在一个片段内点击按钮改变一个片段。

Question

我试图改变一个片段，当一个按钮被点击在该片段上时。当这样做的时候，片段改变了，但按钮仍然出现在改变后的片段上。我是开发新手，谁能帮我解决这个问题。

HomeFragment.java

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

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;
import androidx.fragment.app.FragmentManager;
import androidx.fragment.app.FragmentTransaction;
import androidx.lifecycle.Observer;
import androidx.lifecycle.ViewModelProviders;

import com.vinodsharma.hcms_attendance_app.R;
import com.vinodsharma.hcms_attendance_app.databinding.FragmentHomeBinding;
import com.vinodsharma.hcms_attendance_app.fragments.NewFragment;

public class HomeFragment extends Fragment {

    private HomeViewModel homeViewModel;

    FragmentHomeBinding binding;

    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.text_home);
//        homeViewModel.getText().observe(getViewLifecycleOwner(), new Observer<String>() {
//            @Override
//            public void onChanged(@Nullable String s) {
//                textView.setText(s);
//            }
//        });
//        return root;

        binding=FragmentHomeBinding.inflate(getLayoutInflater());
        return binding.getRoot();
    }

    @Override
    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);

        binding.btnAttendance.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Fragment NewFragment=new NewFragment();
                FragmentManager manager=getActivity().getSupportFragmentManager();
                FragmentTransaction fragmentTransaction= manager.beginTransaction();
                fragmentTransaction.replace(R.id.nav_host_fragment,NewFragment);
                fragmentTransaction.addToBackStack(null);
                fragmentTransaction.commit();
            }
        });

    }

    //*****To avoid memory leaks****8
    @Override
    public void onDestroyView() {
        super.onDestroyView();
        binding=null;
    }
}

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"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".ui.home.HomeFragment">

    <Button
        android:id="@+id/btn_goto_new"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:layout_marginEnd="8dp"
        android:background="#00f"
        android:gravity="center"
        android:textColor="#ffff"
        android:textSize="20sp"
        android:text="Go To New Fragment"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>

NewFragment.java

public class NewFragment extends Fragment {
    public NewFragment() {
        // Required empty public constructor
    }


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_new, container, false);
    }
}

fragment_new.xml

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".fragments.NewFragment"
    >

    <!-- TODO: Update blank fragment layout -->
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/hello_blank_fragment"
        android:layout_gravity="center"
        android:textColor="#ffff"
        android:textSize="24sp"/>

</FrameLayout>

内容_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"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:showIn="@layout/app_bar_main">

    <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_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:navGraph="@navigation/mobile_navigation" />
</androidx.constraintlayout.widget.ConstraintLayout>

Answer 1

你使用的是navHostFragment。文档。https:/developer.android.comguidenavigationnavigation-getting-started。

你应该在导航图中创建动作，并做类似的事情。

public void onClick(View v) {
 findNavController().navigate(R.id.action...)
}