java - App crashing when chosing random numbers to select array index -

edit : solved. silly silly mistake! fast response. have 6 arrays each having 150-200 elements . when try select index numbers, first 2 selected jolly starting third index number, app begins crash. app had 1 activity.

string a[]={}; string b[]={}; ... @override protected void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);     setcontentview(r.layout.main); }  public void generate(view v) {     ttoast("insult on beep!");     gener(); }  public void gener() {      int i1 = new random().nextint(a.length);     string r1 = (a[i1]);      int i2 = new random().nextint(b.length);     string r2 = (a[i2]);      int i3 = new random().nextint(c.length);     string r3 = (a[i3]);      int i4 = new random().nextint(d.length);     string r4 = (a[i4]);      int i5 = new random().nextint(e.length);     string r5 = (a[i5]);      int i6 = new random().nextint(f.length);     string r6 = (a[i6]);      string fin = r1 + r2 +r3 + r4 +r5 +r6;     //works ok r2 r3 error occurs     final textview mtextview = (textview) findviewbyid(r.id.gen);     mtextview.settext(fin);     ttoast("me works"); } private void ttoast(string s) {     context context = getapplicationcontext();     int duration = toast.length_long;     toast toast = toast.maketext(context, s, duration);     toast.show(); } 

you calculating random index every array f trying value of index array. may cause arrayindex exception try change code this

     int i1 = new random().nextint(a.length);         string r1 = (a[i1]);          int i2 = new random().nextint(b.length);         string r2 = (b[i2]);          int i3 = new random().nextint(c.length);         string r3 = (c[i3]);          int i4 = new random().nextint(d.length);         string r4 = (d[i4]);          int i5 = new random().nextint(e.length);         string r5 = (e[i5]);          int i6 = new random().nextint(f.length);         string r6 = (f[i6]);          //remaining code....