1.取[0-n]的n个随机数存入数组中，要求数据不能重复.

import java.util.Random;
import java.util.Scanner;

public class lx {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
System.out.println("请输入n,将生成n个随机数存入数组array[n]");
int n = sc.nextInt();
int a[] = new int[n];
suiJi(a, n);
}

public static void suiJi(int a[], int n) {
    Random r = new Random();
    for (int i = 0; i < n; i++) {
        int number = r.nextInt(n);
        boolean s;
        do {
            s = false;
            for (int j = 0; j < i; j++) {
                if (number == a[j]) {
                    number = r.nextInt(n);
                    s = true;
                    break;
                }
            }
        } while (s);
        a[i] = number;
    }
    for (int j = 0; j < n; j++) {
        System.out.println(a[j]);
    }
}

}

2. 设计一个方法，将数组中的数据打乱顺序

import java.util.Random;

public class lx {
public static void main(String[] args) {
int n = 10;
int a[] = disorder(n);
for (int i = 0; i < n; i++) {
System.out.println(a[i]);
}

}

public static int[] disorder(int n) {
    Random r = new Random();
    int a[] = new int[n];
    for (int i = 0; i < n; i++) {
        a[i] = i;
    }
    for (int i = 0; i < n / 2; i++) {
        int number = r.nextInt(n);
        int temp = a[i];
        a[i] = a[number];
        a[number] = temp;
    }
    return a;
}

}

3.去除数组{1,3,1,4,2,3,6,1,5}中的重复项,存入一个新的数组,并从大到小排序.

public class lx {
public static void main(String[] args) {
int arr[] = { 1, 3, 1, 4, 2, 3, 6, 1, 5 };

    int number = 0;
    int count = 0;

            //大到小排序
    for (int i = 0; i < arr.length - 1; i++) {
        for (int j = 1; j < arr.length - i; j++) {
            int temp = 0;
            if (arr[j] > arr[j - 1]) {
                temp = arr[j];
                arr[j] = arr[j - 1];
                arr[j - 1] = temp;
            }
        }

    }
            //去重，重复的赋值为-1，做计数
    for (int i = 0; i < arr.length; i++) {
        number = arr[i];
        boolean s = true;
        for (int j = 0; j < i; j++) {
            if (number == arr[j]) {
                count++;
                s = false;
            }
        }
        if (!s) {
            arr[i] = -1;
        } else {
            arr[i] = number;
        }
    }
            //定义新数组刨去值为-1的
    int b[] = new int[arr.length - count];
    int j = 0;
    for (int i = 0; i < arr.length; i++) {
        if (arr[i] != -1) {
            b[j] = arr[i];
            j++;
        }
    }
    for (int i = 0; i < b.length; i++) {
        System.out.println(b[i]);
    }

}

}

4.给定一个含有n个元素的整型数组a 例如{1,1,1,2,4,3,3} ，如果某些元素出现的次数为奇数次，则将其输出:例如1,2,4

public class lx {
public static void main(String[] args) {
int a[] = { 1, 1, 1, 2, 4, 3, 3 };
int c[] = new int[a.length];
int number = 0;
int count = 0;
for (int q = 0; q < a.length; q++) {
c[q] = a[q];
// System.out.println(c[q]);
}

    for (int i = 0; i < a.length; i++) {
        boolean s = true;
        number = a[i];

        for (int j = 0; j < i; j++) {
            if (number == a[j])
                s = false;

        }
        if (!s) {
            count++;
            a[i] = -1;
        } else {
            a[i] = number;
        }
    }
    int b[] = new int[a.length - count];
    int count1 = 0;
    for (int k = 0; k < a.length; k++) {
        if (a[k] != -1) {
            b[count1] = a[k];
            count1++;
        }
    }

    for (int m = 0; m < b.length; m++) {
        number = b[m];
        int count2 = 0;
        for (int n = 0; n < c.length; n++) {
            if (number == c[n])
                count2++;
        }
        if (count2 % 2 != 0) {
            System.out.println(b[m]);
        }
    }

}

}