从 getActionProvider() 设置 ShareActionProvider 时如何解析 Null?
How to resolve Null while setting ShareActionProvider from getActionProvider()?
我已经很努力了,还是无法解决问题。出现的错误是:
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ShareActionProvider.setShareIntent(android.content.Intent)' on a null object reference
at com.headfirst.bitsandpizza.MainActivity.setIntent(MainActivity.java:32)
at com.headfirst.bitsandpizza.MainActivity.onCreateOptionsMenu(MainActivity.java:24)
at android.app.Activity.onCreatePanelMenu(Activity.java:3568)
at com.android.internal.policy.PhoneWindow.preparePanel(PhoneWindow.java:681)
at com.android.internal.policy.PhoneWindow.doInvalidatePanelMenu(PhoneWindow.java:1074)
at com.android.internal.policy.PhoneWindow.run(PhoneWindow.java:295)
at android.os.Handler.handleCallback(Handler.java:873)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:214)
at android.app.ActivityThread.main(ActivityThread.java:7037)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:494)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:965)
应该发生的是,当他们单击菜单栏中的共享图标时,应用程序将向 orderActivty 发送一条消息。
当我 运行 它时,该应用程序不会打开。当我注释掉 setShareIntent() 时,它工作正常,但共享按钮不起作用。所以一定是哪里出了问题。
这是 MainActitvity 代码:
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.ShareActionProvider;
public class MainActivity extends Activity {
private ShareActionProvider shareActionProvider;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
@Override
public boolean onCreateOptionsMenu(Menu menu ){
getMenuInflater().inflate(R.menu.menu_main, menu);//dette legger til menyens
MenuItem menuItem = menu.findItem(R.id.action_share);
shareActionProvider = (ShareActionProvider)menuItem.getActionProvider();
setIntent("this is example text");
return super.onCreateOptionsMenu(menu);
}
private void setIntent(String text) {
Intent intent = new Intent(Intent.ACTION_SEND);
intent.setType("text/plain");
intent.putExtra(Intent.EXTRA_TEXT, text);
shareActionProvider.setShareIntent(intent);//TODO Feil med setShareIntent metoden
}
@Override
public boolean onOptionsItemSelected(MenuItem item ){
switch (item.getItemId()){
case R.id.action_create_order:
Intent intent = new Intent(this, OrderActivity.class);
startActivity(intent);
return true;
case R.id.action_settings:
return true;
default:
return super.onOptionsItemSelected(item);
}
}
}
这是我的 activy_main:
<?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"
tools:context=".MainActivity"
android:orientation="vertical">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Hello World!"
/>
</LinearLayout>
这是我的 menu_main 创建分享按钮的地方:
<?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:id="@+id/action_create_order"
android:title="@string/action_create_order"
android:icon="@drawable/ic_action_new_event"
android:orderInCategory="1"
app:showAsAction="ifRoom" />
<item
android:id="@+id/action_share"
android:title="@string/action_share"
android:orderInCategory="2"
app:showAsAction="ifRoom"
app:actionProviderClass="android.widget.ShareActionProvider" />
<item
android:id="@+id/action_settings"
android:title="@string/action_settings"
android:orderInCategory="100"
app:showAsAction="never"/>
</menu>
这是我的清单:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.headfirst.bitsandpizza">
<application
android:allowBackup="true"
android:icon="@mipmap/pizzalogo"
android:label="@string/app_name"
android:roundIcon="@mipmap/pizzalogo"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name=".OrderActivity"
android:label="@string/action_create_order"
android:parentActivityName=".MainActivity">
<meta-data
android:name="android.support.PARENT_ACTIVITY"
android:value=".MainActivity" />
</activity>
</application>
</manifest>
这是订单活动:
import androidx.appcompat.app.AppCompatActivity;
import android.app.Activity;
import android.os.Bundle;
public class OrderActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_order);
}
}
这里是 activity_order:
<?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"
tools:context=".OrderActivity"
android:orientation="vertical">
</LinearLayout>
您应该在这里考虑兼容性因素。
(ShareActionProvider) menuItem.getActionProvider() - 根据问题中的代码,这给出 NULL。
按照以下代码进行更改,应用程序将运行。
菜单
<item
android:id="@+id/action_share"
android:title="share"
android:orderInCategory="2"
app:showAsAction="ifRoom"
app:actionProviderClass="androidx.appcompat.widget.ShareActionProvider" />
清单文件
android:theme="@style/Theme.AppCompat">
Activity
import androidx.appcompat.app.AppCompatActivity;
import androidx.appcompat.widget.ShareActionProvider;
import androidx.core.view.MenuItemCompat;
public class ShareActivity extends AppCompatActivity {
private ShareActionProvider shareActionProvider;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_share);
}
@Override
public boolean onCreateOptionsMenu(Menu menu ){
getMenuInflater().inflate(R.menu.menu_main, menu);//dette legger til menyens
MenuItem menuItem = menu.findItem(R.id.action_share);
shareActionProvider = (ShareActionProvider) MenuItemCompat.getActionProvider(menuItem);
setIntent("this is example text");
return super.onCreateOptionsMenu(menu);
}
private void setIntent(String text) {
Intent intent = new Intent(Intent.ACTION_SEND);
intent.setType("text/plain");
intent.putExtra(Intent.EXTRA_TEXT, text);
