如何访问我的 firebase 数据库中的子项并根据所选的列表视图项在活动中显示它们

Question

我有我的应用程序，我需要显示有关在列表视图中单击的项目的信息。然而，这是存储在我的 firebase 数据库中的数据。数据库如下所示：

现在我想单击列表视图项，以便我可以在不同的活动中显示与其对应的信息。

存储listview和Firebase的MainActivity的代码是：

 public class MainActivity extends AppCompatActivity
    implements NavigationView.OnNavigationItemSelectedListener {


DrawerLayout drawer;
ActionBarDrawerToggle toggle;
private FirebaseDatabase mFirebaseDatabase;
private DatabaseReference mDatabaseReference;
private ChildEventListener mChildEventListener;
private FirebaseAuth mFirebaseAuth;
private FirebaseAuth.AuthStateListener mAuthStateListener;
public TicketAdapter adapter;
private final static  int RC_SIGN_IN = 2;
public String mUsername;
public static String ComplaintID;
public static String StatusImg;
public static String TicketCat;
public static String SubCat;
private static final String TAG = "MainActivity";


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);


    mFirebaseAuth = FirebaseAuth.getInstance();
    mFirebaseDatabase = FirebaseDatabase.getInstance();
    mDatabaseReference = mFirebaseDatabase.getReference().child("Ticket");

    mAuthStateListener = new FirebaseAuth.AuthStateListener() {
        @Override
        public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {
            FirebaseUser user = mFirebaseAuth.getCurrentUser();
            if (user != null) {
                onSignedInInitialized(user.getDisplayName());
            } else {
                onSignedOutCleanup();
                startActivityForResult(
                        getInstance()
                                .createSignInIntentBuilder()
                                .setIsSmartLockEnabled(false)
                                .setAvailableProviders(Arrays.asList(
                                        new AuthUI.IdpConfig.EmailBuilder().build(),
                                        new AuthUI.IdpConfig.GoogleBuilder().build()))
                                .build(),
                        RC_SIGN_IN);
            }
        }
    };

    final ListView listView = (ListView)findViewById(R.id.lvTicket);
    final ArrayList<Ticket> arrayOfTicket = new ArrayList<>();
    adapter = new TicketAdapter(this, arrayOfTicket);
    listView.setAdapter(adapter);

    mDatabaseReference.addChildEventListener(new ChildEventListener() {
        @Override
        public void onChildAdded(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {

            Ticket ticket = (Ticket)dataSnapshot.getValue(Ticket.class);
            adapter.add(ticket);
            adapter.notifyDataSetChanged();
            assert ticket != null;

        }

        @Override
        public void onChildChanged(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {

        }

        @Override
        public void onChildRemoved(@NonNull DataSnapshot dataSnapshot) {

        }

        @Override
        public void onChildMoved(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {

        }

        @Override
        public void onCancelled(@NonNull DatabaseError databaseError) {

        }
    });
    mDatabaseReference = FirebaseDatabase.getInstance().getReference();
    final DatabaseReference TicketCategory = mDatabaseReference.child("Ticket").child("ticketCategory");

    TicketCategory.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            String TCategory = dataSnapshot.child("ticketCategory").getValue(String.class);
            TicketCat = TCategory;
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });

    listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
            Ticket ticket = new Ticket();

            Intent intent = new Intent(view.getContext(), ComplaintDetail.class);

            startActivity(intent);
        }


    });

    final Button button = (Button) findViewById(R.id.complaintbutton);
    button.setOnClickListener(new View.OnClickListener() {
                                  public void onClick(View view) {
                                      Intent intent = new Intent(MainActivity.this, TicketCategory.class);
                                      startActivity(intent);
                                  }
                              }
    );

}

@Override
protected void onPostCreate(Bundle savedInstanceState)
{
    super.onPostCreate(savedInstanceState);
    toggle.syncState();
}

