初始化数组
String[] array1 = {"马超", "马云", "关羽", "刘备", "张飞"}; String[] array2 = new String[]{"黄渤", "张艺兴", "孙红雷", "小猪", "牙哥", "黄磊"};
查看数组的长度
System.out.println("length: " + array1.length);
遍历数组
for (int i = 0; i < array1.length; i++) { System.out.println(array1[i]); }
数组 int ---> string
int[] array3 = {1, 2, 3, 4, 5, 6, 7, 8, 9, 0}; String arrStrings = Arrays.toString(array3); System.out.println(arrStrings);
数组中是否包含某一个值
String a = "codingwhy"; if (Arrays.asList(array1).contains(a)) { System.out.println("codingwhy在这里"); }
将数组转成set集合
Set<String> set = new HashSet<>(Arrays.asList(array2)); System.out.println(set);
将数组转成list集合
List<String> list = new ArrayList<>(); for (int i = 0; i < array2.length; i++) { list.add(array2[i]); } String[] arrStrings2 = {"1", "2", "3"}; List<String> list2 = java.util.Arrays.asList(arrStrings2); System.out.println(list2);
数组排序
int[] arr4 = {3, 7, 2, 1, 9}; Arrays.sort(arr4); for (int i = 0; i < arr4.length; i++) { System.out.println(arr4[i]); }
从第几个到第几个之间的进行排序
int[] arr5 = {3, 7, 2, 1, 9, 3, 45, 7, 8, 8, 3, 2, 65, 34, 5}; Arrays.sort(arr5, 1, 4); for (int i = 0; i < arr5.length; i++) { System.out.println(arr5[i]); }
复制数组
int[] arr6 = {3, 7, 2, 1}; int[] arr7 = Arrays.copyOf(arr6, 10); //指定新数组的长度
只复制从索引[1]到索引[3]之间的元素(不包括索引[3]的元素)
int[] arr8 = Arrays.copyOfRange(arr6, 1, 3); for (int i = 0; i < arr8.length; i++) { System.out.println(arr8[i]); }
比较两个数组
int[] arr9 = {1, 2, 3, 4, 5, 6, 7, 8, 9, 0}; boolean arr10 = Arrays.equals(arr6, arr9); System.out.println(arr10);
利用set的特性去重复
int[] arr11 = {1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 3, 2, 4, 5, 6, 7, 4, 32, 2, 1, 1, 4, 6, 3}; Set<Integer> set2 = new HashSet<>(); for (int i = 0; i < arr11.length; i++) { set2.add(arr11[i]); } System.out.println(set2); int[] arr12 = new int[set2.size()]; int j = 0; for (Integer i : set2) { arr12[j++] = i; } System.out.println(Arrays.toString(arr12));
计算最大值
int[] arr = {10, 2, 3, 4, 5, 6, 7, 8, 9, 0, 3, 2, 4, 5, 6, 7, 4, 32, 2, 1, 1, 4, 6, 3}; int max = arr[0]; for (int i = 1; i < arr.length; i++) { if (arr[i] > max) { max = arr[i]; } } System.out.println("Max is " + max);
计算最小值
int[] arr = {10, 2, 3, 4, 5, 6, 7, 8, 9, 0, 3, 2, 4, 5, 6, 7, 4, 32, 2, 1, 1, 4, 6, 3}; int min = arr[0]; for (int i = 0; i < arr.length; i++) { if (arr[i] < min) { min = arr[i]; } } System.out.println("Min is " + min);