Method Does Not Exist Or Incorrect Signature

How to resolve the method does not exist or incorrect signature salesforce?

 I have a code as below

public class TestClass { 

Public TestClass { } 

public long[] callerSub(string keya, String keyb){ 

long[] datalr = new long[] {0,0}; 

datalr[0] = 5; 

datalr[1] = 7; 

return datalr; } } which is showing the error method does not exist or incorrect signature can anyone help me please