java - How search a datum in ArrayList<StringBuilder> with indexOf -

how search datum in arraylist indexof

arraylist<stringbuilder> state = new arraylist<stringbuilder>(); state.add(new stringbuilder("a")); state.add(new stringbuilder("b")); state.add(new stringbuilder("c")); state.add(new stringbuilder("d")); system.out.println(state.indexof(new stringbuilder("b"))); //out: -1 

you using arraylist of stringbuilderobjects.

as stringbuilder used building strings, , not strings , can't use indexof(s), whole object should equal 1 comparing returns true.

in order solve problem, should build string want stringbuilder, , make arraylist of already-built strings only, this:

arraylist<string> state = new arraylist<string>(); stringbuilder = new stringbuilder("a") //do whatever want state.add(a.tostring()); state.add(b.tostring()); state.add(c.tostring()); state.add(d.tostring()); ..... system.out.println(state.indexof("b")); //out: 1