尝试在Android Room中捕获SQLiteConstraintException并显示警报

import android.os.Bundle;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;
import androidx.room.Room;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class MainActivity extends AppCompatActivity {

    private AppDatabase db;
    private ExecutorService executorService;

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

        db = Room.databaseBuilder(getApplicationContext(),
                AppDatabase.class, "database-name").build();
        executorService = Executors.newSingleThreadExecutor();

        // 假设我们有一个User实体和一个UserDao
        User newUser = new User("John Doe", "johndoe@example.com");
        insertUser(newUser);
    }

    private void insertUser(final User user) {
        executorService.execute(new Runnable() {
            @Override
            public void run() {
                try {
                    // 尝试插入用户
                    db.userDao().insert(user);
                } catch (SQLiteConstraintException e) {
                    // 捕获异常并在UI线程显示警报
                    runOnUiThread(new Runnable() {
                        @Override
                        public void run() {
                            Toast.makeText(MainActivity.this,
                                    "Error: User already exists!", Toast.LENGTH_LONG).show();
                        }
                    });
                }
            }
        });
    }
}