Java Arrays類API

String[] sh = {"guodegang" , "yuqian", "yueyunpeng", "zhanghelun","yuaaaadddd"};
System.out.println(Arrays.toString(sh));//[guodegang, yuqian, yueyunpeng, zhanghelun, yuaaaadddd]
System.out.println(sh.toString());//[Ljava.lang.String;@1b6d3586

//數組排序，parallelSort是并行排序，會把數組拆成子數組，數組越大，性能上優勢越明顯。
Arrays.sort(sh, 1, 3);//指定範圍排序
System.out.println(Arrays.toString(sh));//[guodegang, yueyunpeng, yuqian, zhanghelun, yuaaaadddd]

Arrays.sort(sh);
System.out.println(Arrays.toString(sh));//[guodegang, yuaaaadddd, yueyunpeng, yuqian, zhanghelun]
Arrays.parallelSort(sh);
System.out.println(Arrays.toString(sh));//[guodegang, yuaaaadddd, yueyunpeng, yuqian, zhanghelun]

//二分查找法 ，查找 元素存在 的下标,不存在 傳回 -插入點-1（前提排序）
System.out.println(Arrays.binarySearch(sh, "yuqian"));//3

//判斷兩個數組值是否相同,隻能比較基本類型數組，對象數組不會值相等
int[] sh2 = {1 , 2, 3, 4, 5};
int[] sh3 = {1 , 2, 3, 4, 5};
int[] sh4 = {1 , 2, 3, 4};
System.out.println(Arrays.equals(sh2, sh3));//true
System.out.println(Arrays.equals(sh3, sh4));//false

//數組填充
Arrays.fill(sh, 1, 2, "222");//前算後不算,指定範圍内填充
System.out.println(Arrays.toString(sh));//[guodegang, 222, yueyunpeng, yuqian, zhanghelun]
Arrays.fill(sh, "11111");
System.out.println(Arrays.toString(sh));//[11111, 11111, 11111, 11111, 11111]

//複制數組
String[] sh5 = {"guodegang" , "yuqian", "yueyunpeng", "zhanghelun","yuaaaadddd"};
String[] arrNew = Arrays.copyOfRange(sh5, 1, 3);//指定範圍複制 算前不算厚
System.out.println(Arrays.toString(arrNew));//[yuqian, yueyunpeng]
String[] arrNew2 = Arrays.copyOf(sh5,4);//要複制的數組，個數
System.out.println(Arrays.toString(arrNew2));//[guodegang, yuqian, yueyunpeng, zhanghelun]