Question

我正在为我的机器人团队创建一个应用程序，以便我们可以快速浏览一些重要的网站。我遇到的问题是我可以使用后退按钮浏览其中一个片段（直到它从应用程序退出），但另一个片段标题为＆＃34; delphiFragment＆＃34;无法向后浏览网站。

如果我能提供任何其他信息，请说明。

这是我的主要活动

package com.thirdspare.android.ckcyberpackapp;

import android.app.Fragment;
import android.app.FragmentTransaction;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.design.widget.BottomNavigationView;
import android.support.v7.app.AppCompatActivity;
import android.view.KeyEvent;
import android.view.MenuItem;
import android.webkit.WebView;
import android.widget.TextView;

import static com.thirdspare.android.ckcyberpackapp.R.id.container;


public class MainActivity extends AppCompatActivity {
    Fragment homeFragment = new HomeFragment();
    Fragment delphiFragment = new DelphiFragment();
    Fragment tbaFragment = new TBAFragment();
    private TextView mTextMessage;
    public static WebView mWebView;


    private BottomNavigationView.OnNavigationItemSelectedListener mOnNavigationItemSelectedListener
            = new BottomNavigationView.OnNavigationItemSelectedListener() {

        @Override
        public boolean onNavigationItemSelected(@NonNull MenuItem item) {
            switch (item.getItemId()) {
                case R.id.navigation_home:
                   mTextMessage.setText(R.string.title_home);
                    getFragmentManager().beginTransaction()
                    .show(homeFragment)
                    .commit();
                    return true;
                case R.id.navigation_delphi:
                   // mTextMessage.setText(R.string.title_delphi);
                    getFragmentManager().beginTransaction()
                            .show(delphiFragment)
                            .hide(homeFragment)
                            .hide(tbaFragment)
                            .commit();

                    return true;
                case R.id.navigation_TBA:
                   mTextMessage.setText(R.string.title_tba);
                    getFragmentManager().beginTransaction()
                            .show(tbaFragment)
                            .hide(homeFragment)
                            .hide(delphiFragment)
                            .commit();
                    return true;
            }
            return false;
        }

    };
    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        // Check if the key event was the Back button and if there's history
        if ((keyCode == KeyEvent.KEYCODE_BACK) && mWebView.canGoBack()) {
            mWebView.goBack();
            return true;
        }
        // If it wasn't the Back key or there's no web page history, bubble up to the default
        // system behavior (probably exit the activity)
        return super.onKeyDown(keyCode, event);
    }

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



        mTextMessage = (TextView) findViewById(R.id.message);
        BottomNavigationView navigation = (BottomNavigationView) findViewById(R.id.navigation);
        navigation.setOnNavigationItemSelectedListener(mOnNavigationItemSelectedListener);

        if (savedInstanceState == null) {
            FragmentTransaction ft = getFragmentManager().beginTransaction();
            ft.add(container, homeFragment);
            ft.add(container, delphiFragment);
            ft.add(container, tbaFragment);
            ft.hide(delphiFragment);
            ft.hide(tbaFragment);
            ft.commit();
        }
    }




}

这是我的delphiFragment类

package com.thirdspare.android.ckcyberpackapp;

import android.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.webkit.WebSettings;
import android.webkit.WebView;
import android.webkit.WebViewClient;

import static com.thirdspare.android.ckcyberpackapp.MainActivity.mWebView;


public class DelphiFragment extends Fragment {
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup parentViewGroup, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.frag_delphi, parentViewGroup, false);
        mWebView = (WebView)view.findViewById(R.id.wbvCD);
        // Enable Javascript
        WebSettings webSettings = mWebView.getSettings();
        webSettings.setJavaScriptEnabled(true);
        mWebView.setWebViewClient(new WebViewClient());
        mWebView.loadUrl("https://www.chiefdelphi.com/forums/portal.php");
        return view;



    }
}

这几乎与其他webview片段相同

Answer 1

在MainActivity中，您正在添加三个片段并隐藏另外两个片段。稍后您要求隐藏和显示片段。基于我的理解，hide将禁用窗口中的片段视图，但它仍然处于其生命周期的运行状态。因此，静态mWebview始终只有一个片段intstance，mWebview没有根据你的选择而改变。

导航工作在一个webview而不是另一个 - Android Studio

1 个答案: