如何将多项选择与房间数据库一起使用

Question

如何将交易链接到会员，例如将交易ID链接到多个会员ID？

我有一个创建新交易的活动，在该活动中我输入交易的名称并有一个按钮要插入。单击该按钮后，我想查看成员列表。

然后，我想选择要链接到交易的成员。通过单击每个成员，它应该在我选择的成员旁边显示一个勾号或内容，或者它应该将点击的成员设置为不同的颜色。

然后应该插入我选择的所有链接成员的事务。

我现在这样做了，我只是进行一个新交易，单击它，使用所选交易启动一个新活动，然后在工具栏中单击一个按钮以启动另一个活动，我应该能够选择我想要与交易链接的成员。

是否可以选择我想通过新交易活动直接链接到交易的成员？或者是否可以进行新事务，当我单击按钮保存新事务时，它会将记录插入数据库，并在插入后立即开始我选择要链接到事务的成员的活动？

同样关于我的删除方法：我以 onSwipe 方法实现了该方法。我该怎么做才能点击多个交易，它们有一个勾号或不同的颜色，并同时删除它们？

我可以单击一个按钮(例如在工具栏中(进行删除，然后选择多个成员，单击"确认删除"按钮，显示确认屏幕(但尚未删除(，接受确认屏幕后，删除它们？

类交易：

@Entity(tableName = "transaction_table")
public class Transaction {
@PrimaryKey(autoGenerate = true)
@ColumnInfo(name = "TransactionID")
private long id;
@ColumnInfo(name = "Transaction Name")
private String transactionName;
@ColumnInfo(name = "Transaction Balance")
private double balance;
public double getBalance() {
return balance;
}
public void setBalance(double balance) {
this.balance = balance;
}
public long getId() {
return id;
}
public void setId(long id) {
this.id = id;
}
public String getTransactionName() {
return transactionName;
}
public void setTransactionName(String transactionName) {
this.transactionName = transactionName;
}
public Transaction(String transactionName, double balance) {
this.transactionName = transactionName;
this.balance = balance;
}
}

班级成员：

@Entity(tableName = "member_table")
public class Member {

@PrimaryKey(autoGenerate = true)
@ColumnInfo(name = "MemberID")
private long id;
@ColumnInfo(name = "First Name")
private String firstname;
@ColumnInfo(name = "Surname")
private String surname;
@ColumnInfo(name = "Balance")
private double balance;
public String getFirstname() {
return firstname;
}
public void setFirstname(String firstname) {
this.firstname = firstname;
}
public String getSurname() {
return surname;
}
public void setSurname(String surname) {
this.surname = surname;
}
public double getBalance() {
return balance;
}
public void setBalance(double balance) {
this.balance = balance;
}
public long getId() {
return id;
}
public void setId(long id) {
this.id = id;
}
public Member(String firstname, String surname) {
this.firstname = firstname;
this.surname = surname;
this.balance = 0;
}
}

类交易主要活动：

public class TransactionMainActivity extends AppCompatActivity implements TransactionListAdapter.TransactionClickListener {
private TransactionViewModel mTransactionViewModel;
private List<Transaction> mTransaction;
public static final int NEW_TRANSACTION_ACTIVITY_REQUEST_CODE = 1;
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.transaction_activity);
Toolbar toolbar = findViewById(R.id.toolbar_TransactionMainActivity);
setSupportActionBar(toolbar);
if (getSupportActionBar() != null) {
getSupportActionBar().setTitle(R.string.Transaction);
}
FloatingActionButton fab = findViewById(R.id.fab_TransactionMainActivity);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent intent = new Intent(TransactionMainActivity.this, NewTransactionActivity.class);
startActivityForResult(intent, NEW_TRANSACTION_ACTIVITY_REQUEST_CODE);
}
});
RecyclerView recyclerView = findViewById(R.id.RecyclerViewCard_Transaction);
final TransactionListAdapter adapter = new TransactionListAdapter(this);
recyclerView.setAdapter(adapter);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
mTransactionViewModel = ViewModelProviders.of(this).get(TransactionViewModel.class);
mTransactionViewModel.getAllTransactions().observe(this, new Observer<List<Transaction>>() {
@Override
public void onChanged(@Nullable List<Transaction> transactions) {
mTransaction = transactions;
adapter.setTransaction(transactions);
}
});
ItemTouchHelper helper = new ItemTouchHelper(
new ItemTouchHelper.SimpleCallback(0,
ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT) {
@Override
public boolean onMove(RecyclerView recyclerView,
RecyclerView.ViewHolder viewHolder,
RecyclerView.ViewHolder target) {
return false;
}
@Override
public void onSwiped(RecyclerView.ViewHolder viewHolder, int direction) {
int position = viewHolder.getAdapterPosition();
Transaction myTransaction = adapter.getTransactionAtPosition(position);
Toast.makeText(TransactionMainActivity.this,
getString(R.string.TransactionDeleted) + " " +
myTransaction.getTransactionName(), Toast.LENGTH_LONG).show();
mTransactionViewModel.delete(myTransaction);
}
});
helper.attachToRecyclerView(recyclerView);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.MainMenuToolbarSearch:
case R.id.MainMenuToolbarAdd:
case R.id.MainMenuToolbarDelete:
}
return super.onOptionsItemSelected(item);
}
public void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == NEW_TRANSACTION_ACTIVITY_REQUEST_CODE && resultCode == RESULT_OK) {
Transaction transaction = new Transaction(data.getStringExtra(NewTransactionActivity.EXTRA_REPLY), data.getDoubleExtra(NewTransactionActivity.EXTRA_REPLY2, -1));
mTransactionViewModel.insert(transaction);
} else
{
Toast.makeText(
getApplicationContext(),
R.string.transaction_not_saved,
Toast.LENGTH_LONG).show();
}
}

