Getting Null pointer exception during String comparison

Question

I getting java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.lang.String.equals(java.lang.Object)' on a null object reference when passing class reference to a method. The line causing the error is:

if (!contactData.getContactNo().equals("")){

More of code:

Invocation of method:

recContDBHelper.insertRecord(new ContactData("", number, date)); <--Exception here

Invoked method:

 public void insertRecord(ContactData contactData) {
        String name = "";
        if (!contactData.getContactNo().equals("")) { <--exception here
            name = CommonServices.getContactDisplayNameByNumber(contactData.getContactNo(), context);
            if (name.equalsIgnoreCase("")) {
                name = contactData.getContactNo();
            }
        }
    }

In the above code contactData.getContactNo() return type is String.

Exception is:

04-12 18:21:40.153: E/AndroidRuntime(27924): FATAL EXCEPTION: main
04-12 18:21:40.153: E/AndroidRuntime(27924): Process: com.stackoverflow.ranjith.androidprojdel, PID: 27924
04-12 18:21:40.153: E/AndroidRuntime(27924): java.lang.RuntimeException: Unable to start receiver com.stackoverflow.ranjith.androidprojdel.PhoneCallreceiver: java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.lang.String.equals(java.lang.Object)' on a null object reference
04-12 18:21:40.153: E/AndroidRuntime(27924):    at android.app.ActivityThread.handleReceiver(ActivityThread.java:2586)
04-12 18:21:40.153: E/AndroidRuntime(27924):    at android.app.ActivityThread.access$1700(ActivityThread.java:144)
04-12 18:21:40.153: E/AndroidRuntime(27924):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1355)
04-12 18:21:40.153: E/AndroidRuntime(27924):    at android.os.Handler.dispatchMessage(Handler.java:102)
04-12 18:21:40.153: E/AndroidRuntime(27924):    at android.os.Looper.loop(Looper.java:135)
04-12 18:21:40.153: E/AndroidRuntime(27924):    at android.app.ActivityThread.main(ActivityThread.java:5221)
04-12 18:21:40.153: E/AndroidRuntime(27924):    at java.lang.reflect.Method.invoke(Native Method)
04-12 18:21:40.153: E/AndroidRuntime(27924):    at java.lang.reflect.Method.invoke(Method.java:372)
04-12 18:21:40.153: E/AndroidRuntime(27924):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
04-12 18:21:40.153: E/AndroidRuntime(27924):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
04-12 18:21:40.153: E/AndroidRuntime(27924): Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.lang.String.equals(java.lang.Object)' on a null object reference
04-12 18:21:40.153: E/AndroidRuntime(27924):    at com.stackoverflow.ranjith.androidprojdel.recentlyContacted.RecContDBHelper.insertRecord(RecContDBHelper.java:57)
04-12 18:21:40.153: E/AndroidRuntime(27924):    at com.stackoverflow.ranjith.androidprojdel.PhoneCallreceiver.onReceive(PhoneCallreceiver.java:93)
04-12 18:21:40.153: E/AndroidRuntime(27924):    at android.app.ActivityThread.handleReceiver(ActivityThread.java:2579)
04-12 18:21:40.153: E/AndroidRuntime(27924):    ... 9 more

The ContactData class:

public class ContactData {
    private String contact_name;
    private String ph_no;
    private String time_call;

    public ContactData(String contact_name, String ph_no, String time_call) {
        this.contact_name = contact_name;
        this.ph_no = ph_no;
        this.time_call = time_call;
    }

    public ContactData(String contact_name, String ph_no) {
        this.contact_name = contact_name;
        this.ph_no = ph_no;
    }

    public String getContactNo() {
        return this.ph_no;
    }
}

Froyo · Accepted Answer · 2015-04-12 13:37:20Z

3

try this

if (contactData.getContactNo() != null && !contactDate.getContactNo().isEmpty()) {
    // your code here
}

It seems that contactData.getContactNo() is returning null.

answered Apr 12, 2015 at 13:37

Froyo

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7 Comments

Psypher Over a year ago

How can it be null.. I am passing new ContactData("", number, date) to the method.

Stephen C Over a year ago

Yes ... but what does the call return? Is it returning the value of a variable that hasn't been initialized? What does the code say?

Blackbelt Over a year ago

at least two possibilities: 1. number is null when create the object. 2 your getter returns null

Froyo Over a year ago

@Ranjith you are getting null from your getter. You should elaborate more on ContactData class

Psypher Over a year ago

@Froyo Added the ContactData class

|

swiftBoy · Accepted Answer · 2015-10-10 08:38:18Z

0

Don't try to invoke methods on instance without making sure that it is not null. In your case contactData.getContactNo is null and when you are trying to invoke equals method on it NPE is thrown. There are two ways of avoiding it. First one is to compare the empty string with contactData.getContactNo else make sure that contactData and contact.getContactNo is not null.

Eg:

"".equals(contactData.getContactNo)

or

if(contactData != null && contactData.getContactNo != null)

edited Oct 10, 2015 at 8:38

swiftBoy

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answered Oct 10, 2015 at 8:18

Samuel Sunny Wilson

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