int类型在接收null会报错，需要使用Java包装类型Integer，且Integer不能equal String字符串
package com.example.core.mydemo.json2;
/**
* int类型在接收null会报错，需要使用Java包装类型Integer
*/
public class IntegerNullTest {
public static void main(String[] args) {
Integer aaa = null;
//output: total=100
System.out.println("total=" + calc(aaa));
//Exception in thread "main" java.lang.NullPointerException
// at com.example.core.mydemo.json2.IntegerNullTest.main(IntegerNullTest.java:10)
// System.out.println("total2=" + calc2(aaa));
//unsame 字符串与Integer比较，JAVA规范错误写法
Integer bbb = 100;
if("100".equals(bbb)){
System.out.println("same");
}else{
System.out.println("unsame");
}
}
private static Integer calc(Integer aaa) {
return 100;
}
/**
* int类型在接收null会报错
* @param aaa
* @return
*/
private static Integer calc2(int aaa) {
return 100;
}
}
