchStudentByName(name);
                adapter.changeCursor(cursor);
            }
        });

        refreshListView();
    }

    private void refreshListView() {
        Cursor cursor = dbHelper.getAllStudents();
        adapter.changeCursor(cursor);
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        dbHelper.close();
    }
}

3. 在布局文件（例如activity_main.xml）中定义UI界面的组件，例如：

<EditText
    android:id="@+id/editTextName"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:hint="姓名" />

<EditText
    android:id="@+id/editTextAge"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:hint="年龄" />

<Button
    android:id="@+id/buttonAdd"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="添加" />

<Button
    android:id="@+id/buttonUpdate"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="更新" />

<Button
    android:id="@+id/buttonDelete"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="删除" />

<Button
    android:id="@+id/buttonSearch"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="查找" />

<ListView
    android:id="@+id/listView"
    android:layout_width="match_parent"
    android:layout_height="wrap_content" />

需要注意的是，由于SQLite数据库的操作需要在后台线程中进行，因此可以使用AsyncTask等异步任务框架来实现。此外，为了提高查询效率，可以在数据库中创建索引。