lihua作业绿豆通讯录.zip

public class MainActivity extends AppCompatActivity implements View.OnClickListener { MyHelper myHelper; private EditText mEtName; private EditText mEtPhone; private TextView mTvShow; private Button mBtnAdd, mBtnQuery, mBtnUpdate, mBtnDelete; @Override protected void onCreate(@Nullable Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); myHelper = new MyHelper(this); init(); } private void init(){ mEtName=findViewById(R.id.et_name); mEtPhone=findViewById(R.id.et_phone); mTvShow=findViewById(R.id.tv_show); mBtnAdd=findViewById(R.id.btn_add); mBtnQuery=findViewById(R.id.btn_query); mBtnUpdate=findViewById(R.id.btn_update); mBtnDelete=findViewById(R.id.btn_delete); mBtnAdd.setOnClickListener(this); mBtnQuery.setOnClickListener(this); mBtnUpdate.setOnClickListener(this); mBtnDelete.setOnClickListener(this); } @Override public void onClick(View view) { String name,phone; SQLiteDatabase db; ContentValues values; switch (view.getId()) { case R.id.btn_add: name = mEtName.getText().toString(); phone = mEtPhone.getText().toString(); db = myHelper.getWritableDatabase(); values = new ContentValues(); values.put("name", name); 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_query: 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_update: db = myHelper.getWritableDatabase(); values = new ContentValues(); values.put("phone", phone = mEtPhone.getText().toString()); db.update("information", values, "name=?", new String[]{mEtName.getText().toString()}); Toast.makeText(this, "信息已修改", Toast.LENGTH_SHORT).show(); db.close(); break; case R.id.btn_delete: 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; } } class MyHelper extends SQLiteOpenHelper{ public MyHelper(Context context){ super(context,"itcast.db",null,1); } @Override public void onCreate(SQLiteDatabase sqLiteDatabase) { sqLiteDatabase.execSQL("CREATE TABLE information(_id INTEGER PRIMARY KEY AUTOINCREMENT, name VARCHAR(20),phone VARCHAR(20))"); } @Override public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) { } } }