having Problem with adding menu to an app - android-studio

Question

I'm trying to add some menus to my app. here is my code:
java code:
package com.example.excercise;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import android.app.Activity;
import android.content.Intent;
import android.graphics.Color;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
import java.util.Date;
import java.util.Random;
public class MainActivity extends AppCompatActivity {
TextView my_text;
Button button;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
my_text=findViewById(R.id.textView);
my_text.setText(new Date().toString());
button = findViewById(R.id.button);
button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Random random=new Random();
my_text.setTextColor(Color.rgb(random.nextInt(256),random.nextInt(256),random.nextInt(256)));
}
});
button.setOnLongClickListener(new View.OnLongClickListener() {
#Override
public boolean onLongClick(View view) {
Intent intent = new Intent(MainActivity.this,SecondActivity.class);
startActivity(intent);
return true;
}
});
}
#Override
protected void onResume() {
super.onResume();
Toast.makeText(this, "MainActivity: OnResume()", Toast.LENGTH_SHORT).show();
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.main_menu,menu);
return super.onCreateOptionsMenu(menu);
}
}
main_menu xml:
<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:android="http://schemas.android.com/apk/res/android">
<item android:title="Item1"/>
<item android:title="Item2"/>
<item android:title="Item3"/>
<item
android:id="#+id/app_bar_search"
android:icon="#drawable/ic_search_black_24dp"
android:title="Search"
app:actionViewClass="android.widget.SearchView"/>
<item android:title="Item4">
<menu>
<item android:title="SubItem1"
android:onClick="itemClick"/>
<item android:title="SubItem2"/>
</menu>
</item>
I'm getting this message in red in logcat :
2019-07-14 02:49:18.148 6160-6160/com.example.excercise
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.excercise, PID: 6160
android.view.InflateException: Couldn't resolve menu item onClick handler itemClick in class com.example.excercise.MainActivity
at androidx.appcompat.view.SupportMenuInflater$InflatedOnMenuItemClickListener.(SupportMenuInflater.java:254)
at androidx.appcompat.view.SupportMenuInflater$MenuState.setItem(SupportMenuInflater.java:482)
at androidx.appcompat.view.SupportMenuInflater$MenuState.addItem(SupportMenuInflater.java:530)
at androidx.appcompat.view.SupportMenuInflater.parseMenu(SupportMenuInflater.java:206)
at androidx.appcompat.view.SupportMenuInflater.parseMenu(SupportMenuInflater.java:184)
at androidx.appcompat.view.SupportMenuInflater.inflate(SupportMenuInflater.java:128)
at com.example.excercise.MainActivity.onCreateOptionsMenu(MainActivity.java:69)
at android.app.Activity.onCreatePanelMenu(Activity.java:4055)
at androidx.fragment.app.FragmentActivity.onCreatePanelMenu(FragmentActivity.java:378)
at androidx.appcompat.view.WindowCallbackWrapper.onCreatePanelMenu(WindowCallbackWrapper.java:94)
at androidx.appcompat.app.AppCompatDelegateImpl$AppCompatWindowCallback.onCreatePanelMenu(AppCompatDelegateImpl.java:2549)
at androidx.appcompat.app.AppCompatDelegateImpl.preparePanel(AppCompatDelegateImpl.java:1589)
at androidx.appcompat.app.AppCompatDelegateImpl.doInvalidatePanelMenu(AppCompatDelegateImpl.java:1869)
at androidx.appcompat.app.AppCompatDelegateImpl$2.run(AppCompatDelegateImpl.java:230)
at android.os.Handler.handleCallback(Handler.java:883)
at android.os.Handler.dispatchMessage(Handler.java:100)
at android.os.Looper.loop(Looper.java:214)
at android.app.ActivityThread.main(ActivityThread.java:7319)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:934)
Caused by: java.lang.NoSuchMethodException: com.example.excercise.MainActivity.itemClick [interface
android.view.MenuItem]
at java.lang.Class.getMethod(Class.java:2072)
at java.lang.Class.getMethod(Class.java:1693)
at androidx.appcompat.view.SupportMenuInflater$InflatedOnMenuItemClickListener.(SupportMenuInflater.java:250)
at androidx.appcompat.view.SupportMenuInflater$MenuState.setItem(SupportMenuInflater.java:482)
at androidx.appcompat.view.SupportMenuInflater$MenuState.addItem(SupportMenuInflater.java:530)
at androidx.appcompat.view.SupportMenuInflater.parseMenu(SupportMenuInflater.java:206)
at androidx.appcompat.view.SupportMenuInflater.parseMenu(SupportMenuInflater.java:184)
at androidx.appcompat.view.SupportMenuInflater.inflate(SupportMenuInflater.java:128)
at com.example.excercise.MainActivity.onCreateOptionsMenu(MainActivity.java:69)
at android.app.Activity.onCreatePanelMenu(Activity.java:4055)
at androidx.fragment.app.FragmentActivity.onCreatePanelMenu(FragmentActivity.java:378)
at androidx.appcompat.view.WindowCallbackWrapper.onCreatePanelMenu(WindowCallbackWrapper.java:94)
at androidx.appcompat.app.AppCompatDelegateImpl$AppCompatWindowCallback.onCreatePanelMenu(AppCompatDelegateImpl.java:2549)
at androidx.appcompat.app.AppCompatDelegateImpl.preparePanel(AppCompatDelegateImpl.java:1589)
at androidx.appcompat.app.AppCompatDelegateImpl.doInvalidatePanelMenu(AppCompatDelegateImpl.java:1869)
at androidx.appcompat.app.AppCompatDelegateImpl$2.run(AppCompatDelegateImpl.java:230)
at android.os.Handler.handleCallback(Handler.java:883)
at android.os.Handler.dispatchMessage(Handler.java:100)
at android.os.Looper.loop(Looper.java:214)
at android.app.ActivityThread.main(ActivityThread.java:7319)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:934)
what is the problem and how should I fix it? I should add that in all java classes that red message refer me to, I get the "cannot resolve R symbol" error.

Answer 1

In your main_menu.xml add an id to the item element
<?xml version="1.0" encoding="utf-8"?>
<item android id="#+id/item1"
android:title="Item1"/>
<item android id="#+id/item2"
android:title="Item2"/>
<item android id="#+id/item3"
android:title="Item3"/>
In your MainActivity.java add onOptionsItemSelected method
#Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.main_menu,menu);
return super.onCreateOptionsMenu(menu);
}
public boolean onOptionsItemSelected(MenuItem item) {
//respond to menu item selection
switch (item.getItemId()) {
case R.id.item1:
Toast.makeText(this, "You clicked on item 1", Toast.LENGTH_SHORT).show();
return true;
case R.id.item2:
Toast.makeText(this, "You clicked on item 1", Toast.LENGTH_SHORT).show();
return true;
default:
return super.onOptionsItemSelected(item);
}
}
Finally to solve the cannot resolve R symbol error...You have not imported the R class into your java file.There are two steps to do that
Step One
Click on the R symbol you should see a red bulb...click on that red bulb...you'd see a popup showing import class...Click on import
Or Step Two
Click on the R symbol...Then Press Alt + Enter
I hope this helps...