@Override
public void onBackPressed() {
    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    if (drawer.isDrawerOpen(GravityCompat.START)) {
        drawer.closeDrawer(GravityCompat.START);
    } else {
        super.onBackPressed();
    }
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    switch(item.getItemId())
    {
        case R.id.action_settings:
        {
            AuthUI.getInstance().signOut(this);
            return true;
        }
        default:
            return super.onOptionsItemSelected(item);
    }
}

private void detachDatabaseReadListener()
{
    if(mChildEventListener != null)
    {
        mDatabaseReference.removeEventListener(mChildEventListener);
        mChildEventListener = null;
    }
}

@Override
protected void onResume()
{
    super.onResume();
    mFirebaseAuth.addAuthStateListener(mAuthStateListener);
}

@Override
protected void onPause()
{
    super.onPause();
    mFirebaseAuth.removeAuthStateListener(mAuthStateListener);
}

private void onSignedInInitialized(String username)
{
    mUsername = username;
   // attachDatabaseReadListener();
}

private void onSignedOutCleanup()
{
    mUsername = null;

}

这是我要显示孩子的活动的代码：

 public class ComplaintDetail extends AppCompatActivity {

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

    TextView tvComplaintID = (TextView)findViewById(R.id.complaintid);
    TextView tvTicketCat = (TextView)findViewById(R.id.TicketHeading);
    TextView tvSubCat = (TextView)findViewById(R.id.Subheading);

    //tvComplaintID.setText(MainActivity.StatusImg);
     tvTicketCat.setText( MainActivity.TicketCat);
  // tvSubCat.setText(MainActivity.SubCat);


    final Button butt = findViewById(R.id.review);
    butt.setOnClickListener(new View.OnClickListener() {
        public void onClick(View view) {
            Intent intent = new Intent(ComplaintDetail.this, Review.class);
            startActivity(intent);
        }
    });

    final Button button = findViewById(R.id.close);
    button.setOnClickListener(new View.OnClickListener() {
        public void onClick(View view) {
            Toast.makeText(ComplaintDetail.this, "This ticket is closed!!", Toast.LENGTH_SHORT).show();
        }
    });

}}

我想显示孩子：ticketCategory、子类别和状态。 我将非常感谢任何帮助。 谢谢！！

[编辑]

 public class Ticket {
String ticketCategory;
String name;
String complaintID;
String subcategory;
String priority;
String status;
private String comments;
private String cannedReply;

public Ticket(){}


public Ticket (String ticketCategory, String subcategory, String priority, String status, String comments, String cannedReply)
{
    this.ticketCategory = ticketCategory;
 //   this.Name = Name;
    this.subcategory = subcategory;
    this.priority = priority;
    this.status = status;
    this.comments = comments;
    this.cannedReply = cannedReply;
}

public void setTicketCategory(String ticketCategory) {
    this.TicketCategory = ticketCategory;
}

public void setName(String name) {
    this.Name = name;
}

public void setSubcategory(String subcategory) {
    this.Subcategory = subcategory;
}

public void setPriority(String priority) {
    this.priority = priority;
}*/

public void setStatus(String status) {
    this.status = status;
}

public String getTicketCategory() {
    return ticketCategory;
}



public String getSubcategory() {
    return subcategory;
}

public String getPriority() {
    return priority;
}

public String getComments() {
    return comments;
}

public void setComments(String comments) {
    this.comments = comments;
}

public String getCannedReply() {
    return cannedReply;
}

public void setCannedReply(String cannedReply) {
    this.cannedReply = cannedReply;
}

public String getStatus() {return status;}

public String getComplaintID() {
    return complaintID;
}

public static ArrayList<Ticket> getTicket()
{
    ArrayList<Ticket> tickets = new ArrayList<Ticket>();
    return tickets;
}}

