目录
public static List asList(T... a)：将多个参数转换为ArrayList
public static int binarySearch(byte[] a, byte key)：查询元素第一次出现的位置
char[]、double[]、float[]、int[]、long[]、Object[]、short[]、T[]均有此方法
public static int binarySearch(byte[] a, int fromIndex, int toIndex,byte key)：指定范围key第一次出现的位置
char[]、double[]、float[]、int[]、long[]、Object[]、short[]、T[]均有此方法
public static char[] copyOf(char[] original, int newLength)：复制数组
boolean[]、char[]、double[]、float[]、int[]、long[]、Object[]、short[]、T[]均有此方法
public static boolean[] copyOfRange(boolean[] original, int from, int to) ：复制数组某一段
boolean[]、char[]、double[]、float[]、int[]、long[]、Object[]、short[]、T[]均有此方法
public static boolean equals(byte[] a, byte[] a2)：长度相等，元素相等
boolean[]、char[]、double[]、float[]、int[]、long[]、Object[]、short[]均有此方法
public static void fill(boolean[] a, boolean val)：用val替换数组中所有的值
boolean[]、char[]、double[]、float[]、int[]、long[]、Object[]、short[]均有此方法
public static void fill(int[] a, int fromIndex, int toIndex, int val)：用val替换数组指定范围的值
boolean[]、char[]、double[]、float[]、int[]、long[]、Object[]、short[]均有此方法
public static int hashCode(int a[])：计算hashCode方法
boolean[]、char[]、double[]、float[]、int[]、long[]、Object[]、short[]均有此方法
public static void parallelSort(byte[] a)：对数组进行并发排序
boolean[]、char[]、double[]、float[]、int[]、long[]、Object[]、short[]均有此方法
public static void parallelPrefix(int[] array, IntBinaryOperator op)：修改的值是1---length-1，位置0的元素不会被修改
double[]、int[]、long[]、T[]均有此方法
double[]、int[]、long[]、T[]均有此方法
public static void parallelSetAll(int[] array, IntUnaryOperator generator)：并发修改
double[]、int[]、long[]、T[]均有此方法
public static void setAll(int[] array, IntUnaryOperator generator)：单线程修改修改
double[]、int[]、long[]、T[]均有此方法
public static void sort(int[] a)：升序排序
char[]、double[]、float[]、int[]、long[]、Object[]、short[]均有此方法
public static IntStream stream(int[] array)
public static String toString(boolean[] a)：格式化输出
char[]、double[]、float[]、int[]、long[]、Object[]、short[]均有此方法
常用方法总结
public static <T> List<T> asList(T... a)：将多个参数转换为ArrayList
public class Test {
public static void main(String[] args) {
List<Integer> list = Arrays.asList(1, 2, 3, 4, 5);
System.out.println(list);
List<String> list1 = Arrays.asList("1","2","3");
System.out.println(list1);
List<Long> list2 = Arrays.asList(1L,2L);
System.out.println(list2);
}
}
结果：
[1, 2, 3, 4, 5]
[1, 2, 3]
[1, 2]
public static int binarySearch(byte[] a, byte key)：查询元素第一次出现的位置
char[]、double[]、float[]、int[]、long[]、Object[]、short[]、T[]均有此方法
public class Test {
public static void main(String[] args) {
byte[] a = {'a','b','c','a'};
//底层采用二分法，所以要先对数组进行排序
Arrays.sort(a);
System.out.println(Arrays.binarySearch(a, (byte) 'a'));
}
}
结果：
0
public static int binarySearch(byte[] a, int fromIndex, int toIndex,byte key)：指定范围key第一次出现的位置
char[]、double[]、float[]、int[]、long[]、Object[]、short[]、T[]均有此方法
public class Test {
public static void main(String[] args) {
byte[] a = {(byte)'a',(byte)'b',(byte)'c',(byte)'a'};
//底层采用二分法，所以要先对数组进行排序
Arrays.sort(a);
