Question

我使用以下代码发送电子邮件

public class Mail extends Activity{

    public void send(String mail, String subject) {
        Intent intent = new Intent(Intent.ACTION_SEND);
        intent.putExtra(Intent.EXTRA_SUBJECT, subject);
        intent.putExtra(Intent.EXTRA_EMAIL, new String[]{mail});
        intent.putExtra(Intent.EXTRA_TEXT, "Some text");
        startActivity(intent);  
    }
}

但我在NullPointerException

中获得了startActivity(intent)...

我的权限：

<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.WRITE_INTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_INTERNAL_STORAGE" />

我不知道是什么原因。有人能帮助我吗？

   06-12 18:28:22.840: E/AndroidRuntime(11859): FATAL EXCEPTION: main

    06-12 18:28:22.840: E/AndroidRuntime(11859): java.lang.NullPointerException

    06-12 18:28:22.840: E/AndroidRuntime(11859):    at android.content.ContextWrapper.getPackageManager(ContextWrapper.java:86)

    06-12 18:28:22.840: E/AndroidRuntime(11859):    at puma.export_and_send.Mail.send(Mail.java:20)

    06-12 18:28:22.840: E/AndroidRuntime(11859):    at puma.dialogs.JourneyDialog$8.onClick(JourneyDialog.java:175)

    06-12 18:28:22.840: E/AndroidRuntime(11859):    at com.android.internal.app.AlertController$ButtonHandler.handleMessage(AlertController.java:166)  

    06-12 18:28:22.840: E/AndroidRuntime(11859):    at android.os.Handler.dispatchMessage(Handler.java:99)

    06-12 18:28:22.840: E/AndroidRuntime(11859):    at android.os.Looper.loop(Looper.java:137)

    06-12 18:28:22.840: E/AndroidRuntime(11859):    at android.app.ActivityThread.main(ActivityThread.java:4802)

    06-12 18:28:22.840: E/AndroidRuntime(11859):    at java.lang.reflect.Method.invokeNative(Native Method)

    06-12 18:28:22.840: E/AndroidRuntime(11859):    at java.lang.reflect.Method.invoke(Method.java:511)

    06-12 18:28:22.840: E/AndroidRuntime(11859):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:813)

    06-12 18:28:22.840: E/AndroidRuntime(11859):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:580)

    06-12 18:28:22.840: E/AndroidRuntime(11859):    at dalvik.system.NativeStart.main(Native Method)

Answer 1

试

Intent emailIntent = new Intent(Intent.ACTION_SENDTO, Uri.fromParts("mailto", "test@test.com", null));
        emailIntent.putExtra(Intent.EXTRA_SUBJECT, subject);
        emailIntent.putExtra(Intent.EXTRA_TEXT, "");
        startActivity(Intent.createChooser(emailIntent, "Email"));

Answer 2

检查变量subject和mail的值，其中一个必须具有null值！

public void send(String mail, String subject) {
    Intent intent = new Intent(Intent.ACTION_SEND);
    intent.putExtra(Intent.EXTRA_SUBJECT, subject);
    intent.putExtra(Intent.EXTRA_EMAIL, new String[]{mail});
    intent.putExtra(Intent.EXTRA_TEXT, "Some text");
    startActivity(intent);  
}

要避免这种情况，您将添加验证并在Toast中显示消息：

public void send(String mail, String subject) {
    if(mail!=null && subject != null){
        Intent intent = new Intent(Intent.ACTION_SEND);
        intent.putExtra(Intent.EXTRA_SUBJECT, subject);
        intent.putExtra(Intent.EXTRA_EMAIL, new String[]{mail});
        intent.putExtra(Intent.EXTRA_TEXT, "Some text");
        startActivity(intent);  
    }else{
        Toast.makeText(getApplicationContext(), "Cannot execute, one of the values \"mail\" or \"subject\" is NULL!" , Toast.LENGTH_LONG).show();             
    }
}

Answer 3

检查mail，subject不是null

public void send(String mail, String subject) {
    Intent intent = new Intent(Intent.ACTION_SEND);
    intent.putExtra(Intent.EXTRA_SUBJECT, subject);
    intent.putExtra(Intent.EXTRA_EMAIL, new String[]{mail});
    intent.putExtra(Intent.EXTRA_TEXT, "Some text");

    // Verify that the intent will resolve to an activity
    if (sendIntent.resolveActivity(getPackageManager()) != null) {
       startActivity(intent);  
    }

}

发送implicit Intent

的最佳方式

Answer 4

Might be because the launcher doesn't recognize the e-mail app, Try by using Chooser

  intent = new Intent(Intent.ACTION_SEND);
                intent.setData(Uri.parse("mailto:"));
                String[] to ={"XX","XX "};
                intent.putExtra(Intent.EXTRA_EMAIL,to);
                intent.putExtra(Intent.EXTRA_SUBJECT,"XX");
                intent.putExtra(Intent.EXTRA_TEXT,"This E-mail has been sent by the Customer through XX");
                intent.setType("message/rfc822");
                chooser = Intent.createChooser(intent,"Send Email");
                startActivity(chooser);

通过Intent发送电子邮件时出现NullPointerException

4 个答案: