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Java 复制指定的数组，截断或填充零（如有必要），使副本具有指定的长度。

欢马劈雪

工程师 (已认证)

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复制指定的数组，截断或填充零（如有必要），使副本具有指定的长度。

实例源码：

源代码：

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/*
来 自*
 时 代 J a v a 公 众 号 - N o w J a v  a . c o m
*/

/* --------------------------------------------------------------------

Licensed to the Apache Software Foundation (ASF) under one or more

contributor license agreements.  See the NOTICE file distributed with

this work for additional information regarding copyright ownership.

The ASF licenses this file to You under the Apache License, Version 2.0

(the "License"); you may not use this file except in compliance with

the License.  You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software

distributed under the License is distributed on an "AS IS" BASIS,

WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

See the License for the specific language governing permissions and

limitations under the License.

-------------------------------------------------------------------- */

//package com.nowjava;

public class Main {

public static void main(String[] argv) throws Exception {

byte[] source = new byte[] { 34, 35, 36, 37, 37, 37, 67, 68, 69 };

int newLength = 2;

System.out.println(java.util.Arrays.toString(copyOf(source,

newLength)));

}

/**

* Copies the specified array, truncating or padding with zeros (if

* necessary) so the copy has the specified length. This method is temporary

* replace for Arrays.copyOf() until we start to require JDK 1.6.

* @param source

*            the array to be copied

* @param newLength

*            the length of the copy to be returned

* @return a copy of the original array, truncated or padded with zeros to

*         obtain the specified length

* @throws NegativeArraySizeException

*             if <tt>newLength</tt> is negative

* @throws NullPointerException

*             if <tt>original</tt> is null

public static byte[] copyOf(byte[] source, int newLength) {

byte[] result = new byte[newLength];

System.arraycopy(source, 0, result, 0,

Math.min(source.length, newLength));//时 代 J a v a 提 供

return result;

}

/**

* This is really a debugging version of <code>System.arraycopy()</code>.

* Use it to provide better exception messages when copying arrays around.

* For production use it's better to use the original for speed.

public static void arraycopy(byte[] src, int src_position, byte[] dst,

int dst_position, int length) {

if (src_position < 0)

throw new IllegalArgumentException(

"src_position was less than 0.  Actual value "

+ src_position);

if (src_position >= src.length)

throw new IllegalArgumentException(

"src_position was greater than src array size.  Tried to write starting at position "

+ src_position

+ " but the array length is "

+ src.length);

if (src_position + length > src.length)

throw new IllegalArgumentException(

"src_position + length would overrun the src array.  Expected end at "

+ (src_position + length) + " actual end at "

+ src.length);

if (dst_position < 0)

throw new IllegalArgumentException(

"dst_position was less than 0.  Actual value "

+ dst_position);

if (dst_position >= dst.length)
/**代码未完, 请加载全部代码(NowJava.com).**/

编辑/阅读全部代码

执行结果：

本文系作者在时代Java发表，未经许可，不得转载。如有侵权，请联系nowjava@qq.com删除。

编辑于 2020-03-26 09:23:272020-03-26 09:23:27

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