Java - Adding Elements to Array of Hashmaps Produces Null Error -


this question has answer here:

i trying create 2d array of hashmaps. following code:

   @suppresswarnings("unchecked")     map<string, boolean>[][] arrayblock3 = (map <string, boolean>[][]) new map[6][6];

when try add elements array however, @ runtime there null pointer exception @ first line adding element array.

the code add element is:

    arrayblock3[0][0].put("b", false);     arrayblock3[0][1].put("g", false);     arrayblock3[0][2].put("b", false);     arrayblock3[0][3].put("b", false);     arrayblock3[0][4].put("g", false);     arrayblock3[0][5].put("b", false);

error message

exception in thread "main" java.lang.nullpointerexception @ main.main(main.java:20)

i appreciate help, thanks.

you need initialize each element in matrix of map (and need use class implements map, such hashmap):

for (int = 0; < arrayblock3.length; i++) {     (int j = 0; j < arrayblock3[i].length; j++) {         arrayblock3[i][j] = new hashmap<>();     } }

Comments

Post a Comment

Popular posts from this blog

PHP and MySQL WP -

i trying accomplish 2 things here code. writing php directly wp page using insert php plugin. 1) query mysql database , return results 1 column 4 columns. 2) make each result own hyperlink directs user new wp page runs new query on page. i able query show results , turn results dynamic hyperlink, cannot formatting down. right returns result 1 column. here have: [insert_php] $servername = "localhost"; $username = "login"; //edited privacy $password = "password"; //edited privacy $database = "database"; //edited privacy // create connection $conn = new mysqli($servername, $username, $password, $database); // check connection if ($conn->connect_error) { die("connection failed: " . $conn->connect_error); } echo "connected successfully"; //get results database $result = mysqli_query($conn,"select mine mines order mine"); $all_property = array(); //declare array saving property //showing proper...
Read more

android - InAppBilling registering BroadcastReceiver in AndroidManifest -

i'm implementing inapp billing in android app. works well, however, i'm trying decouple broadcast receiver activity manifest. suggestion in android's trivialdrive sample: // important: dynamically register broadcast messages updated purchases. // register receiver here instead of <receiver> in manifest // because call getpurchases() @ startup, therefore can ignore // broadcasts sent while app isn't running. // note: registering listener in activity bad idea, done here // because sample. regardless, receiver must registered after // iabhelper setup, before first call getpurchases(). currently there's class extends broadcastreceiver : public class iabbroadcastreceiver extends broadcastreceiver { /** * intent action receiver should filter for. */ public static final string action = "com.android.vending.billing.purchases_updated"; private final iabbroadcastlistener mlistener; public iabbroadcastreceiver(iabbroadcastlistener listener) { m...
Read more

go - golang pprof for c library code -

i have been trying profile golang application pprof, seems details of c code(linked static library) missed in output result. flame graph from frame graph can see c code time consuming reported within "runtime._externalcode", no details @ all. , sure static library compiled debug enable. so there way make pprof details(like stack trace) of 3rd party c code? or there other golang profiling tool this?
Read more