java - onCreateOptionsMenu 时失败

Question

我是新手 Android 程序员，所以我想为我的应用程序制作菜单，但当我尝试将其启动到 AVD 时出现一些错误这是我的代码:

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.Menu;
public class MainActivity extends AppCompatActivity {

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

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.main_menu,menu);
        return super.onCreateOptionsMenu(menu);
    }
    }

这是我的 XML 主目录

<android.support.constraint.ConstraintLayout 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.simasjiwa.testingheadermenu.MainActivity">

这是我尝试创建的菜单:

  <?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">
    <item android:icon="@mipmap/ic_launcher"
        android:title="clickhere"
        android:onClick="doAction"
        app:showAsAction="always"
        android:id="@+id/testing"></item>

</menu>

这是我的 logcat 错误:

FATAL EXCEPTION: main
                                                                           Process: com.simasjiwa.testingheadermenu, PID: 8322
                                                                           android.view.InflateException: Couldn't resolve menu item onClick handler doAction in class com.simasjiwa.testingheadermenu.MainActivity
                                                                               at android.support.v7.view.SupportMenuInflater$InflatedOnMenuItemClickListener.<init>(SupportMenuInflater.java:248)
                                                                               at android.support.v7.view.SupportMenuInflater$MenuState.setItem(SupportMenuInflater.java:448)
                                                                               at android.support.v7.view.SupportMenuInflater$MenuState.addItem(SupportMenuInflater.java:483)
                                                                               at android.support.v7.view.SupportMenuInflater.parseMenu(SupportMenuInflater.java:200)
                                                                               at android.support.v7.view.SupportMenuInflater.inflate(SupportMenuInflater.java:122)
                                                                               at com.simasjiwa.testingheadermenu.MainActivity.onCreateOptionsMenu(MainActivity.java:17)
                                                                               at android.app.Activity.onCreatePanelMenu(Activity.java:2538)
                                                                               at android.support.v4.app.FragmentActivity.onCreatePanelMenu(FragmentActivity.java:362)
                                                                               at android.support.v7.view.WindowCallbackWrapper.onCreatePanelMenu(WindowCallbackWrapper.java:98)
                                                                               at android.support.v7.app.AppCompatDelegateImplBase$AppCompatWindowCallbackBase.onCreatePanelMenu(AppCompatDelegateImplBase.java:335)
                                                                               at android.support.v7.app.AppCompatDelegateImplV9.preparePanel(AppCompatDelegateImplV9.java:1368)
                                                                               at android.support.v7.app.AppCompatDelegateImplV9.doInvalidatePanelMenu(AppCompatDelegateImplV9.java:1648)
                                                                               at android.support.v7.app.AppCompatDelegateImplV9$1.run(AppCompatDelegateImplV9.java:140)
                                                                               at android.os.Handler.handleCallback(Handler.java:733)
                                                                               at android.os.Handler.dispatchMessage(Handler.java:95)
                                                                               at android.os.Looper.loop(Looper.java:136)
                                                                               at android.app.ActivityThread.main(ActivityThread.java:5017)
                                                                               at java.lang.reflect.Method.invokeNative(Native Method)
                                                                               at java.lang.reflect.Method.invoke(Method.java:515)
                                                                               at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
                                                                               at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
                                                                               at dalvik.system.NativeStart.main(Native Method)
                                                                            Caused by: java.lang.NoSuchMethodException: doAction [interface android.view.MenuItem]
                                                                               at java.lang.Class.getConstructorOrMethod(Class.java:472)
                                                                               at java.lang.Class.getMethod(Class.java:857)
                                                                               at android.support.v7.view.SupportMenuInflater$InflatedOnMenuItemClickListener.<init>(SupportMenuInflater.java:244)
                                                                               at android.support.v7.view.SupportMenuInflater$MenuState.setItem(SupportMenuInflater.java:448) 
                                                                               at android.support.v7.view.SupportMenuInflater$MenuState.addItem(SupportMenuInflater.java:483) 
                                                                               at android.support.v7.view.SupportMenuInflater.parseMenu(SupportMenuInflater.java:200) 
                                                                               at android.support.v7.view.SupportMenuInflater.inflate(SupportMenuInflater.java:122) 
                                                                               at com.simasjiwa.testingheadermenu.MainActivity.onCreateOptionsMenu(MainActivity.java:17) 
                                                                               at android.app.Activity.onCreatePanelMenu(Activity.java:2538) 
                                                                               at android.support.v4.app.FragmentActivity.onCreatePanelMenu(FragmentActivity.java:362) 
                                                                               at android.support.v7.view.WindowCallbackWrapper.onCreatePanelMenu(WindowCallbackWrapper.java:98) 
                                                                               at android.support.v7.app.AppCompatDelegateImplBase$AppCompatWindowCallbackBase.onCreatePanelMenu(AppCompatDelegateImplBase.java:335) 
                                                                               at android.support.v7.app.AppCompatDelegateImplV9.preparePanel(AppCompatDelegateImplV9.java:1368) 
                                                                               at android.support.v7.app.AppCompatDelegateImplV9.doInvalidatePanelMenu(AppCompatDelegateImplV9.java:1648) 
                                                                               at android.support.v7.app.AppCompatDelegateImplV9$1.run(AppCompatDelegateImplV9.java:140) 
                                                                               at android.os.Handler.handleCallback(Handler.java:733) 
                                                                               at android.os.Handler.dispatchMessage(Handler.java:95) 
                                                                               at android.os.Looper.loop(Looper.java:136) 
                                                                               at android.app.ActivityThread.main(ActivityThread.java:5017) 
                                                                               at java.lang.reflect.Method.invokeNative(Native Method) 
                                                                               at java.lang.reflect.Method.invoke(Method.java:515) 
                                                                               at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779) 
                                                                               at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595) 
                                                                               at dalvik.system.NativeStart.main(Native Method) 

我的问题是，为什么我可以跑到AVD？我的代码是错误的还是我忘记插入的东西？先谢谢了

Answer 1

您的 MainActivity 中没有针对 android:onClick="doAction" 的相应处理程序，因此您可以添加它

public class MainActivity extends AppCompatActivity {

    // fields
    // other methods
    public void doAction(MenuItem item){
       // perform your action here 
    }
}

注意:它 supports API Level 11或以上，否则使用 onOptionsItemSelected