System.out.println(Arrays.binarySearch(a,1,a.length, (byte) 'a'));
}
}
结果：
1
public static char[] copyOf(char[] original, int newLength)：复制数组
boolean[]、char[]、double[]、float[]、int[]、long[]、Object[]、short[]、T[]均有此方法
public class Test {
public static void main(String[] args) {
byte[] a = {(byte)'a',(byte)'b',(byte)'c',(byte)'a'};
//底层采用二分法，所以要先对数组进行排序
byte[] bytes = Arrays.copyOf(a, a.length);
for (int i = 0; i < bytes.length; i++) {
System.out.println(bytes[i]);
}
}
}
结果：
97
98
99
97
public static boolean[] copyOfRange(boolean[] original, int from, int to) ：复制数组某一段
boolean[]、char[]、double[]、float[]、int[]、long[]、Object[]、short[]、T[]均有此方法
public class Test {
public static void main(String[] args) {
byte[] a = {(byte)'a',(byte)'b',(byte)'c',(byte)'a'};
//底层采用二分法，所以要先对数组进行排序
byte[] bytes = Arrays.copyOfRange(a,2, a.length);
for (int i = 0; i < bytes.length; i++) {
System.out.println(bytes[i]);
}
}
}
结果：
99
97
public static boolean equals(byte[] a, byte[] a2)：长度相等，元素相等
boolean[]、char[]、double[]、float[]、int[]、long[]、Object[]、short[]均有此方法
public class Test {
public static void main(String[] args) {
byte[] a = {(byte)'a',(byte)'b',(byte)'c',(byte)'a'};
byte[] bytes = Arrays.copyOf(a, a.length);
//长度相等，每个元素相等，返回true
System.out.println(Arrays.equals(a,bytes));
}
}
结果：
true
public static void fill(boolean[] a, boolean val)：用val替换数组中所有的值
boolean[]、char[]、double[]、float[]、int[]、long[]、Object[]、short[]均有此方法
public class Test {
public static void main(String[] args) {
int[] a = {1, 2, 3, 4};
Arrays.fill(a, 5);
for (int i = 0; i < a.length; i++) {
System.out.println(a[i]);
}
}
}
结果：
5
5
5
5
public static void fill(int[] a, int fromIndex, int toIndex, int val)：用val替换数组指定范围的值
boolean[]、char[]、double[]、float[]、int[]、long[]、Object[]、short[]均有此方法
public class Test {
public static void main(String[] args) {
int[] a = {1, 2, 3, 4};
Arrays.fill(a, 0,2,5);
for (int i = 0; i < a.length; i++) {
System.out.println(a[i]);
}
}
}
结果
5
5
3
4
public static int hashCode(int a[])：计算hashCode方法
boolean[]、char[]、double[]、float[]、int[]、long[]、Object[]、short[]均有此方法
public class Test {
public static void main(String[] args) {
int[] a = {1, 2, 3, 4};
System.out.println(Arrays.hashCode(a));
}
}
结果：
955331
public static void parallelSort(byte[] a)：对数组进行并发排序
boolean[]、char[]、double[]、float[]、int[]、long[]、Object[]、short[]均有此方法
public class Test {
public static void main(String[] args) {
int[] a = {1,8,51,13,46,11,22};
Arrays.parallelSort(a);
System.out.println(Arrays.toString(a));
}
}
结果：
[1, 8, 11, 13, 22, 46, 51]
public static void parallelPrefix(int[] array, IntBinaryOperator op)：修改的值是1---length-1，位置0的元素不会被修改
double[]、int[]、long[]、T[]均有此方法
public class Test {
public static void main(String[] args) {
int[] a = {2,8,51,13,46,11,22};
System.out.println(Arrays.toString(a));
Arrays.parallelPrefix(a, new IntBinaryOperator() {
@Override
public int applyAsInt(int left, int right) {
//left当前元素前一个索引的值（2,8,51,13,46,11）即：0---length-2
