Java Compare 2 integers with equals or ==?

问题:

i am very very new to Java and i would like to know how can i compare 2 integers? I know == gets the job done.. but what about equals? Can this compare 2 integers? (when i say integers i mean "int" not "Integer"). My code is:

import java.lang.*;
import java.util.Scanner;
//i read 2 integers the first_int and second_int
//Code above
if(first_int.equals(second_int)){
//do smth
}
//Other Code

but for some reason this does not work.. i mean the Netbeans gives me an error: "int cannot be dereferenced" Why?

回答1:

int is a primitive. You can use the wrapper Integer like

Integer first_int = 1;
Integer second_int = 1;
if(first_int.equals(second_int)){ // <-- Integer is a wrapper.

or you can compare by value (since it is a primitive type) like

int first_int = 1;
int second_int = 1;
if(first_int == second_int){ // <-- int is a primitive.

JLS-4.1. The Kinds of Types and Values says (in part)

There are two kinds of types in the Java programming language: primitive types (§4.2) and reference types (§4.3). There are, correspondingly, two kinds of data values that can be stored in variables, passed as arguments, returned by methods, and operated on: primitive values (§4.2) and reference values (§4.3).

回答2:

If you want to compare between

1-two integer 
If(5==5)
2- char
If('m'=='M')
3 string
String word="word"
word.equals("word")

回答3:

As int is primitive you can not use equals. What you can do Use Interger as wrapper

 void IntEquals(Integer original, Integer reverse) {
        Integer origianlNumber = original;
        Integer reverseNumber = reverse;

        if (origianlNumber.equals(reverse)) {
            System.out.println("Equals ");
        } else {
            System.out.println("Not Equal");
        }