安卓编程题

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="20dp">

    <Button
        android:id="@+id/btn_one"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:text="按钮1" />

    <Button
        android:id="@+id/btn_two"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="260dp"
        android:text="按钮2" />

    <Button
        android:id="@+id/btn_three"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignBottom="@id/btn_two"
        android:layout_marginBottom="100dp"
        android:layout_toRightOf="@id/btn_two"
        android:text="按钮3" />
</RelativeLayout>

隐式

 

这道题考的是查询，也可能考其他的功能 （增删改查）

@Override
    public void onClick(View v) {
        String name, phone;
        SQLiteDatabase db;
        ContentValues values;
        switch (v.getId()) {
            case R.id.btn_query: //查询数据
                db = myHelper.getReadableDatabase();
                Cursor cursor = db.query("information", null, null, null, null,
                        null, null);
                if (cursor.getCount() == 0) {
                    mTvShow.setText("");
                    Toast.makeText(this, "没有数据", Toast.LENGTH_SHORT).show();
                } else {
                    cursor.moveToFirst();
                    mTvShow.setText("Name :  " + cursor.getString(1) +
                            "  ；Tel :  " + cursor.getString(2));
                }
                while (cursor.moveToNext()) {
                    mTvShow.append("\n" + "Name :  " + cursor.getString(1) +
                            "  ；Tel :  " + cursor.getString(2));
                }
                cursor.close();
                db.close();
                break;
            case R.id.btn_add: //添加数据
                name = mEtName.getText().toString();
                phone = mEtPhone.getText().toString();
                db = myHelper.getWritableDatabase();//获取可读写SQLiteDatabse对象
                values = new ContentValues();        //创建ContentValues对象
                values.put("name", name);             //将数据添加到ContentValues对象
                values.put("phone", phone);
                db.insert("information", null, values);
                Toast.makeText(this, "信息已添加", Toast.LENGTH_SHORT).show();
                db.close();
                break;
            case R.id.btn_update: //修改数据
                db = myHelper.getWritableDatabase();
                values = new ContentValues();       // 要修改的数据
                values.put("phone", phone = mEtPhone.getText().toString());
                db.update("information", values, "name=?",
                        new String[]{mEtName.getText().toString()}); // 更新并得到行数
                Toast.makeText(this, "信息已修改", Toast.LENGTH_SHORT).show();
                db.close();
                break;
            case R.id.btn_delete: //删除数据
                db = myHelper.getWritableDatabase();
                db.delete("information", null, null);
                Toast.makeText(this, "信息已删除", Toast.LENGTH_SHORT).show();
                mTvShow.setText("");
                db.close();
                break;
        }
    }