数组

//数组元素对换

int[] arr=new int[]{4,5,6,8};
int temp=arr[2];//获取第3个元素6
//交换数组下标为2和3的两个相邻元素的值
//int temp=arr[2];
arr[2]=arr[3];
arr[3]=temp;
for(int i=0;i<arr.length;i++){
//arr[i]=100;
System.out.println(arr[i]);
}

//数组倒叙输出

int []arr=new int[]{10,20,30,40,50};
for(int i=(arr.length-1);i>=0;i--){
System.out.println(arr[i]);
}

//数组的复制
int[]a ={10,20,30,40,50};
int[]a1=new int[6];
System.arraycopy(a, 1, a1, 0, 4);
for(int i=0;i<a1.length;i++){
System.out.println(a1[i]);
}

//数组扩容

int[] a={10,20,30,40,50};
int[] a1=Arrays.copyOf(a,6);
for(int i=1;i<a1.length;i++){
System.out.println(a1[i]);
}