Java 數組中元素的比較問題！该怎么处理

String xx = "a-b-c";
        String[] testStrings = xx.split("-");
        
        System.out.println(testStrings[0]);
        
        if(testStrings[0].toString() == "a"){
            System.out.println("00000");
        }else if(testStrings[0].equals("a")){
            System.out.println("ssssss");
        }
        else{
            System.out.println("11111");
        }