android - android.support.v4.widget.DrawerLayout 没有菜单项？

Question

我无法在工具栏中获取菜单项。我正在为我的布局文件使用 android.support.v4.widget.DrawerLayout。

我有 menu_settings:

<menu 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"
    tools:context="com.example.shiza.muslimmemo.Settings">

    <item
        android:id="@+id/back"
        android:orderInCategory="100"
        android:title="Back"
        android:icon="@drawable/ic_keyboard_backspace"
        app:showAsAction="always" />

</menu>

和设置 Activity :

package com.example.shiza.muslimmemo;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;

public class Settings extends AppCompatActivity {

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

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().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();

        //noinspection SimplifiableIfStatement
        if (id == R.id.back) {
            Intent intent = new Intent(this,MainActivity.class);
            startActivity(intent);
        }

        return super.onOptionsItemSelected(item);
    }
}

最后是 settings_xml，

<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"
    tools:context="com.example.shiza.muslimmemo.Settings">


    <LinearLayout
        android:id="@+id/main_content"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical">

        <android.support.v7.widget.Toolbar
            android:id="@+id/app_bar"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:background="@color/colorPrimary"
            app:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar" />
    </LinearLayout>

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

但我在工具栏中看不到任何 ic_keyboard_backspace。请帮帮我。

Answer 1

我认为您应该将工具栏设置为窗口操作栏，否则AppCompatActivity 将不知道在哪里扩展菜单。尝试使用这个 onCreate 方法:

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_settings);
    Toolbar t = (Toolbar) findViewById(R.id.app_bar);
    setSupportActionBar(t);
}