大家好，小弟剛開始自學java卡這個問題好幾天了...
這段是參考"java se7 技術手冊"後面的習題答案，
看了很久一直不懂在產生"亂數"(8~16行)後之後x[i]的值會剛好是1~52的數序，
而不會因為新的亂數造成重覆值的發生呢??麻煩大家可以為小弟解惑，謝謝^^
public class s0402 {
public static void main(String[] args ) {
final int N = 52;
int[] x = new int[N + 1];
for(int i =1; i <= N; i++) {
x[i] = i;
}
for(int i = 1; i <= N; i++) {
int j = (int) (Math.random()*N);
if(j == 0){
j = 1;
}
int tmp = x[i];
x[i] = x[j];
x[j] = tmp;
}
for(int i = 1; i <= N; i++) {
switch((x[i] - 1) / 13) {
case 0: System.out.print("梅"); break;
case 1: System.out.print("桃"); break;
case 2: System.out.print("磚"); break;
case 3: System.out.print("心");
}
int remin = x[i] % 13;
switch(remin) {
case 0: System.out.print(" K "); break;
case 12: System.out.print(" Q "); break;
case 11: System.out.print(" J "); break;
default: System.out.printf("%2d ",remin);
}
System.out.printf("%c",i % 13 == 0 ? '\n' : ' ' );
}
}
}