Java 1.5（或者说Java 5.0、Tiger）给我们带来了很多新特性，这些新特性都有哪些呢？让我们拭目以待。今天，我们先来看看Arrays类，一个全部由静态方法构成的类，提供了许多有用的操作数组的方法。
我们先来看一个示例：
package
com.jiang.tiger.chap1;
import
java.util.Arrays;
 
public
class
ArraysTester
{
private
int
[] ar;
 
public
ArraysTester(
int
numValues)
{
ar
=
new
int
[numValues];
for
(
int
i
=
0
; i
<
ar.length; i
++
)
{
ar[i]
=
(
1000
-
(
300
+
i));
 }
}
public
int
[] get( )
{
return
ar;
}
public
static
void
main(String[] args)
{
ArraysTester tester
=
new
ArraysTester(
50
);
int
[] myArray
=
tester.get( );
//
比较两个数组
int
[] myOtherArray
=
tester.get().clone( );
if
(Arrays.equals(myArray, myOtherArray))
{
System.out.println(
"
The two arrays are equal!
"
);
}
else
{
System.out.println(
"
The two arrays are not equal!
"
);
}
//
用指定的值填充数组
Arrays.fill(myOtherArray,
2
,
10
,
new
Double(Math.PI).intValue( ));
myArray[
30
]
=
98
;
//
打印无序数组
System.out.println(
"
Here's the unsorted array
"
);
System.out.print(Arrays.toString(myArray));
System.out.println( );
//
数组排序
Arrays.sort(myArray);
//
打印有序数组
System.out.println(
"
Here's the sorted array
"
);
System.out.print(Arrays.toString(myArray));
System.out.println( );
//
用二分搜索法查找指定的值。
int
index
=
Arrays.binarySearch(myArray,
98
);
System.out.println(
"
98 is located in the array at index
"
+
index);
//
数组“深层次内容”的字符串表示形式，简而言之，将多维数组所有元素转换为字符串。
String[][] ticTacToe
=
{
{
"
X
"
,
"
O
"
,
"
O
"
}
,
{
"
O
"
,
"
X
"
,
"
X
"
}
,
{
"
X
"
,
"
O
"
,
"
X
"
}
}
;
System.out.println(Arrays.deepToString(ticTacToe));
String[][] ticTacToe2
=
{
{
"
O
"
,
"
O
"
,
"
X
"
}
,
{
"
O
"
,
"
X
"
,
"
X
"
}
,
{
"
X
"
,
"
O
"
,
"
X
"
}
}
;
String[][] ticTacToe3
=
{
{
"
X
"
,
"
O
"
,
"
O
"
}
,
{
"
O
"
,
"
X
"
,
"
X
"
}
,
{
"
X
"
,
"
O
"
,
"
X
"
}
}
;
//
比较两个数组是否“深层次相等”，适用于任何维次的数组
if
(Arrays.deepEquals(ticTacToe, ticTacToe2))
{
System.out.println(
"
Boards 1 and 2 are equal.
"
);
}
else
{
System.out.println(
"
Boards 1 and 2 are not equal.
"
);
}
if
(Arrays.deepEquals(ticTacToe, ticTacToe3))
{
System.out.println(
"
Boards 1 and 3 are equal.
"
);
}
else
{
System.out.println(
"
Boards 1 and 3 are not equal.
"
);
}
System.out.println(
"
Here's the array of the ArrayTester
"
);
System.out.print(Arrays.toString(tester.get()));
System.out.println( );
System.out.println(
"
Here's myArray
"
);
System.out.print(Arrays.toString(myArray));
System.out.println( );
System.out.println(
"
Here's myOtherArray
"
);
System.out.print(Arrays.toString(myOtherArray));
System.out.println( );
Object[] a
=
new
Object[
2
];
a[
0
]
=
1
;
a[
1
]
=
a;
System.out.println(Arrays.deepHashCode(a));
}
 }
下面再看看输出：
The two arrays are equal!
Here's the unsorted array
[
700, 699, 698, 697, 696, 695, 694, 693, 692, 691, 690, 689, 688, 687, 686, 685, 684, 683, 682, 681, 680, 679, 678, 677, 676, 675, 674, 673, 672, 671, 98, 669, 668, 667, 666, 665, 664, 663, 662, 661, 660, 659, 658, 657, 656, 655, 654, 653, 652, 651
]
Here's the sorted array
[
98, 651, 652, 653, 654, 655, 656, 657, 658, 659, 660, 661, 662, 663, 664, 665, 666, 667, 668, 669, 671, 672, 673, 674, 675, 676, 677, 678, 679, 680, 681, 682, 683, 684, 685, 686, 687, 688, 689, 690, 691, 692, 693, 694, 695, 696, 697, 698, 699, 700
]
98
is located in the array at index
0
[
[X, O, O
]
,
[
O, X, X
]
,
[
X, O, X
]
]
Boards
1
and
2
are not equal.
Boards
1
and
3
are equal.
Here's the array of the ArrayTester
[
98, 651, 652, 653, 654, 655, 656, 657, 658, 659, 660, 661, 662, 663, 664, 665, 666, 667, 668, 669, 671, 672, 673, 674, 675, 676, 677, 678, 679, 680, 681, 682, 683, 684, 685, 686, 687, 688, 689, 690, 691, 692, 693, 694, 695, 696, 697, 698, 699, 700
]
Here's myArray
[
98, 651, 652, 653, 654, 655, 656, 657, 658, 659, 660, 661, 662, 663, 664, 665, 666, 667, 668, 669, 671, 672, 673, 674, 675, 676, 677, 678, 679, 680, 681, 682, 683, 684, 685, 686, 687, 688, 689, 690, 691, 692, 693, 694, 695, 696, 697, 698, 699, 700
]
Here's myOtherArray
[
700, 699, 3, 3, 3, 3, 3, 3, 3, 3, 690, 689, 688, 687, 686, 685, 684, 683, 682, 681, 680, 679, 678, 677, 676, 675, 674, 673, 672, 671, 670, 669, 668, 667, 666, 665, 664, 663, 662, 661, 660, 659, 658, 657, 656, 655, 654, 653, 652, 651
]
Exception in thread
"
main
"
java.lang.StackOverflowError
at java.util.Arrays.deepHashCode(Unknown Source)...
上面的程序使用了Arrays类的大多数方法，下面我们就来看看Arrays到底为我们带来了哪些有用的方法：
1. asList：将指定的数组转换为List；
2. binarySearch：采用二分搜索方法从数组中查找指定的值
3. deepEquals：比较两个数组是否“深层次相等”，5.0引入
4. deepHashCode：计算数组的“深层次哈希码”，5.0引入
5. deepToString：将数组转换为字符串，5.0引入
6. equals：比较两个数组是否相等
7. fill：用指定值填充数组
8. hashCode：计算数组的哈希值，5.0引入
9. sort：对数组排序
10. toString：将数组转换为字符串，5.0引入。
上面的方法中除了4、5、6外，其余方法都比较简单。4、5、6三个方法主要用来操作多维数组，如果有些数组的元素类型本身也是数组，它们会对该元素也调用相同的方法，直至最终没有数组元素的类型为数组。这三个方法功能十分强大，但有一点需要注意：千万不要将自身作为数组元素，例如上面示例中的a[1]=a，这样会导致无限循环，最终导致栈溢出。
|