Java入门实验求助：用do-while与随机数模拟掷骰子统计对子次数

Let’s walk through the issues in your code and get it working properly for simulating 10,000 dice rolls and counting matching pairs:

Key Issues in Your Original Code #

• Incorrect Random Number Generation: Your current code (int)(Math.random()*6)-1 produces numbers from -1 to 4—not the 1-6 range we need for dice. Plus, the task specifies using a Random object instead of Math.random().
• Broken Loop Control: The loop condition x > 10000 will never trigger (since x starts at 0), and you never increment x inside the loop, so even if the condition was right, it would run infinitely.
• Unreachable Pair Checks: Since your dice values are wrong, the checks for 1-6 pairs will never hit correctly.

Corrected Code #

import java.util.Random;

public class DiceRoll {
    public static void main(String []args){
        int rollCount = 0;
        int counter1 = 0;
        int counter2 = 0;
        int counter3 = 0;
        int counter4 = 0;
        int counter5 = 0;
        int counter6 = 0;
        
        // Initialize Random object as required
        Random random = new Random();
        
        do {
            // Generate 1-6 using Random's nextInt method (nextInt(6) gives 0-5, add 1 to shift to 1-6)
            int dice1 = random.nextInt(6) + 1;
            int dice2 = random.nextInt(6) + 1;
            
            if (dice1 == dice2) {
                // Use switch for cleaner pair checking (if statements work too, switch is more concise)
                switch(dice1) {
                    case 1: counter1++; break;
                    case 2: counter2++; break;
                    case 3: counter3++; break;
                    case 4: counter4++; break;
                    case 5: counter5++; break;
                    case 6: counter6++; break;
                }
            }
            
            // Increment our roll counter each iteration
            rollCount++;
        } while (rollCount < 10000); // Run until we've done 10,000 rolls
        
        System.out.println("Results of 10,000 dice roll simulations:");
        System.out.println("1-1 pairs: " + counter1);
        System.out.println("2-2 pairs: " + counter2);
        System.out.println("3-3 pairs: " + counter3);
        System.out.println("4-4 pairs: " + counter4);
        System.out.println("5-5 pairs: " + counter5);
        System.out.println("6-6 pairs: " + counter6);
    }
}

What Changed? #

1. Added Random Object: We use Random random = new Random() and random.nextInt(6) + 1 to generate proper 1-6 values—this aligns with the task's requirement.
2. Fixed Loop Logic: Renamed x to rollCount for clarity, increment it each loop, and use rollCount < 10000 as the condition to run exactly 10,000 times.
3. Cleaned Up Pair Checking: Switched to a switch statement for more readable pair counting (your original if statements would work too if the dice values were fixed, but switch is neater here).
4. Fixed Dice Value Range: random.nextInt(6) gives 0-5, adding 1 shifts it to the correct 1-6 range for standard dice.

When you run this, you’ll see each pair count is roughly around 1/36 of 10,000 (about 277) since each pair has a 1/36 probability of occurring—this makes sense statistically!

内容的提问来源于stack exchange，提问作者Luke Auslender