回到主页按钮不会出现。我该怎么办

Question

回到主页按钮不会出现。

我加入这个代码，并没有再次出现：

getActionBar（）setDisplayHomeAsUpEnabled（真）。

我应该怎么做才能显示后退按钮？

我的动态

package com.kamu.kamu_bilgi; 

import android.content.Intent; 
import android.graphics.Bitmap; 
import android.os.Bundle; 
import android.os.Handler; 
import android.support.v7.app.AppCompatActivity; 
import android.support.v7.widget.Toolbar; 
import android.view.KeyEvent; 
import android.view.Menu; 
import android.view.MenuInflater; 
import android.view.MenuItem; 
import android.webkit.WebSettings; 
import android.webkit.WebView; 
import android.webkit.WebViewClient; 

public class ekran18 extends AppCompatActivity { 


    private WebView mWebView; 

    private Menu optionsMenu; 

    @Override 
    public boolean onCreateOptionsMenu(Menu menu) {//Menüyü oluşturuyoruz 
     this.optionsMenu = menu; 

     MenuInflater inflater = getMenuInflater();// inflater herhangi bir view ın java objesine dönüştürülüp düzenlenmesinde yardımcı olur.Burda menü düzenlenmesi için kullanacağız 
     inflater.inflate(R.menu.main_activity_actions, menu);//Xml olarak oluşturduğumuz menü yü alıyoruz 

     return super.onCreateOptionsMenu(menu); 
    } 


    @Override 
    public boolean onOptionsItemSelected(MenuItem item) {// Action Bar itemden herhangi biri tıklandığında 

     switch (item.getItemId()) { 

      case R.id.action_settings: //settings iconu tıklandığında 

       settings(); 

       break; 


      case R.id.action_paylas: //share iconu 

       share(); 

       break; 


      case R.id.action_yenile://refresh iconu 

       refresh(); 

       return true; 

      case android.R.id.home: 
       // app icon in action bar clicked; goto parent activity. 
       this.finish(); 
       return true; 


      default: 
       return super.onOptionsItemSelected(item); 
     } 
     return true; 
    } 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.sayfa18); 


     mWebView = (WebView) findViewById(R.id.webView); 

     assert mWebView != null; 
     WebSettings webSettings = mWebView.getSettings(); 
     webSettings.setJavaScriptEnabled(true); 
     mWebView.loadUrl("http://www.kamu.com/kamupersoneli/ilanlar/"); 
     mWebView.setWebViewClient(new HelloWebViewClient()); 

     Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar2); 
     setSupportActionBar(toolbar); 


    } 

    private class HelloWebViewClient extends WebViewClient{ 


     @Override 
     public void onPageStarted(WebView view, String url, Bitmap favicon) { 
      // TODO Auto-generated method stub 
      super.onPageStarted(view, url, favicon); 
     } 

     @Override 
     public boolean shouldOverrideUrlLoading(WebView webView, String url) 
     { 
      webView.loadUrl(url); 
      return true; 
     } 
    } 
    @Override 
    public boolean onKeyDown(int keyCode, KeyEvent event) 
    { //if back key is pressed 
     if((keyCode == KeyEvent.KEYCODE_BACK)&& mWebView.canGoBack()) 
     { 
      mWebView.goBack(); 
      return true; 

     } 

     return super.onKeyDown(keyCode, event); 

    } 

    public void share(){ 
     Intent sharingIntent = new Intent(android.content.Intent.ACTION_SEND); 
     sharingIntent.setType("text/plain"); 
     String shareMesaj = ""; 
     sharingIntent.putExtra(android.content.Intent.EXTRA_SUBJECT, ""); 
     sharingIntent.putExtra(Intent.EXTRA_TEXT, mWebView.getUrl()); 
     startActivity(Intent.createChooser(sharingIntent, "")); 

    } 
    public void settings(){ 
     Intent myIntent = new Intent(getApplicationContext(), Ayarlar.class); 
     startActivity(myIntent); 

    } 
    public void refresh(){ 

     setRefreshActionButtonState(true);//progress bar refresh iconla değişecek ve çalışacak . 
     mWebView.reload(); 
     final Handler handler = new Handler(); 
     handler.postDelayed(new Runnable() { 
      @Override 
      public void run() { 
       setRefreshActionButtonState(false);//3 sn sonra duracak ve refresh iconu geri gelecek. Siz bu arada başka işlemler sunucu bağlantısı vs.. yapabilirsiniz 

      } 
     }, 3000); 
    } 
    public void setRefreshActionButtonState(final boolean refreshing) { 

     //bu method refresh iteme tıklandığında progress bar gözükmesi için 
     if (optionsMenu != null) { 
      final MenuItem refreshItem = optionsMenu 
        .findItem(R.id.action_yenile); 
      if (refreshItem != null) { 
       if (refreshing) { 
        refreshItem.setActionView(R.layout.actionbar_refresh_progress); 
       } else { 
        refreshItem.setActionView(null); 
       } 
      } 
     } 
    } 
} 

我AndroidManifest

<activity android:name=".ekran18" 
      android:label="@string/title_activity_sayfa18" 
      android:screenOrientation="fullSensor" 
      android:launchMode="singleTop" 
      android:configChanges="keyboardHidden|orientation|screenSize" 
      android:parentActivityName="com.kamubilgi.kamu_bilgi.MainActivity" 
      android:theme="@style/AppTheme.NoActionBar"> 
      <meta-data 
       android:name="android.support.PARENT_ACTIVITY" 
       android:value="com.kamubilgi.kamu_bilgi.MainActivity" /></activity> 

我的布局

<FrameLayout 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="com.kamubilgi.kamu_bilgi.ekran18"> 

    <!-- TODO: Update blank fragment layout --> 

    <RelativeLayout 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" 
     tools:ignore="UselessParent"> 

     <WebView 
      android:layout_width="match_parent" 
      android:layout_height="match_parent" 
      android:id="@+id/webView" > 

     </WebView> 

     <android.support.v7.widget.Toolbar 
      android:layout_width="match_parent" 
      android:layout_height="wrap_content" 
      android:background="@android:color/holo_red_dark" 
      android:theme="?attr/actionBarTheme" 
      android:minHeight="?attr/actionBarSize" 
      android:id="@+id/toolbar2" /> 

    </RelativeLayout> 

</FrameLayout> 

我的菜单

<menu xmlns:android="http://schemas.android.com/apk/res/android" 
    xmlns:app="http://schemas.android.com/apk/res-auto"> 
    <!-- Arama, eylem düğmesi olarak görülebilir --> 

    <item android:id="@+id/action_geri" 
     android:icon="@drawable/ic_keyboard_arrow_left_white_24px" 
     android:title="@string/action_arama" 
     app:showAsAction="always" 
     /> 
    <item android:id="@+id/action_paylas" 
     android:icon="@drawable/ic_share_white_24px" 
     android:title="@string/action_arama" 
     app:showAsAction="always" 
     /> 

    <item android:id="@+id/action_yenile" 
     android:icon="@drawable/ic_autorenew_white_24px" 
     android:title="@string/action_arama" 
     app:showAsAction="always" /> 


    <!-- Ayarlar, daima taşan eylemler bölümünde durabilir --> 
    <item android:id="@+id/action_ayarlar" 
     android:title="@string/action_settings" 
     app:showAsAction="never" /> 
</menu> 

Answer 1

这是你错过.. 机器人：主题= “@风格/ AppTheme.NoActionBar”

更改主题

或

添加工具栏里面的自定义布局/图