学习java第25天

1.java冒泡排序

public class BubbleSort {

    public static void main(String[] args) {
        int a[] = { 2, 3, 6, 4, 0, 1, 7, 8, 5, 9 };
        bubbleSort(a);
    }
    public static void toString(int[] a) {
        for (int i = 0; i < a.length; i++) {
            System.out.println(a[i]);
        }
    }
    private static void bubbleSort(int[] a) {
        int length = a.length;
        int temp = 0;
        for (int j = 0; j < a.length - 1; j++) {
            for (int i = 0; i < a.length - 1 - j; i++) {
                if (a[i] > a[i + 1]) {
                    temp = a[i + 1];
                    a[i + 1] = a[i];
                    a[i] = temp;
                }
            }
        }
        toString(a);
    }
}

2.java选择排序

public class SortDemo {

 

    public static void main(String[] args) {

        int[] arr = new int[] { 5, 3, 6, 2, 10, 2, 1 };

        selectSort(arr);

        for (int i = 0; i < arr.length; i++) {

            System.out.print(arr[i] + " ");

        }

    }

 

    public static void selectSort(int[] arr) {

        for (int i = 0; i < arr.length - 1; i++) {

            int minIndex = i; 

            for (int j = i + 1; j < arr.length; j++) {

                if (arr[j] < arr[minIndex]) {

                    minIndex = j; 

                }

            }      

            if (i != minIndex) {

                int temp = arr[i];

                arr[i] = arr[minIndex];

                arr[minIndex] = temp;

            }         

        }

    }

 

}

 

3.java插入排序

 

public class CRPX {
    public static void main(String[] s) {
        int[] a = {1,2,3,0};
        insertSort(a,0,a.length);
         for(int n : a){
                System.out.print(n+" ");
            }
    }
    public static void insertSort(int[] object,int low,int high) {
        for(int i = 1;i<high;i++) {
            if(object[i] < object[i-1]) {
                int temp = object[i];
                int j = i-1;
                for(;j >=low&&object[j] > temp;j--) {
                    object[j+1] = object[j];
                }
                object[j+1] = temp;
            }
        }
    }
}

4.java快速排序

package quickSort;
public class QuickSort {
private static int count;
public static void main(String[] args) {
int[] num = {7,4,1,8,5,2,9,6,3,10};
System.out.println(arrayToString(num,"未排序"));
QuickSort(num,0,num.length-1);
System.out.println(arrayToString(num,"排序"));
System.out.println("数组个数："+num.length);
System.out.println("循环次数："+count);
}
private static void QuickSort(int[] num, int left, int right) {
if(left>=right) {
return;
}
int key=num[left];
int i=left;
int j=right;
while(i<j){
while(num[j]>=key && i<j){
j--;
}
while(num[i]<=key && i<j){
i++;
}
if(i<j){
int temp=num[i];
num[i]=num[j];
num[j]=temp;
}
}
num[left]=num[i];
num[i]=key;
count++;
QuickSort(num,left,i-1);
QuickSort(num,i+1,right);
}
private static String arrayToString(int[] arr,String flag) {
String str = "数组为("+flag+")：";
for(int a : arr) 
str += a + " ";
}
return str;
}
}

5.明天学习内容：

程序的异常