//right:当前索引的元素（8,51,13,46,11,22）即：1---length-1
System.out.println(left+":"+right);
//修改的值是1---length-1，位置0的元素不会被修改
return 2*right;
}
});
System.out.println(Arrays.toString(a));
}
}
结果：除了元素1，其他元素都被扩大了两倍
[2, 8, 51, 13, 46, 11, 22]
2:8
16:51
102:13
26:46
92:11
22:22
[2, 16, 102, 26, 92, 22, 44]
public static void parallelPrefix(int[] array, int fromIndex,int toIndex, IntBinaryOperator op)：修改指定范围内的值
double[]、int[]、long[]、T[]均有此方法
public class Test {
public static void main(String[] args) {
int[] a = {2,8,51,13,46,11,22};
System.out.println(Arrays.toString(a));
Arrays.parallelPrefix(a,1,4, new IntBinaryOperator() {
@Override
public int applyAsInt(int left, int right) {
//left当前元素前一个索引的值（2,8,51,13,46,11）即：0---length-2
//right:当前索引的元素（8,51,13,46,11,22）即：1---length-1
System.out.println(left+":"+right);
//修改的值是1---length-1，位置0的元素不会被修改
return 2*right;
}
});
System.out.println(Arrays.toString(a));
}
}
结果：（1,4）内元素被修改
[2, 8, 51, 13, 46, 11, 22]
8:51
102:13
[2, 8, 102, 26, 46, 11, 22]
public static void parallelSetAll(int[] array, IntUnaryOperator generator)：并发修改
double[]、int[]、long[]、T[]均有此方法
public class Test {
public static void main(String[] args) {
int[] a = {2,8,51,13,46,11,22};
System.out.println(Arrays.toString(a));
Arrays.parallelSetAll(a, new IntUnaryOperator() {
@Override
public int applyAsInt(int operand) {
//operand当前数组的索引
System.out.println(operand);
return operand*2;
}
});
System.out.println(Arrays.toString(a));
}
}
结果：因为是并发执行，所以索引输出的顺序是不固定的
[2, 8, 51, 13, 46, 11, 22]
4
3
5
0
6
1
2
[0, 2, 4, 6, 8, 10, 12]
public static void setAll(int[] array, IntUnaryOperator generator)：单线程修改修改
double[]、int[]、long[]、T[]均有此方法
public class Test {
public static void main(String[] args) {
int[] a = {2,8,51,13,46,11,22};
System.out.println(Arrays.toString(a));
Arrays.setAll(a, new IntUnaryOperator() {
@Override
public int applyAsInt(int operand) {
//operand当前数组的索引
System.out.println(operand);
return operand*2;
}
});
System.out.println(Arrays.toString(a));
}
}
结果：由于是单线程，所以operand是顺序输出的
[2, 8, 51, 13, 46, 11, 22]
0
1
2
3
4
5
6
[0, 2, 4, 6, 8, 10, 12]
public static void sort(int[] a)：升序排序
char[]、double[]、float[]、int[]、long[]、Object[]、short[]均有此方法
public class Test {
public static void main(String[] args) {
int[] a = {2,8,51,13,46,11,22};
Arrays.sort(a);
System.out.println(Arrays.toString(a));
}
}
结果：
[2, 8, 11, 13, 22, 46, 51]
public static IntStream stream(int[] array)
public class Test {
public static void main(String[] args) {
int[] a = {2,8,51,13,46,11,22};
IntStream stream = Arrays.stream(a);
System.out.println( Arrays.toString(stream.toArray()));
System.out.println(Arrays.toString(a));
}
}
结果：
[2, 8, 51, 13, 46, 11, 22]
[2, 8, 51, 13, 46, 11, 22]
public static String toString(boolean[] a)：格式化输出
char[]、double[]、float[]、int[]、long[]、Object[]、short[]均有此方法
public class Test {
public static void main(String[] args) {
int[] a = {2,8,51,13,46,11,22};
System.out.println(Arrays.toString(a));
}
}
结果：
[2, 8, 51, 13, 46, 11, 22]