如何使用隨機數發生器與if語句

Question

所以我正在製作一個基於文本的遊戲，並且我想使用一個隨機數生成器來說明它生成的隨機數是3，它會說某個確定的怪物出現了。由於某些原因，它無法讓我爲隨機數做if語句。以下是代碼：

import java.util.Random; 
import java.util.Scanner; 
public class mainClass 
{ 
    public static void main(String args[]) 
    { 
     Scanner input = new Scanner(System.in); 

     String username, character_type, testing_enemy; 

     //Variables for spells 
     double mage_fire, mage_iceblast, mage_voidray; 
     double warrior_uppercut, warrior_kick, warrior_hook; 
     double archer_diamond, archer_power, archer_precision; 

     //variables for base stats 
     int base_health, base_spell_dmg, base_attack_dmg, base_mana; 

     //variable for random number generator 
     int number = Integer.parseInt(testing_enemy); 

     System.out.println("Welcome to Realm Of Worlds!"); 
     System.out.println("Enter username: "); 
     username = input.nextLine(); 
     System.out.println(); 
     System.out.println("Welcome to Realm Of Worlds " + username); 
     System.out.println("Realm Of Worlds is an interactive text based game " 
       + "that allows you to fight monsters and buy items and spells to get even stronger."); 
     System.out.println("Would you like to be a Mage, a Warrior, or an Archer?"); 
     character_type = input.nextLine(); 


     if(character_type.equals("mage") || character_type.equals("Mage")) 
     { 
      System.out.println("Ok, " + username + " you are now a " + character_type + "!"); 

      base_health = 850; 
      base_spell_dmg = 60; 
      base_attack_dmg = 50; 
      base_mana = 500; 

      System.out.println("As a Mage, you have " + base_health + " base health, " + base_spell_dmg + " base spell damage, " + base_attack_dmg + " base attack damage, and " + base_mana + " base mana."); 
      System.out.println("Your spells are Fire Blast, Ice Blast, and Void Ray."); 
      System.out.println("All of your spells do Spell Damage, so focus on building Spell Damage Items"); 

      mage_fire = (30 + (.60*base_spell_dmg)); 
      mage_iceblast = (50 + (.45*base_spell_dmg)); 
      mage_voidray = (45 + (.55*base_spell_dmg)); 

      System.out.println("Would you like to use 1. Fire Blast, 2. Ice Blast, 3. Void Ray? (Just type 1, 2, or 3)"); 

     } 


     if(character_type.equals("warrior") || character_type.equals("Warrior")) 
     { 
      System.out.println("Ok, " + username + " you are now a " + character_type + "!"); 

      base_health = 1000; 
      base_spell_dmg = 20; 
      base_attack_dmg = 80; 
      base_mana = 300; 

      System.out.println("As a Warrior, you have " + base_health + " base health, " + base_spell_dmg + " base spell damage, " + base_attack_dmg + " base attack damage, and " + base_mana + " base mana."); 
      System.out.println("Your spells are Uppercut, Kick, and Hook Punch"); 
      System.out.println("All of your spells do Attack Damage, so focus on building Attack Damage Items"); 

      warrior_uppercut = (30 + (.55*base_attack_dmg)); 
      warrior_kick = (50 + (.45*base_attack_dmg)); 
      warrior_hook = (45 + (.50*base_attack_dmg)); 
     } 

     if(character_type.equals("archer") || character_type.equals("Archer")) 
     { 
      System.out.println("Ok, " + username + " you are now a " + character_type + "!"); 

      base_health = 700; 
      base_spell_dmg = 40; 
      base_attack_dmg = 70; 
      base_mana = 400; 

      System.out.println("As an Archer, you have " + base_health + " base health, " + base_spell_dmg + " base spell damage, " + base_attack_dmg + " base attack damage, and " + base_mana + " base mana."); 
      System.out.println("Your spells are Diamond Arrow, Power Shot, and Precision Eye"); 
      System.out.println("Also, as archer, you have a passive ability of dodging 1 in every 6 attacks from an opponent"); 
      System.out.println("Your spells do a combination of Spell and Attack Damaeg, so it is worth building both types of items, but more Attack Damage is done than Spell Damage"); 

      archer_diamond = (30 + ((.35*base_attack_dmg)+(.20*base_spell_dmg))); 
      archer_power = (50 + ((.30*base_attack_dmg)+(.15*base_spell_dmg))); 
      archer_precision = (45 + ((.35*base_attack_dmg)+(.15*base_spell_dmg))); 
     } 

     //Setting up enemy randomization 
     **Random dice = new Random(); 

     for(int counter=1; counter<=3; counter++) 
     { 
      number = 1+dice.nextInt(3); 

      if(number.equals(3)) 
      { 
       System.out.println("A monster appeared!!"); 
      }** 
     } 
    } 
} 

Answer 1

您正在使用等於接受對象。但是int不是對象。嘗試==代替。

if (number == 3) 

Answer 2

嘗試if (number == 3)而不是if (number.equals(3))。通常，var.equals()用於對象和字符串。比較數值（整數和浮點數）可以用==來完成。

Answer 3

讓我們舉個例子。

假設我希望生成5-10之間的數字。

int max=10; 
    int min=5; 
    int diff=max-min; 
    Random rn = new Random(); 
    int i = rn.nextInt(diff+1); 
    i+=min; 
    System.out.print("The Random Number is " + i); 

可以明白這一點

nitialize最大與最高值和最低值最小。

現在，我們需要確定可以獲得多少個可能的值。對於這個例子，這將是

5, 6, 7, 8, 9, 10 

所以，這個計數將是最大最小+ 1。

i.e. 10-5+1=6 

該隨機數將產生一個0-5之間的數字。

i.e. 0, 1, 2, 3, 4, 5 

添加min值到隨機數將產生

5, 6, 7, 8, 9, 10 

因此，我們得到所需要的範圍內。