Answer 1

只需将您的票证类设为可序列化并在 bundel 中传递它并在下面的其他活动中解析
首先更改您的 Ticket 类定义，如下所示

public class Ticket implements Serializable {

然后像下面这样更改您的点击代码

listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
                Intent intent = new Intent(view.getContext(), ComplaintDetail.class);
                intent.putExtra("ticket", ticket);
                startActivity(intent);
            }
        });

最后在下面的第二个活动中解析并获取您的对象

Ticket ticket= (Ticket) getIntent().getSerializableExtra("ticket");

Answer 2

   listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {


                Intent intent = new Intent(view.getContext(), ComplaintDetail.class);
                intent.putExtra("ticket", ticket);
                startActivity(intent);
            }
    });

我在意图中提到的对象是您从 fireabse 接收的对象，您需要使对象可解析才能将其发送到另一个活动。因此，请确保使其可解析。 下面是实现parceable接口的模型类：-

public class Ticket implements Parcelable {
    private String ticketCategory;
    private String name;
    private String complaintID;
    private String subcategory;
    private String priority;
    private String status;
    private String comments;
    private String cannedReply;

    public Ticket() {
    }


    public Ticket(String ticketCategory, String subcategory, String priority, String status, String comments, String cannedReply) {
        this.ticketCategory = ticketCategory;
        //   this.Name = Name;
        this.subcategory = subcategory;
        this.priority = priority;
        this.status = status;
        this.comments = comments;
        this.cannedReply = cannedReply;
    }

    public String getTicketCategory() {
        return ticketCategory;
    }

    public void setTicketCategory(String ticketCategory) {
        this.ticketCategory = ticketCategory;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getComplaintID() {
        return complaintID;
    }

    public void setComplaintID(String complaintID) {
        this.complaintID = complaintID;
    }

    public String getSubcategory() {
        return subcategory;
    }

    public void setSubcategory(String subcategory) {
        this.subcategory = subcategory;
    }

    public String getPriority() {
        return priority;
    }

    public void setPriority(String priority) {
        this.priority = priority;
    }

    public String getStatus() {
        return status;
    }

    public void setStatus(String status) {
        this.status = status;
    }

    public String getComments() {
        return comments;
    }

    public void setComments(String comments) {
        this.comments = comments;
    }

    public String getCannedReply() {
        return cannedReply;
    }

    public void setCannedReply(String cannedReply) {
        this.cannedReply = cannedReply;
    }

    @Override
    public int describeContents() {
        return 0;
    }

    @Override
    public void writeToParcel(Parcel dest, int flags) {
        dest.writeString(this.ticketCategory);
        dest.writeString(this.name);
        dest.writeString(this.complaintID);
        dest.writeString(this.subcategory);
        dest.writeString(this.priority);
        dest.writeString(this.status);
        dest.writeString(this.comments);
        dest.writeString(this.cannedReply);
    }

    protected Ticket(Parcel in) {
        this.ticketCategory = in.readString();
        this.name = in.readString();
        this.complaintID = in.readString();
        this.subcategory = in.readString();
        this.priority = in.readString();
        this.status = in.readString();
        this.comments = in.readString();
        this.cannedReply = in.readString();
    }

    public static final Parcelable.Creator<Ticket> CREATOR = new Parcelable.Creator<Ticket>() {
        @Override
        public Ticket createFromParcel(Parcel source) {
            return new Ticket(source);
        }

        @Override
        public Ticket[] newArray(int size) {
            return new Ticket[size];
        }
    };
}

所以，我有 set 和 get 方法并实现了 parceable 即使类 parceable 以便您可以发送整个对象。现在在您将接收的其他活动中，您可以使用如下 get 方法

首先通过onCreate中的getIntent()获取intent，并声明对象Ticket。

 ticket = getIntent().getParcelableExtra("Ticket");

如果您需要该对象，您可以直接访问它，如下所示

ticket.getSubcategory();
    ticket.getTicketCategory();
    ticket.getStatus();

所以，那就是问我你是否没有得到任何东西以及它是否不起作用。