java - JUnit testing for assertEqual NullPointerException -

i not sure why test case doesn't have output of true. both cases should give nullpointerexception.

i've tried doing (not same gives , output of true) :

    string nullstr = null;  //@test public int nulloutput1() {     nullstr.indexof(3);     return 0; }  //@test(expected=nullpointerexception.class) public int nulloutput2() {     nullstr.indexof(2);     return 0; }  @test(expected=nullpointerexception.class) public void testboth() {     assertequals(nulloutput1(), nulloutput2()); } 

runner:

import org.junit.runner.junitcore; import org.junit.runner.result; import org.junit.runner.notification.failure;  public class testrunnerstringmethods {     public static void main(string[] args) {         result result = junitcore.runclasses(testjunitmyindexof.class);         (failure failure : result.getfailures()) {             system.out.println(failure.tostring());         }         system.out.println(result.wassuccessful());     } } 

method:

public static int myindexof(char[] str, int ch, int index) {         if (str == null) {             throw new nullpointerexception();         }         // increase efficiency         if (str.length <= index || index < 0) {             return -1;         }         (int = index; < str.length; i++) {             if (index == str[i]) {                 return i;             }         }         // if not found         return -1;     } 

test case:

@test(expected=nullpointerexception.class) public void testnullinput() {     assertequals(nullstring.indexof(3), stringmethods.myindexof(null, 'd',3)); } 

i believe want use fail here:

@test(expected=nullpointerexception.class) public void testnullinput() {     fail(nullstring.indexof(3)); } 

make sure add import static org.junit.assert.fail; if need to.