【发布时间】：2015-10-28 19:08:01
【问题描述】：
import javax.swing.*;
import java.lang.reflect.Array;
import java.util.Collections;
import java.util.Random;
import java.util.Scanner;
public class RandExample {
public static void main(String[] args) {
int MethodChoice = Integer.parseInt(JOptionPane.showInputDialog("What method would you like to use to sort the random numbers" + "\n" + "1 - Selection Sort" + "\n" + "2 - Bubble Sort" + "\n" + "3 - Insertion Sort" + "\n" + "4 - Quick Sort"));
if (MethodChoice == 1) {
int iTotalCount = Integer.parseInt(JOptionPane.showInputDialog("What is the total number of integers?"));
int SortOrder = Integer.parseInt(JOptionPane.showInputDialog("1 - Ascending "
+ "2 - Descending"));
if (SortOrder == 2) {
int[] array = new int[iTotalCount];
System.out.println("After sorting using the Selection Sort, " + "Using Descending Order" + "the array is: ");
for(int count = array.length-1; count >= 0; count--)
System.out.print(array[count] + " ");
selectionSortReverse(array);
}
int[] array = new int[iTotalCount];
Random randomGenerator = new Random();
for (int i = 0; i < iTotalCount; i++) {
array[i] = randomGenerator.nextInt(1001);
System.out.print(" " + array[i]);
}
System.out.println("\n---------------------------------");
selectionSort(array);
//print out sorted list
System.out.println("After sorting using the Selection Sort," + " the array is:");
for (int count = 0; count < array.length; count++) {
System.out.print(array[count] + " ");
}
}
我有一个子程序调用 selectionSortReverse(array);当用户选择 2 使其按降序排序时，但当我点击 2 并继续时，它会按升序发布数字。我把它放错地方了吗？这是我的 selectionSortReverse 子例程：
public static void selectionSortReverse(int data[]) {
int smallest;
for (int i = 0; i < data.length - 1; i++) {
smallest = i;
//see if there is a smaller number further in the array
for (int index = i + 1; index < data.length; index++) {
if (data[index] > data[smallest]) {
swap(data, smallest, index);
}
}
}
}
使用 cricket_007 的建议更新代码
import javax.swing.*;
import java.lang.reflect.Array;
import java.util.Collections;
import java.util.Random;
public class RandExample {
private static int[] generateRandomArray(int size, int randomMax) {
int[] array = new int[size];
Random randomGenerator = new Random();
for (int i = 0; i < size; i++) {
array[i] = randomGenerator.nextInt(randomMax);
}
return array;
}
public static void main(String[] args) {
int MethodChoice = Integer.parseInt(JOptionPane.showInputDialog("What method would you like to use to sort the random numbers" + "\n" + "1 - Selection Sort" + "\n" + "2 - Bubble Sort" + "\n" + "3 - Insertion Sort" + "\n" + "4 - Quick Sort"));
if (MethodChoice == 1) {
int iTotalCount = Integer.parseInt(JOptionPane.showInputDialog("What is the total number of integers?"));
int SortOrder = Integer.parseInt(JOptionPane.showInputDialog("1 - Ascending "
+ "2 - Descending"));
if (SortOrder == 2) {
int[] array = generateRandomArray(iTotalCount, 1001);
selectionSortReverse(array);
for(int count = array.length-1; count >= 0; count--)
System.out.print(array[count] + " ");
System.out.println("\n---------------------------------");
System.out.println("After sorting using the Selection Sort, " + "Using Descending Order" + " " + "the array is: ");
for(int i : array) {
System.out.print(i + " ");
}
} else if (SortOrder == 1) {
int[] array = generateRandomArray(iTotalCount, 1001);
selectionSort(array);
for(int count = array.length-1; count >= 0; count--)
System.out.print(array[count] + " ");
System.out.println("\n---------------------------------");
System.out.println("After sorting using the Selection Sort," + " the array is:");
for(int i : array) {
System.out.print(i + " ");
}
}
更新 3
代码适用于选择 ---> 气泡，插入不多。随机整数的打印与排序列表的格式相同。
代码如下：
} else if (MethodChoice == 3) {
if (SortOrder == 2) {
insertionSortReverse(array);
System.out.println("After sorting using the Insertion Sort, " + "Using Descending Order" + " " + "the array is: ");
} else if (SortOrder == 1) {
insertionSort(array);
System.out.println("After sorting using the Insertion Sort," + " the array is:");
}
for (int i : array) {
System.out.print(i + " ");
}
}
这是我的插入排序（）和插入排序反向（）子：
public static void insertionSort(int data[]) {
int insert;
for (int next = 1; next < data.length; next++) {
insert = data[next];
int moveItem = next;
while (moveItem > 0 && data[moveItem - 1] > insert) {
data[moveItem] = data[moveItem - 1];
moveItem--;
}
data[moveItem] = insert;
}
}
public static void insertionSortReverse(int data[]) {
int insert;
for (int next = 1; next < data.length; next++) {
insert = data[next];
int moveItem = next;
while (moveItem < 0 && data[moveItem - 1] < insert) {
data[moveItem] = data[moveItem - 1];
moveItem--;
}
data[moveItem] = insert;
}
}
【问题讨论】：
-
这就是为什么您不应该使用自己的比较功能，而应该使用比较器。如果你是，你可以使用 reverseOrder(): docs.oracle.com/javase/8/docs/api/java/util/…
-
@ControlAltDel - 假设这是 Java8
-
我刚刚发现调用新的子程序似乎要容易得多。我有一种感觉，当他们选择他们想要的顺序时，它可能与 if 语句有关。也许它只是继续回到常规代码而不是我放在 if 代码块中的代码？ @ControlAltDel