Android ArrayList Strange Null Pointer Exception

Question

I have problem with this code:

 for(int i2=0;i2<ftdata.size();i2++){
        System.out.println("FTDATASIZE: " +ftdata.get(i2)); // here pass and shows null
        String test=ftdata.get(i2); // here gets Null Pointer Exception ????
        if(test.equals("null")){

        }
    }

System.out shows in LogCat "FTDATASIZE: null" but I get error with this line "String test=ftdata.get(i2);" I dont get it? why I get Null Pointer Exception?

    04-07 05:42:36.309: I/System.out(12983): STDATASIZE: 1
    04-07 05:42:36.309: I/System.out(12983): FTDATASIZE: 1
    04-07 05:42:36.309: I/System.out(12983): FTDATASIZE: null
    04-07 05:42:36.309: W/dalvikvm(12983): threadid=10: thread exiting with uncaught exception (group=0x40166560)
    04-07 05:42:36.309: E/AndroidRuntime(12983): FATAL EXCEPTION: Thread-11
    04-07 05:42:36.309: E/AndroidRuntime(12983): java.lang.NullPointerException
    04-07 05:42:36.309: E/AndroidRuntime(12983):    at soft.ProDb.distanceRunsMonthly(ProDb.java:22718)
    04-07 05:42:36.309: E/AndroidRuntime(12983):    at soft.ProDb.runsMonthly(ProDb.java:22593)
    04-07 05:42:36.309: E/AndroidRuntime(12983):    at soft.SHtmlM.exportALLHtml(StringaHtmlM.java:111)
    04-07 05:42:36.309: E/AndroidRuntime(12983):    at soft.ProDb$1.run(ProDb.java:12714)
    04-07 05:42:36.309: E/AndroidRuntime(12983):    at java.lang.Thread.run(Thread.java:1019)

OK Fixed

this works for me

 if(ftdata.size()==1&& ftdata.get(0)==null){
        ftdata=stdata;
    }

Just wanted to test if ftdata.get(0) is null or not

ftdata.get(i2) is null and cann't to pass the null value to the string??? — John BG
– John BG, Commented Apr 7, 2013 at 2:56
and this is not Android "04-07 05:42:36.309: E/AndroidRuntime(12983):" ?! — John BG
– John BG, Commented Apr 7, 2013 at 3:07

Karakuri · Accepted Answer · 2013-04-07 03:00:01Z

4

The null pointer is on the line if(test.equals("null")){ because test is null and you are trying to call .equals() on it.

If you are trying to check that the String is null, use if (test == null) instead

If you are trying to check that the String has the value "null", use if ("null".equals(test)) instead

answered Apr 7, 2013 at 3:00

Karakuri

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1 Comment

John BG Over a year ago

you are right! but how can I to pass the null value to string so that test="null" ? must wait 5min to accept

Masoud Kardani · Accepted Answer · 2013-04-07 03:01:52Z

1

try this:

for(int i2=0;i2<ftdata.size();i2++){
        System.out.println("FTDATASIZE: " +ftdata.get(i2));
        String test; 
        if(ftdata.get(i2)!=null){
            test = ftdata.get(i2);
        }
    }

answered Apr 7, 2013 at 3:01

Masoud Kardani

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