How to add a back button to action bar / toolbar

Question

I have written a piece of code as part of an app where I want to implement a back button on the action bar/tool bar such that when the button is pressed, the previous page (the page/fragment immediately before the current page/fragment) will be displayed.

This is the code for the ToolBar, DrawerLayout, NavigationView and getSupportActionBar():

final DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
final NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);

android.support.v7.widget.Toolbar toolbar = (android.support.v7.widget.Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
toolbar.setVisibility(View.VISIBLE);
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
getSupportActionBar().setLogo(R.mipmap.ic_launcher);
getSupportActionBar().setDisplayUseLogoEnabled(true);
getSupportActionBar().setHomeButtonEnabled(true);

I am unable to use ActionBar. For some reason (I don't know why), my Android studio/ program, will not allow me to use the ActionBar. So I am substituting that with the set/getSupportActionBar().

The function used in relation to this are:

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

@Override
public boolean onOptionsItemSelected(MenuItem item) {

     // Handle action bar item clicks here. The action bar will
     // automatically handle clicks on the Home/Up button, so long
     // as you specify a parent activity in AndroidManifest.xml.

     int id = item.getItemId();

     switch (id) {
         case android.R.id.home:
             onBackPressed();
             return true;
         default:
             return super.onOptionsItemSelected(item);
         }
    }        

@Override
public void onBackPressed() {

    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    if (drawer.isDrawerOpen(GravityCompat.START)) {
        drawer.closeDrawer(GravityCompat.START);
    } else {
        super.onBackPressed();        
    }
}

My activity_main.xml file is:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    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"
    android:fitsSystemWindows="true"
    android:id="@+id/activity_main"
    android:orientation="vertical"
    tools:openDrawer="start"
    tools:context="com.example.albin.settings_menu.SettingsActivity">

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="#fff">

    <android.support.v7.widget.Toolbar
            xmlns:android="http://schemas.android.com/apk/res/android"
            xmlns:app="http://schemas.android.com/apk/res-auto"
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:background="?attr/colorPrimary"
            app:popupTheme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
            app:title="Settings"/>

    <android.support.v4.widget.DrawerLayout
            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:id="@+id/drawer_layout"
            android:layout_width="match_parent"
            android:layout_height="match_parent">

        <FrameLayout
        android:id="@+id/frame"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/toolbar">

        </FrameLayout>

            <android.support.design.widget.NavigationView
                xmlns:android="http://schemas.android.com/apk/res/android"
                xmlns:app="http://schemas.android.com/apk/res-auto"
                android:id="@+id/nav_view"
                android:layout_width="wrap_content"
                android:layout_height="match_parent"
                android:layout_gravity="start"
                android:fitsSystemWindows="true"
                android:layout_marginTop="-24dp"
                app:menu="@menu/options_menu" />


        </android.support.v4.widget.DrawerLayout>

    </RelativeLayout>
    </LinearLayout>

The problem is that I don't know which is the useful code, which is the useless code and how to mix/join/(add additional codes to) these (codes, methods, variables/objects, fragments, xml layouts) to get the desired outcome, that is, the application of a back button on the action bar/tool bar.

Most of the code above is implemented for the up button, not the back button. I have read at several places that up and back buttons are not the same.

I tried several links on internet as well as on this site, but none of them has just what I need.

Hope someone can give me an clear answer...

Answer 1

You can include the back icon in ToolBar:

Initialize ToolBar:

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

• You can use an drawable icon as a back button.

  toolbar.setNavigationIcon(R.drawable.your_drawable_icon);
  
  toolbar.setNavigationOnClickListener(new View.OnClickListener() {
      @Override
      public void onClick(View v) {
          // what do you want here
      }
  });
  

• If you do not want to use drawable icon then:

  getSupportActionBar().setDisplayHomeAsUpEnabled(true);
  getSupportActionBar().setDisplayShowHomeEnabled(true);
  
  toolbar.setNavigationOnClickListener(new View.OnClickListener() {
      @Override
      public void onClick(View v) {
          // what do you want here
      }
  });
  

Answer 2

Actually your layout having that issue because you have added toolbar in RelativeLayout so drawer layout is overlapping on it that's why you would not able to click on back arrow, i have fix your layout see below

 <?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true"
    android:orientation="vertical">

    <android.support.v7.widget.Toolbar
        android:id="@+id/toolbar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="?attr/colorPrimary"
        app:navigationIcon="@drawable/ic_back_black"
        app:popupTheme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
        app:title="Settings" />

    <android.support.v4.widget.DrawerLayout
        android:id="@+id/drawer_layout"
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <FrameLayout
            android:id="@+id/frame"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_below="@+id/toolbar" />

        <android.support.design.widget.NavigationView
            android:id="@+id/nav_view"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_gravity="start"
            android:fitsSystemWindows="true"
            app:menu="@menu/options_menu" />
    </android.support.v4.widget.DrawerLayout>
</LinearLayout>