类新事务活动：

public class NewTransactionActivity extends AppCompatActivity {
public static final String EXTRA_REPLY = "com.example.android.transactionlistsql.REPLY";
public static final String EXTRA_REPLY2 = "com.example.android.transactionlistsql.REPLY2";
private EditText mEditTextTransaction;
private EditText mEditTextTransaction2;

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.newtransaction_activity);
mEditTextTransaction = findViewById(R.id.NewTransactionName);
mEditTextTransaction2 = findViewById(R.id.NewTransactionBalance);
mEditTextTransaction2.setInputType(InputType.TYPE_CLASS_NUMBER | InputType.TYPE_NUMBER_FLAG_DECIMAL);
mEditTextTransaction2.setText("0");
final Button button = findViewById(R.id.NewTransactionButtonSave);
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent replyIntent = new Intent();
if (TextUtils.isEmpty(mEditTextTransaction.getText())){
Toast.makeText(getApplicationContext(), R.string.TransactionNameMissing, Toast.LENGTH_LONG).show();
return;
}
else if (TextUtils.isEmpty(mEditTextTransaction2.getText())){
mEditTextTransaction2.setText("0");
}
else {                 
String newtransactionname = mEditTextTransaction.getText().toString();
double newtransactionbalance = (Double.parseDouble(mEditTextTransaction2.getText().toString()));
replyIntent.putExtra(EXTRA_REPLY, newtransactionname);
replyIntent.putExtra(EXTRA_REPLY2, newtransactionbalance);
setResult(RESULT_OK, replyIntent);
}
finish();
}
});
}
}

我的插入方法的异步任务：

private static class insertAsyncTask extends AsyncTask<Transaction, Void, Void> {
private TransactionDao mAsyncTaskDao;
insertAsyncTask(TransactionDao dao) {
mAsyncTaskDao = dao;
}
@Override
protected Void doInBackground(final Transaction... params) {
mAsyncTaskDao.insert(params[0]);
return null;
}
}

标记为错误的行是这样的：mAsyncTaskDao.insert(params[0](;

错误：

07-11 03:10:49.003 16307-16508/com.example.mainbuchhaltung E/AndroidRuntime: FATAL EXCEPTION: AsyncTask #4
Process: com.example.mainbuchhaltung, PID: 16307
java.lang.RuntimeException: An error occurred while executing doInBackground()
at android.os.AsyncTask$3.done(AsyncTask.java:309)
at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:354)
at java.util.concurrent.FutureTask.setException(FutureTask.java:223)
at java.util.concurrent.FutureTask.run(FutureTask.java:242)
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:234)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1113)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588)
at java.lang.Thread.run(Thread.java:818)
Caused by: android.database.sqlite.SQLiteConstraintException: FOREIGN KEY constraint failed (code 787)
#################################################################
Error Code : 787 (SQLITE_CONSTRAINT_FOEIGNKEY)
Caused By : Abort due to constraint violation.
(FOREIGN KEY constraint failed (code 787))
#################################################################
at android.database.sqlite.SQLiteConnection.nativeExecuteForLastInsertedRowId(Native Method)
at android.database.sqlite.SQLiteConnection.executeForLastInsertedRowId(SQLiteConnection.java:915)
at android.database.sqlite.SQLiteSession.executeForLastInsertedRowId(SQLiteSession.java:788)
at android.database.sqlite.SQLiteStatement.executeInsert(SQLiteStatement.java:86)
at android.arch.persistence.db.framework.FrameworkSQLiteStatement.executeInsert(FrameworkSQLiteStatement.java:50)
at android.arch.persistence.room.EntityInsertionAdapter.insert(EntityInsertionAdapter.java:64)
at com.example.mainbuchhaltung.Transaction.TransactionDao_Impl.insert(TransactionDao_Impl.java:96)
at com.example.mainbuchhaltung.Transaction.TransactionRepository$insertAsyncTask.doInBackground(TransactionRepository.java:64)
at com.example.mainbuchhaltung.Transaction.TransactionRepository$insertAsyncTask.doInBackground(TransactionRepository.java:54)
at android.os.AsyncTask$2.call(AsyncTask.java:295)
at java.util.concurrent.FutureTask.run(FutureTask.java:237)
... 4 more

Answer 1

在事务和成员实体之间创建关系，如下所示

然后，一旦获得交易数据(交易名称和金额(，则必须将数据传递给MemberList活动，如下所示

现在，在您的成员列表屏幕中，一旦完成您的选择，请按照以下过程操作：
假设您在字符串中有成员ID。

String memberIds = "12,18,25,27,30";

现在，您必须创建将所有成员 ID 分开的事务实体对象，并将其插入事务表中，如下所示。

String[] memberArray = memberIds.split(",", memberIds.length());
for(String memberId : memberArray){
// transactionName & transactionAmount which you received in the bundle from add transaction activity
Transaction objTransaction = new Transaction(transactionName, transactionAmount); 
objTransaction.setMemberId(Long.parseLong(memberId));
// Insert data into your database
mTransactionViewModel.insert(objTransaction);
}

它将为"transaction_table"表中的每个成员 ID 创建一个具有一对一关系的单独条目。

您可以通过执行此处提到的查询来获取交易数据