在Java 9中，Arrays類別新增了哪些新方法？

Arrays類別可以包含各種操作陣列的方法，並且還包含靜態工廠方法，允許將陣列視為清單。 Java 9為Arrays類別加入了三個重要的方法：Arrays.equals()，Arrays.compare()和Arrays.mismatch()。

Arrays.equal() - 在Java 9中，Arrays.equals()方法加入了幾個重載方法。新方法為提供的兩個陣列新增了fromIndex和toIndex參數。這些方法根據它們的相對索引位置檢查兩個陣列的相等性。

Syntax

<strong>public static boolean equals(int[] a, int aFromIndex, int aToIndex, int[] b, int bFromIndex, int bToIndex)</strong>

在上述語法中，如果兩個指定的int數組和指定的範圍內的元素相等，則該方法傳回true。第二個方法對於char數組也是一樣的。

範例

import java.util.Arrays;
public class CompareArrayTest {
   public static void arrayEqualsTest() {
      int[] existRows = {0, 1, 2, 3, 4, 5};
      int[] newRows = {3, 4, 5, 1, 2, 0};
      System.out.println(<strong>Arrays</strong>.<strong>equals</strong>(existRows, newRows));
      System.out.println(<strong>Arrays</strong>.<strong>equals</strong>(existRows, 1, 3, newRows, 3, 5));
      System.out.println(<strong>Arrays</strong>.<strong>equals</strong>(existRows, 3, 5, newRows, 0, 2));
   }
   public static void main(String args[]) {
      CompareArrayTest.arrayEqualsTest();
   }
}

Output

false
true
true

#Arrays.compare() − In Java 9, few parameters have added to the Arrays.compare() method. With fromIndex/toIndex parameters that are used for relative position comparison.

Syntaxx

#In the above syntax, the method compares two int arrays

lexicographically over the specified ranges.

Example

<strong>public static int compare(int[] a, int aFromIndex, int aToIndex, int[] b, int bFromIndex, int bToIndex)</strong>

Output

import java.util.Arrays;
public class LexicographicalArraysTest {
   public static void main(String args[]) {
      LexicographicalArraysTest.compareSliceArraysTest();
   }
   public static void compareSliceArraysTest() {
      int[] tomMarks = {5, 6, 7, 8, 9, 10};
      int[] daisyMarks = {5, 6, 7, 10, 9, 10};
      int[] maryMarks = {5, 6, 7, 8};
      System.out.println(<strong>Arrays.compare</strong>(tomMarks, 0, 3, daisyMarks, 0, 3));
      System.out.println(<strong>Arrays.compare</strong>(tomMarks, 0, 4, maryMarks, 0, maryMarks.length));
      System.out.println(<strong>Arrays.compare</strong>(daisyMarks, 0, 4, maryMarks, 0, maryMarks.length));
   }
}

Example

<strong>0
0
1</strong>

Output

<strong>public static int mismatch(int[] a, int aFromIndex, int aToIndex, int[] b, int bFromIndex, int bToIndex)</strong>

Arrays.mismatch() −

In Java 9, there are other overloaded methods of the

Arrays.mismatch()

method that enables us to find and return the index of the first mismatch between two slices of arrays.Syntax

import java.util.Arrays;
public class MismatchMethodTest {
   public static void main(String[] args) {
      MismatchMethodTest.mismatchArraysTest();
   }
   public static void mismatchArraysTest() {
      int[] a = {1, 2, 3, 4, 5};
      int[] b = {1, 2, 3, 4, 5};
      int[] c = {1, 2, 4, 4, 5, 6};
      System.out.println(<strong>Arrays.mismatch</strong>(a, b));
      System.out.println(<strong>Arrays.mismatch</strong>(a, c));
      System.out.println(<strong>Arrays.mismatch</strong>(a, 0, 2, c, 0, 2));
      System.out.println(<strong>Arrays.mismatc</strong><strong>h</strong>(a, 0, 3, c, 0, 3));
      System.out.println(<strong>Arrays.mismatch</strong>(a, 2, a.length, c, 2, 5));
   }
}

In the above syntax, the method finds and returns the

relative 

##index 

#index 

#index 

of the first mismatch between two int arrays over the specified range. It returns -1 if no mismatch has found. The index in the range of 0 (inclusive) up to the length (inclusive) of the smaller range.###ler range.### ###Example###

<strong>-1
2
-1
2
0</strong>

###Output###rrreee###

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