注意一:二维数组的定义方式
// 1:
int[][] array = {{1,2,3},{4,5,6,7}};
// 2:
int[][] array1 = new int[][]{{1,2,3},{4,5,6,7}};
// 3:
int[][] array2 = new int[2][3];
注意二: 二维数组的打印方式
int[][] array = new int[2][3];
for (int i = 0; i < 2; i++) {
for (int j = 0; j < 3; j++) {
System.out.print(array[i][j] + " ");
}
System.out.println();
//一行打印完再打印下一行
}
//方式二:
System.out.println(Arrays.deepToString(array));
//方式三:
for (int[] index : array) {
System.out.println(Arrays.toString(index));
}
/*
0 0 0
0 0 0
[[0, 0, 0], [0, 0, 0]]
[0, 0, 0]
[0, 0, 0]
*/
注意三:二维数组的内存布局
二维数组其实是一个简单的一维数组
int[][] array = {{1,2,3,4},{5,6,7,8,9,10}};
System.out.println(array);
System.out.println(Arrays.toString(array));
System.out.println(array[0]);
System.out.println(array[1]);
System.out.println(Arrays.toString(array[0]));
System.out.println(Arrays.toString(array[1]));
System.out.println(Arrays.deepToString(array));
}
/*
[[I@1b6d3586
[[I@4554617c, [I@74a14482]
[I@4554617c
[I@74a14482
[1, 2, 3, 4]
[5, 6, 7, 8, 9, 10]
[[1, 2, 3, 4], [5, 6, 7, 8, 9, 10]]
*/
Arrays.toString(array) 的理解:通过引用array 找的其指向的一维数组,并从头到尾打印出内容。
注意四:不规则二维数组的定义方式
int[][] array = new int[2][]; //必须要有行
array[0] =new int[]{1,2,3,4,5,6};
array[1] =new int[]{9,8,7};
System.out.println(Arrays.deepToString(array));
// [[1, 2, 3, 4, 5, 6], [9, 8, 7]]
注意五:冒泡排序
public static void main1(String[] args) {
Scanner scanner = new Scanner(System .in);
int n = scanner.nextInt();
int[] array = new int[n];
for(int i = 0 ; i < n ; i++){
array[i] = scanner.nextInt();
}
for (int i = 0; i < array.length - 1; i++) { //比较的趟数
for (int j = 0; j < n-i-1 ; j++) { //比较的次数
if(array[j] > array[j+1]){
int temp = array[j];
array[j] = array[j+1];
array[j+1] = temp;
}
}
}
System.out.println(Arrays.toString(array));
}
}
优化:
public static void main2(String[] args) {
Scanner scanner = new Scanner(System .in);
int n = scanner.nextInt();
int[] array = new int[n];
for(int i = 0 ; i < n ; i++){
array[i] = scanner.nextInt();
}
for (int i = 0; i < array.length - 1; i++) { //比较的趟数
int flg = -1;
for (int j = 0; j < n-i-1 ; j++) { //比较的次数
if(array[j] > array[j+1]){
int temp = array[j];
array[j] = array[j+1];
array[j+1] = temp;
flg = 1;
}
}
if(flg == -1){
break;
}
}
System.out.println(Arrays.toString(array));
}
本文含有隐藏内容,请 开通VIP 后查看