如何摆脱出现在我的 Android 应用顶部的额外间距？

Question

我正在为我的一门大学课程构建一个 Android 应用的主页。我的小组正在使用 Android Studio。我有我原来的布局，但我在上面写着欢迎的地方有这个随机的额外空间。

我无法弄清楚如何摆脱顶部的随机间距，它会将我的其余对象向下推（报告列表消失在导航栏下方）

这是我的 fragment_home.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <EditText
        android:id="@+id/editText"
        android:layout_width="365dp"
        android:layout_height="wrap_content"
        android:text="@string/home_welcome"
        android:textAlignment="center"
        android:textSize="20pt"
        app:layout_constraintBottom_toTopOf="@+id/text_appts"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <EditText
        android:id="@+id/text_appts"
        android:layout_width="365dp"
        android:layout_height="55dp"
        android:ems="10"
        android:text="@string/title_appointments"
        android:textSize="14pt"
        app:layout_constraintBottom_toTopOf="@+id/recycler_appts"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/editText" />

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recycler_appts"
        android:layout_width="360dp"
        android:layout_height="125dp"
        app:layout_constraintBottom_toTopOf="@+id/text_chats"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.484"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/text_appts"
        app:layout_constraintVertical_bias="0.226" />

    <EditText
        android:id="@+id/text_chats"
        android:layout_width="365dp"
        android:layout_height="55dp"
        android:ems="10"
        android:text="@string/title_chats"
        android:textSize="14pt"
        app:layout_constraintBottom_toTopOf="@+id/recycler_chats"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/recycler_appts" />

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recycler_chats"
        android:layout_width="360dp"
        android:layout_height="125dp"
        app:layout_constraintBottom_toTopOf="@+id/text_reports"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.484"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/text_chats"
        app:layout_constraintVertical_bias="0.226" />

    <EditText
        android:id="@+id/text_reports"
        android:layout_width="365dp"
        android:layout_height="55dp"
        android:ems="10"
        android:text="@string/title_reports"
        android:textSize="14pt"
        app:layout_constraintBottom_toTopOf="@+id/recycler_reports"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/recycler_chats" />

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recycler_reports"
        android:layout_width="360dp"
        android:layout_height="125dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.424"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/text_reports"
        app:layout_constraintVertical_bias="0.226" />

</androidx.constraintlayout.widget.ConstraintLayout>

这是我的 HomeFragment.java

package com.example.telemedicine.ui.home;

import android.app.Activity;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import androidx.annotation.Nullable;
import androidx.annotation.NonNull;
import androidx.fragment.app.Fragment;
import androidx.lifecycle.Observer;
import androidx.lifecycle.ViewModelProviders;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import com.example.telemedicine.R;
import com.example.telemedicine.ui.utilities.RecyclerItem;

public class HomeFragment extends Fragment {

    private HomeViewModel homeViewModel;
    private RecyclerView recyclerView_appt, recyclerView_chat, recyclerView_report;
    private RecyclerView.Adapter mAdapter_appt, mAdapter_chat, mAdapter_report;
    private RecyclerView.LayoutManager layoutManager_appt, layoutManager_chat, layoutManager_report;
    private String[] apptData = {"Physical - 9/29 @ 10:00am", "Vaccination - 10/4 @ 1:30pm", "Check-Up - 10/19 @ 9:00am"};
    private String[] chatData = {"Dr. Jane Smith", "Dr. Hayden Lee", "Dr. Michael Dean"};
    private String[] reportData = {"Blood Work 9/10", "Vaccination Summary 9/1", "Physical 8/23"};
    //Activity activity = (Activity)getContext();

    public View onCreateView(@NonNull LayoutInflater inflater,
                             ViewGroup container, Bundle savedInstanceState) {
        homeViewModel =
                ViewModelProviders.of(this).get(HomeViewModel.class);
        View root = inflater.inflate(R.layout.fragment_home, container, false);
        final TextView textView = root.findViewById(R.id.editText);
        homeViewModel.getText().observe(this, new Observer<String>() {
            @Override
            public void onChanged(@Nullable String s) {
                textView.setText(s);
            }
        });

        recyclerView_appt = (RecyclerView)root.findViewById(R.id.recycler_appts);
        layoutManager_appt = new LinearLayoutManager(this.getActivity());
        recyclerView_appt.setLayoutManager(layoutManager_appt);
        mAdapter_appt = new RecyclerItem(apptData);
        recyclerView_appt.setAdapter(mAdapter_appt);

        recyclerView_chat = (RecyclerView)root.findViewById(R.id.recycler_chats);
        layoutManager_chat = new LinearLayoutManager(this.getActivity());
        recyclerView_chat.setLayoutManager(layoutManager_chat);
        mAdapter_chat = new RecyclerItem(chatData);
        recyclerView_chat.setAdapter(mAdapter_chat);

        recyclerView_report = (RecyclerView)root.findViewById(R.id.recycler_reports);
        layoutManager_report = new LinearLayoutManager(this.getActivity());
        recyclerView_report.setLayoutManager(layoutManager_report);
        mAdapter_report = new RecyclerItem(reportData);
        recyclerView_report.setAdapter(mAdapter_report);

        return root;
    }
}

这是我的 HomeViewModel.java

package com.example.telemedicine.ui.home;

import androidx.lifecycle.LiveData;
import androidx.lifecycle.MutableLiveData;
import androidx.lifecycle.ViewModel;

public class HomeViewModel extends ViewModel {

    private MutableLiveData<String> mText;

    public HomeViewModel() {
        mText = new MutableLiveData<>();
    }

    public LiveData<String> getText() {
        return mText;
    }
}

还有我的activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/container"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/colorBackground"
    android:paddingTop="?attr/actionBarSize">

    <com.google.android.material.bottomnavigation.BottomNavigationView
        android:id="@+id/nav_view"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="0dp"
        android:layout_marginEnd="0dp"
        android:background="?android:attr/windowBackground"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:menu="@menu/bottom_nav_menu" />

    <fragment
        android:id="@+id/nav_host_fragment"
        android:name="androidx.navigation.fragment.NavHostFragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:defaultNavHost="true"
        app:layout_constraintBottom_toTopOf="@id/nav_view"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:navGraph="@navigation/mobile_navigation" />

</androidx.constraintlayout.widget.ConstraintLayout>

我不知道要包括哪些其他文件，但希望问题出在这四个文件中。我已经尝试了很多方法来消除这种间距，但我不知道如何消除它。

提前致谢！！

Answer 1

在您的 activity_main.xml 文件中，尝试删除 ConstraintLayout 中的 android:paddingTop="?attr/actionBarSize" 行，因为没有 actionBar。

Answer 2

在您的activity_main.xml 中将'fragment' (nav_host_fragment) layout_width 和layout_height 更改为0dp。这是使用约束的正确形式。

 <fragment
    android:id="@+id/nav_host_fragment"
    android:name="androidx.navigation.fragment.NavHostFragment"
    android:layout_width="0dp"
    android:layout_height="0dp"
    app:defaultNavHost="true"
    app:layout_constraintBottom_toTopOf="@id/nav_view"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    app:layout_constraintTop_toTopOf="parent"
    app:navGraph="@navigation/mobile_navigation" />