字符串HashCode的计算

public class Demo{
    public static void main(String[] args){
        String str = "我是一个学Java的小菜鸟";
        char[] chars = str.toCharArray();
        int hashcode = 0;
        if(hashcode == 0 && chars.length > 0 ){
            for (int i = 0; i < chars.length; i++) {
                hashcode = 31 * hashcode + chars[i];
            }
        }
        System.out.println("最终hashcode值是:"+hashcode);
    }
}