java - Android Studio 中的 Fragment 不稳定

Question

我是使用 Android Studio 的完全初学者。在此代码中，我尝试使用工具栏中强加的按钮来实现 fragment 。基本上，我想在单击添加按钮时显示 fragment 内容。我想从 fragment 中获取用户的一些输入，将其更新为Firebase 并从 Firebase 接收它并将其检索到回收者 View 。当我尝试执行下面给出的代码时， fragment 闪烁，然后应用程序停止工作。任何应用我的流程的替代方案将不胜感激。

这是我的 Activity 文件..

package com.example.myapplication;

import androidx.annotation.NonNull;
import androidx.appcompat.app.ActionBar;
import androidx.appcompat.app.AppCompatActivity;
import androidx.appcompat.widget.Toolbar;
import androidx.fragment.app.Fragment;
import androidx.fragment.app.FragmentTransaction;

import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.widget.EditText;
import android.widget.FrameLayout;
import android.widget.Toast;


public class history extends AppCompatActivity {



    enter code here

    EditText success;
    private FrameLayout frameLayout;
    private historyfrag historyfrag;

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


        Toolbar toolbar = findViewById(R.id.toolbarhistory);
        setSupportActionBar(toolbar);


        ActionBar ab =getSupportActionBar();
        ab.setDisplayHomeAsUpEnabled(true);

        frameLayout = findViewById(R.id.framelayut);

        historyfrag = new historyfrag();

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.toolbarhistorymenu,menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(@NonNull MenuItem item){
            switch (item.getItemId()) {

                case R.id.print:
                    Toast.makeText(getApplicationContext(), "Print", Toast.LENGTH_LONG).show();
                    return true;

                case R.id.add:
                    setupfragment(historyfrag);
                    return true;

                default:
                    return super.onOptionsItemSelected(item);


            }



    }

    private void setupfragment(Fragment fragment) {

        FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
        fragmentTransaction.replace(R.id.framelayut,fragment);
        fragmentTransaction.commit();


    }


}

这是 Activity 的 xml 文件...

<RelativeLayout 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">


    <androidx.appcompat.widget.Toolbar
        android:id="@+id/toolbarhistory"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:background="@color/colorAccent"
        android:elevation="6dp"
        app:menu="@menu/toolbarhistorymenu"
        android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
        app:title="History" />

    <FrameLayout
        android:id="@+id/framelayut"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_below="@id/toolbarhistory" />

</RelativeLayout>

在Logcat中发现这个错误

    java.lang.RuntimeException: com.example.myapplication.history@2fb40c4 must implement OnFragmentInteractionListener
        at com.example.myapplication.historyfrag.onAttach(historyfrag.java:85)
        at androidx.fragment.app.Fragment.performAttach(Fragment.java:2574)
        at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManagerImpl.java:828)
        at androidx.fragment.app.FragmentTransition.addToFirstInLastOut(FragmentTransition.java:1197)
        at androidx.fragment.app.FragmentTransition.calculateFragments(FragmentTransition.java:1080)
        at androidx.fragment.app.FragmentTransition.startTransitions(FragmentTransition.java:119)
        at androidx.fragment.app.FragmentManagerImpl.executeOpsTogether(FragmentManagerImpl.java:1866)
        at androidx.fragment.app.FragmentManagerImpl.removeRedundantOperationsAndExecute(FragmentManagerImpl.java:1824)
        at androidx.fragment.app.FragmentManagerImpl.execPendingActions(FragmentManagerImpl.java:1727)
        at androidx.fragment.app.FragmentManagerImpl$2.run(FragmentManagerImpl.java:150)
        at android.os.Handler.handleCallback(Handler.java:883)
        at android.os.Handler.dispatchMessage(Handler.java:100)
        at android.os.Looper.loop(Looper.java:214)
        at android.app.ActivityThread.main(ActivityThread.java:7356)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)

Answer 1

将类名称更改为:

public class history extends AppCompatActivity implements YourFragmentClassName.OnFragmentInteractionListener

在 fragment 类中你应该有:

public interface OnFragmentInteractionListener {
    // TODO: Update argument type and name
    void onFragmentInteraction(Uri uri);
}