shareActionProvider.setShareIntent(intent);//TODO Feil med setShareIntent metoden
}
我已经很努力了,还是无法解决问题。出现的错误是:
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ShareActionProvider.setShareIntent(android.content.Intent)' on a null object reference
at com.headfirst.bitsandpizza.MainActivity.setIntent(MainActivity.java:32)
at com.headfirst.bitsandpizza.MainActivity.onCreateOptionsMenu(MainActivity.java:24)
at android.app.Activity.onCreatePanelMenu(Activity.java:3568)
at com.android.internal.policy.PhoneWindow.preparePanel(PhoneWindow.java:681)
at com.android.internal.policy.PhoneWindow.doInvalidatePanelMenu(PhoneWindow.java:1074)
at com.android.internal.policy.PhoneWindow.run(PhoneWindow.java:295)
at android.os.Handler.handleCallback(Handler.java:873)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:214)
at android.app.ActivityThread.main(ActivityThread.java:7037)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:494)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:965)
应该发生的是,当他们单击菜单栏中的共享图标时,应用程序将向 orderActivty 发送一条消息。 当我 运行 它时,该应用程序不会打开。当我注释掉 setShareIntent() 时,它工作正常,但共享按钮不起作用。所以一定是哪里出了问题。
这是 MainActitvity 代码:
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.ShareActionProvider;
public class MainActivity extends Activity {
private ShareActionProvider shareActionProvider;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
@Override
public boolean onCreateOptionsMenu(Menu menu ){
getMenuInflater().inflate(R.menu.menu_main, menu);//dette legger til menyens
MenuItem menuItem = menu.findItem(R.id.action_share);
shareActionProvider = (ShareActionProvider)menuItem.getActionProvider();
setIntent("this is example text");
return super.onCreateOptionsMenu(menu);
}
private void setIntent(String text) {
Intent intent = new Intent(Intent.ACTION_SEND);
intent.setType("text/plain");
intent.putExtra(Intent.EXTRA_TEXT, text);
shareActionProvider.setShareIntent(intent);//TODO Feil med setShareIntent metoden
}
@Override
public boolean onOptionsItemSelected(MenuItem item ){
switch (item.getItemId()){
case R.id.action_create_order:
Intent intent = new Intent(this, OrderActivity.class);
startActivity(intent);
return true;
case R.id.action_settings:
return true;
default:
return super.onOptionsItemSelected(item);
}
}
}
这是我的 activy_main:
<?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"
tools:context=".MainActivity"
android:orientation="vertical">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Hello World!"
/>
</LinearLayout>
这是我的 menu_main 创建分享按钮的地方:
<?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:id="@+id/action_create_order"
android:title="@string/action_create_order"
android:icon="@drawable/ic_action_new_event"
android:orderInCategory="1"
app:showAsAction="ifRoom" />
<item
android:id="@+id/action_share"
android:title="@string/action_share"
android:orderInCategory="2"
app:showAsAction="ifRoom"
app:actionProviderClass="android.widget.ShareActionProvider" />
<item
android:id="@+id/action_settings"
android:title="@string/action_settings"
android:orderInCategory="100"
app:showAsAction="never"/>
</menu>
这是我的清单:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.headfirst.bitsandpizza">
<application
android:allowBackup="true"
android:icon="@mipmap/pizzalogo"
android:label="@string/app_name"
android:roundIcon="@mipmap/pizzalogo"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name=".OrderActivity"
android:label="@string/action_create_order"
android:parentActivityName=".MainActivity">
<meta-data
android:name="android.support.PARENT_ACTIVITY"
android:value=".MainActivity" />
</activity>
</application>
</manifest>
这是订单活动:
import androidx.appcompat.app.AppCompatActivity;
import android.app.Activity;
import android.os.Bundle;
public class OrderActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_order);
}
}
这里是 activity_order:
<?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"
tools:context=".OrderActivity"
android:orientation="vertical">
</LinearLayout>
您应该在这里考虑兼容性因素。
(ShareActionProvider) menuItem.getActionProvider() - 根据问题中的代码,这给出 NULL。
按照以下代码进行更改,应用程序将运行。
菜单
<item
android:id="@+id/action_share"
android:title="share"
android:orderInCategory="2"
app:showAsAction="ifRoom"
app:actionProviderClass="androidx.appcompat.widget.ShareActionProvider" />
清单文件
android:theme="@style/Theme.AppCompat">
Activity
import androidx.appcompat.app.AppCompatActivity;
import androidx.appcompat.widget.ShareActionProvider;
import androidx.core.view.MenuItemCompat;
public class ShareActivity extends AppCompatActivity {
private ShareActionProvider shareActionProvider;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_share);
}
@Override
public boolean onCreateOptionsMenu(Menu menu ){
getMenuInflater().inflate(R.menu.menu_main, menu);//dette legger til menyens
MenuItem menuItem = menu.findItem(R.id.action_share);
shareActionProvider = (ShareActionProvider) MenuItemCompat.getActionProvider(menuItem);
setIntent("this is example text");
return super.onCreateOptionsMenu(menu);
}
private void setIntent(String text) {
Intent intent = new Intent(Intent.ACTION_SEND);
intent.setType("text/plain");
intent.putExtra(Intent.EXTRA_TEXT, text);
shareActionProvider.setShareIntent(intent);//TODO Feil med setShareIntent metoden
}