How to avoid null insertion in ArrayList?

This question already has an answer here:

Avoiding != null statements 58 answers

---

Avoiding null can be harmful sometimes and it could hide possible bugs.

If you're worried about getting NullPointerException in some stage, you can simply check if the item stored in the ArrayList is null .

You cannot disallow inserting null to ArrayList .

---

You can try something like that, But if you want to do exactly what you are trying you have to rewrite add() in ArrayList class. Using this validation you can avoid null

public static void main(String[] args) {
    ArrayList<String> al=new ArrayList<String>();
    al=add(al,null);
    al=add(al,"Ramesh");
    al=add(al,"hi");
}

public static ArrayList<String> add(ArrayList<String> al,String str){
   if(str!=null){
      al.add(str);
      return al;
   }else {
      return al;
   }
}

In this case you have to call your custom add method to add element

---

ArrayList<String> al = new ArrayList<String>() {

            @Override
            public boolean add(String s ) {

                if( s != null ) {
                    return super.add( s );
                }
                return false;
            }
        };
al.add(null);
al.add("blabla");

链接地址: http://www.djcxy.com/p/13302.html

上一篇: 在java中检查空引用的乐观方式

下一篇: 如何避免在ArrayList中的空插入？