Android 操作栏图标未显示。没有看到 XML？

Question

问题：

• 图标未显示在新应用的操作栏上。 （兼容性 2.1+）

疑难解答：

• 确保已安装 Android 支持存储库和 Android 支持库。
• 四个搜索图标已下载并放置在 res/drawable/ic_action_search.png 目录中（引用正确？我在代码中省略了“.png”。）
• 确保该库已添加到 build.gradle(Module: app) 依赖方法中。 （也许编译错了？）
• 尝试将 action_settings 项设置为“始终”，没有更改，仍默认为下拉菜单。 （这就是让我觉得我的 xml 没有被识别的原因。如果这不起作用，我的图标就不会出现。）
• 我已经对我的版本进行了三次检查，以尝试使其与 2.1 及更高版本兼容，但我的第一个应用程序可能在此处出现问题，因此请检查此处以确保我添加了我的库，正在引用它们正确，并且我的版本号没有弄乱。
• 确保我的标题在 strings.xml 中就位
• 尝试将 [app:actionViewClass="android.support.v7.widget.SearchView"] 添加到我的 main_activity_actions.xml 中的项目

代码文件：

MainActivity.java

package com.example.alec.myapplication;

import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.content.Intent;
import android.view.View;
import android.widget.EditText;


public class MainActivity extends ActionBarActivity {
    public final static String EXTRA_MESSAGE = "com.mycompany.myfirstapp.MESSAGE";

    /** Called when the user clicks the Send button */
    public void sendMessage(View view) {
        Intent intent = new Intent(this, DisplayMessageActivity.class);
        EditText editText = (EditText) findViewById(R.id.edit_message);
        String message = editText.getText().toString();
        intent.putExtra(EXTRA_MESSAGE, message);
        startActivity(intent);
    }

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


    @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_main, 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.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}

build.gradle (Module:app)

apply plugin: 'com.android.application'

android {
    compileSdkVersion 21
    buildToolsVersion "21.1.2"

    defaultConfig {
        applicationId "com.example.alec.myapplication"
        minSdkVersion 8
        targetSdkVersion 17
        versionCode 1
        versionName "1.0"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    //compile 'com.android.support:appcompat-v7:21.0.3' Removed as I added the line below
    compile 'com.android.support:appcompat-v7:18.0.+'
}

DisplayMessageActivity.java

package com.example.alec.myapplication;

import android.content.Intent;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.TextView;


public class DisplayMessageActivity extends ActionBarActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //Receive the intent
        Intent intent = getIntent();
        String message = intent.getStringExtra(MainActivity.EXTRA_MESSAGE);
        //Display the message
        TextView textView = new TextView(this);
        textView.setTextSize(40);
        textView.setText(message);
        //Set the text view as the activity layout
        setContentView(textView);
    }

    @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.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}

main_activity_actions.xml

<?xml version="1.0" encoding="utf-8"?>
<menu   xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto">
    <!-- Search, should appear as action button -->
    <item android:id="@+id/action_search"
        android:icon="@drawable/ic_action_search"
        android:title="@string/action_search_title"
        app:showAsAction="ifRoom"
        app:actionViewClass="android.support.v7.widget.SearchView"/>
    <!-- Settings, should always be in the overflow -->
    <item android:id="@+id/action_settings"
        android:title="@string/action_settings"
        app:showAsAction="always" 
        app:actionViewClass="android.support.v7.widget.SearchView"/>
</menu>

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.alec.myapplication" >
    <uses-sdk android:minSdkVersion="7"
              android:targetSdkVersion="17"/>
    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/Theme.AppCompat.Light" >
        <activity
            android:name=".MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity
            android:name=".DisplayMessageActivity"
            android:label="@string/title_activity_display_message"
            android:parentActivityName=".MainActivity" >
            <meta-data
                android:name="android.support.PARENT_ACTIVITY"
                android:value="com.example.alec.myapplication.MainActivity" />
        </activity>
    </application>

</manifest>

字符串.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>

    <string name="app_name">My First App</string>
    <string name="edit_message">Enter a message</string>
    <string name="button_send">Send</string>
    <string name="action_settings">Settings</string>
    <string name="title_activity_main">MainActivity</string>
    <string name="title_activity_display_message">My Message</string>
    <string name="hello_world">Hello world!</string>
    <string name="action_search_title">Search</string>

</resources>

Answer 1

在 MainActivity 的 onCreateOptionsMenu 方法中，它说

getMenuInflater().inflate(R.menu.menu_main, menu);

但是你的菜单 xml 的名称是 main_activity_actions.xml。尝试将其更改为

getMenuInflater().inflate(R.menu.main_activity_actions, menu);