求两个数组得交集，并集，差集

public final class IntegerArrayUtil{
    // 私有构造函数，防止创建IntegerArrayUtil的实例
    private IntegerArrayUtil(){
       
    }
   
   
    public static int[] union(int[] arr1,int[] arr2){
        DynamicArray dynamicArray=new DynamicArray();
       
        for(int temp:arr1){
            dynamicArray.add(temp);
        }
       
        for(int temp:arr2){
            if(!exist(temp,arr1)){
                dynamicArray.add(temp);
            }
        }
       
        return dynamicArray.getArr();
    }
   
   
    public static int[] intersact(int[] arr1,int[] arr2){
        DynamicArray dynamicArray=new DynamicArray();
       
        for(int temp:arr1){
            if(exist(temp,arr2)){
                dynamicArray.add(temp);
            }
        }
       
        return dynamicArray.getArr();
    }
   
   
    public static int[] minus(int[] arr1,int[] arr2){
        DynamicArray dynamicArray=new DynamicArray();
       
        for(int temp:arr1){
            if(!exist(temp,arr2)){
                dynamicArray.add(temp);
            }
        }
       
        return dynamicArray.getArr();
    }
   
   
    private static boolean exist(int number,int[] arr){
        for(int temp:arr){
            if(number==temp){
                return true;
            }
        }
       
        return false;
    }
   
   
    private static void display(int[] arr){
        for(int temp:arr){
            System.out.print(temp+",");
        }
       
        System.out.println();
    }
   
    public static void main(String[] args){
        int[] arr1={1,2,3,4,5,};
        int[] arr2={4,5,6,7,8};

        System.out.print("数组arr1为");
        display(arr1);
        System.out.print("数组arr2为");
        display(arr2);
        System.out.print("arr1和arr2的并集为");
        display(IntegerArrayUtil.union(arr1, arr2));
        System.out.print("arr1和arr2的交集为");
        display(IntegerArrayUtil.intersact(arr1, arr2));
        System.out.print("arr1和arr2的差集为");
        display(IntegerArrayUtil.minus(arr1, arr2));
    }
}