package com.isea.java;
public class Test {
    public static void main(String[] args) {
        String str = "123";
        Integer num1 = new Integer(str);
        int num2 = Integer.parseInt(str);
        Integer num3 = Integer.valueOf(str);
        System.out.println(num1 + "\t" + num2 + "\t" + num3);//123	123	123
    }
}