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概述
提供了数组操作的相关方法#xff0c;连接数组和集合
asList
返回指定数组的列表列表和数组的引用位置相同 Integer[] arrs new Integer[] {1,2,3,4,5,6,7,8,9};ListInteger list Arrays.asList(arrs);System.out.println(list);arrs[5] 100;Syste…Arrays
概述
提供了数组操作的相关方法连接数组和集合
asList
返回指定数组的列表列表和数组的引用位置相同 Integer[] arrs new Integer[] {1,2,3,4,5,6,7,8,9};ListInteger list Arrays.asList(arrs);System.out.println(list);arrs[5] 100;System.out.println(list);//[1, 2, 3, 4, 5, 6, 7, 8, 9]//[1, 2, 3, 4, 5, 100, 7, 8, 9]}binarySearch
二分法查找元素需要进行排序
Integer[] arrs new Integer[] {1,2,3,4,5,6,7,8,9};int num Arrays.binarySearch(arrs, 5);System.out.println(num);
//4copyOf copyOfRange
创建数组副本一个新的数组 Integer[] arrs new Integer[] {1,2,3,4,5,6,7,8,9};Integer[] arrs1 Arrays.copyOf(arrs, 5);for(Integer i : arrs1) {System.out.print(i );}System.out.println();//1 2 3 4 5 arrs1[3] 100;for(Integer i : arrs) {System.out.print(i );}//1 2 3 4 5 6 7 8 9 System.out.println();for(Integer i : arrs1) {System.out.print(i );}//1 2 3 100 5 Integer[] ret Arrays.copyOf(arrs,20,Integer[].class);System.out.println();for(Integer i : ret) {System.out.print(i );}//1 2 3 4 5 6 7 8 9 null null null null null null null null null null nullInteger[] range Arrays.copyOfRange(arrs, 5, 20);System.out.println();for(Integer i : ret) {System.out.print(i );}//1 2 3 4 5 6 7 8 9 null null null null null null null null null null null equals deepEquals
deepEquals 是深层次的比较比如嵌套数组 Integer[] arrs new Integer[] {1,2,3,4,5,6,7,8,9};Integer[] arrs1 new Integer[] {1,2,3,4,5,6,7,8,9};System.out.println(arrs);System.out.println(arrs1);System.out.println(Arrays.equals(arrs, arrs1));
// [Ljava.lang.Integer;2077d4de
// [Ljava.lang.Integer;7591083d
// trueArrays.fill填充数组 public void test5() {Integer[] arrs new Integer[10];Arrays.fill(arrs, 100);for(Integer i : arrs) {System.out.print(i );}//100 100 100 100 100 100 100 100 100 100 }sort public void test6() {Integer[] arrs new Integer[20];for(int i0;i20;i)arrs[i] (int)(Math.random()*100);for(int i:arrs) {System.out.print(i );}System.out.println();//49 40 0 79 4 98 12 81 71 27 9 45 16 17 7 92 63 22 73 22 Arrays.sort(arrs);for(int i:arrs) System.out.print(i );System.out.println();//0 4 7 9 12 16 17 22 22 27 40 45 49 63 71 73 79 81 92 98 Arrays.sort(arrs,(o1,o2)-o2-o1);for(int i:arrs) System.out.print(i );//98 92 81 79 73 71 63 49 45 40 27 22 22 17 16 12 9 7 4 0 }parallelSort
经过比较 速断快与sort使用频率越高越明显数据量越大越明显从1000~10000000开始进行100次测试 public void test7() {//生产1万个元素int len 100000;Integer[] arrs new Integer[len];for(int i0;ilen;i)arrs[i] (int)(Math.random()*100);long t1 System.currentTimeMillis();Arrays.sort(arrs);long t2 System.currentTimeMillis();System.out.println(sort\t(t2-t1));for(int i0;ilen;i)arrs[i] (int)(Math.random()*100);long t3 System.currentTimeMillis();Arrays.parallelSort(arrs);long t4 System.currentTimeMillis();System.out.println(parallelSort\t(t4-t3));System.out.println(------------------------------);}public void test8() {for(int i0;i100;i) {test7();}}sort 35
parallelSort 64
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sort 40
parallelSort 73
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sort 107
parallelSort 53
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sort 73
parallelSort 63
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sort 74
parallelSort 62
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····spliterator 遍历数组 int len 100;Integer[] arrs new Integer[len];for(int i0;ilen;i)arrs[i] (int)(Math.random()*100);SpliteratorInteger s Arrays.spliterator(arrs);s.forEachRemaining((e)-System.out.print(e ));Stream public void test10() {int len 10;Integer[] arrs new Integer[len];for(int i0;ilen;i)arrs[i] (int)(Math.random()*100);ListInteger list Arrays.stream(arrs).collect(Collectors.toList());System.out.println(list);//[56, 33, 59, 63, 55, 37, 68, 52, 53, 3]}setAll parallelSetAll 为所有的元素赋值
parallelSetAll 并行处理速度会快 public void test11() {int len 10;Integer[] array new Integer[len];Arrays.setAll(array, (e)-10);for(int i:array)System.out.print(i );System.out.println();Arrays.parallelSetAll(array, (e)-e 10);for(int i:array)System.out.print(i );// 10 10 10 10 10 10 10 10 10 10
// 10 11 12 13 14 15 16 17 18 19 }parallelPrefix 每个元素都包含对前面的所有元素应用某个操作的累计结果 public void test12() {int len 10;int[] array new int[len];Arrays.parallelPrefix(array, (e,u)-{System.out.println(e \t u);return e 1;});System.out.println();for(int i:array)System.out.print(i );}toString deepToString(嵌套数组) hashCode deepHashCode public void test13() {int len 10;Integer[] arrs new Integer[len];for(int i0;ilen;i)arrs[i] (int)(Math.random()*100);System.out.println(Arrays.toString(arrs));System.out.println(Arrays.hashCode(arrs));}
