我在DB Browser拳击类和第二人中创建了两个表。
类别有两个字段，第一个id和第二个名称，人们有三个字段id，namd和category id。
听到我在类别字段中放了五个项目，很多人使用category_id命名如何显示数据列表视图或者Recyclerview
我在数据库浏览器中有静态添加数据
请帮助我!!
DataBaseHelper.java
public class DataBaseHelper extends SQLiteOpenHelper {
private static String DB_PATH = "/data/data/com.example.mobisharnam.database/databases/";
private static String DB_NAME = "alertme";
private SQLiteDatabase myDataBase;
private final Context myContext;
public DataBaseHelper(Context context) {
super(context, DB_NAME, null, 1);
this.myContext = context;
}
public void createDataBase() throws IOException {
boolean dbExist = checkDataBase();
if (dbExist) {
} else {
this.getReadableDatabase();
try {
copyDataBase();
} catch (IOException e) {
throw new Error("Error copying database");
}
}
}
private boolean checkDataBase() {
SQLiteDatabase checkDB = null;
try {
String myPath = DB_PATH + DB_NAME;
checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
} catch (SQLiteException e) {
}
if (checkDB != null) {
checkDB.close();
}
return checkDB != null ? true : false;
}
private void copyDataBase() throws IOException {
InputStream myInput = myContext.getAssets().open(DB_NAME);
String outFileName = DB_PATH + DB_NAME;
OutputStream myOutput = new FileOutputStream(outFileName);
byte[] buffer = new byte[1024];
int length;
while ((length = myInput.read(buffer)) > 0) {
myOutput.write(buffer, 0, length);
}
myOutput.flush();
myOutput.close();
myInput.close();
}
public void openDataBase() throws SQLException {
String myPath = DB_PATH + DB_NAME;
myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
}
@Override
public synchronized void close() {
if (myDataBase != null)
myDataBase.close();
super.close();
}
@Override
public void onCreate(SQLiteDatabase db) {
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
}
Activity.class
公共类MainActivity扩展了AppCompatActivity {
private static DataBaseHelper mDbHelper;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mDbHelper = new DataBaseHelper(this);
try {
mDbHelper.createDataBase();
} catch (IOException ioe) {
throw new Error("Unable to create database");
}
try {
mDbHelper.openDataBase();
} catch (SQLException sqle) {
throw sqle;
}
}
}
人物模型
public class People {
private String PeopleName;
private int PeopleId;
public People(String peopleName,int peopleId) {
this.PeopleId = peopleId;
this.PeopleName = peopleName;
}
public String getPeopleName() {
return PeopleName;
}
public void setPeopleName(String peopleName) {
PeopleName = peopleName;
}
public int getPeopleId() {
return PeopleId;
}
public void setPeopleId(int peopleId) {
PeopleId = peopleId;
}
}
类别模型
public class Category {
int CategoryId;
String CategoryName;
public Category(int categoryId,String categoryName){
this.CategoryId = categoryId;
this.CategoryName = categoryName;
}
public int getCategoryId() {
return CategoryId;
}
public void setCategoryId(int categoryId) {
CategoryId = categoryId;
}
public String getCategoryName() {
return CategoryName;
}
public void setCategoryName(String categoryName) {
CategoryName = categoryName;
}
}