0
StudentInformation Javaクラス内の特定のデータベース子とディスプレイを取得します。
public class StudentInformation {
String name;
String ID;
String studentID;
String email;
String phone_num;
public StudentInformation() {
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getID() {
return ID;
}
public void setID(String ID) {
this.ID = ID;
}
public String getStudentID() {
return studentID;
}
public void setStudentID(String studentID) {
this.studentID = studentID;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
public String getPhone_num() {
return phone_num;
}
public void setPhone_num(String phone_num) {
this.phone_num = phone_num;
}
}
私は方法の多くを試してみたが、ListViewコントロールは、まだ何も表示しないとアプリが突然停止しました。
public class StudentInfoActivity extends AppCompatActivity {
//add Firebase Database stuff
private FirebaseDatabase mFirebaseDatabase;
private FirebaseAuth mAuth;
private FirebaseAuth.AuthStateListener mAuthListener;
private DatabaseReference myRef;
private String userID;
ListView mListView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_student_info);
mListView = (ListView) findViewById(R.id.listview);
//declare the database reference object. This is what we use to access the database.
//NOTE: Unless you are signed in, this will not be useable.
mAuth = FirebaseAuth.getInstance();
mFirebaseDatabase = FirebaseDatabase.getInstance();
myRef = mFirebaseDatabase.getReference();
FirebaseUser user = mAuth.getCurrentUser();
userID = user.getUid();
mAuthListener = new FirebaseAuth.AuthStateListener() {
@Override
public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {
FirebaseUser user = firebaseAuth.getCurrentUser();
if (user != null) {
// User is signed in
toastMessage("User Information");
} else {}
// ...
}
}; //end authlistener
myRef.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
// This method is called once with the initial value and again
// whenever data at this location is updated.
showData(dataSnapshot);
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
} // end oncreate
private void showData(DataSnapshot dataSnapshot) {
for(DataSnapshot ds : dataSnapshot.getChildren()){
StudentInformation sInfo = new StudentInformation();
sInfo.setName(ds.child(userID).child("userInfo").getValue(StudentInformation.class).getName());
sInfo.setID(ds.child(userID).child("userInfo").getValue(StudentInformation.class).getID());
sInfo.setStudentID(ds.child(userID).child("userInfo").getValue(StudentInformation.class).getStudentID());
sInfo.setEmail(ds.child(userID).child("userInfo").getValue(StudentInformation.class).getEmail());
sInfo.setPhone_num(ds.child(userID).child("userInfo").getValue(StudentInformation.class).getPhone_num());
ArrayList<String> array = new ArrayList<>();
array.add(sInfo.getName());
array.add(sInfo.getID());
array.add(sInfo.getStudentID());
array.add(sInfo.getEmail());
array.add(sInfo.getPhone_num());
ArrayAdapter adapter = new ArrayAdapter(this,android.R.layout.simple_list_item_1,array);
mListView.setAdapter(adapter);
}
} //end showdata
@Override
public void onStart() {
super.onStart();
mAuth.addAuthStateListener(mAuthListener);
}
@Override
public void onStop() {
super.onStop();
if (mAuthListener != null) {
mAuth.removeAuthStateListener(mAuthListener);
}
}
private void toastMessage(String message){
Toast.makeText(this,message,Toast.LENGTH_SHORT).show();
}
} // end class
これはコードを使用しています。私はgetchildrenメソッドについて疑問に思っていましたが、私はコードで何か間違ったことをしましたか？誰もこれで私を助けることができますか？
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference userInfoRef = rootRef.child("users").child(userID).child("userInfo");
ValueEventListener eventListener = new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
String ID = ds.child("ID").getValue(String.class);
String email = ds.child("email").getValue(String.class);
String name = ds.child("name").getValue(String.class);
String phone_num = ds.child("phone_num").getValue(String.class);
String studentID = ds.child("studentID").getValue(String.class);
Log.d("TAG", ID + "/" + email + "/" + name + "/" + phone_num + "/" + studentID);
}
@Override
public void onCancelled(DatabaseError databaseError) {}
};
userInfoRef.addListenerForSingleValueEvent(eventListener);