Java - 随机 nextInt 方法返回相同的整数

Question

我有一些我正在处理的代码。我被困在涉及随机 nextInt(( 方法的一部分上。我遇到的这个问题是我的代码从我的数组索引返回完全相同的随机整数。我打算做的是遍历一个 for 循环，对于我的 16 次迭代中的每一次，我希望让 Random nextInt(( 方法通过索引从数组中选择一个字符串并将其打印到屏幕上。 目前，我能够从每个索引生成 1 个随机字符串。在接下来的 15 次迭代中，我的代码打印相同的随机选择，而不是随机选择一个新的。

import java.awt.Color;
import java.util.*;
import java.util.Random;
class Main {
private int numStrings = 6; 
private double guitarLength = 28.2;
private String guitarManufacturer = "Gibson";
private Color guitarColor = Color.RED; 
private int musicLength = 16;
private static int i = 1;
private static Random rand = new Random();
public Main (){
this.numStrings = numStrings; 
this.guitarLength = guitarLength;
this.guitarManufacturer = guitarManufacturer;
this.guitarColor = guitarColor;
}
public Main (int strings, double length, String manufacturer, Color color){
numStrings = strings;
guitarLength = length;
guitarManufacturer = manufacturer;
guitarColor = color;
System.out.printf("%d, %f, %s, %s", numStrings, guitarLength, guitarManufacturer, guitarColor + "n");
}
public int getNumStrings() {
return this.numStrings;
}
public double getGuitarLength() {
return this.guitarLength;
}
public String getGuitarManufacturer() {
return this.guitarManufacturer;
}
public Color getGuitarColor(){
return this.guitarColor;
}
public static void playGuitar(){
String[] musicNotes = {"A", "B", "C", "D", "E", "F", "G"};
String[] musicDuration = {"(0.25)","(0.5)","(1)", "(2)","(4)"};
int index1 = rand.nextInt(musicNotes.length);
int index2 =  rand.nextInt(musicDuration.length);
for (i = 1; i < 17; i++){
System.out.print(musicNotes[index1]);
System.out.print(musicDuration[index2] + ",");
}
}
public static void main (String args[] ){
Main newGuitar = new Main(6, 24.75, "Les Paul", Color.white);
playGuitar();
}
}

Answer 1

你只生成两个随机数(index1和index2(，然后在循环中多次使用它们。

您应该为循环的每次迭代生成新的随机数：

for (i = 1; i < 17; i++) {
int index1 = rand.nextInt(musicNotes.length);
int index2 =  rand.nextInt(musicDuration.length);
System.out.print(musicNotes[index1]);
System.out.print(musicDuration[index2] + ",");
}

Answer 2

您在循环开始之前调用rand.nextInts，因此它们的值在整个循环中是相同的。您需要在循环内移动这两行。