java数组使用技巧

package com.beijing.array;

import java.nio.ByteBuffer;
import java.util.Arrays;
import java.util.HashSet;
import java.util.Set;

import org.apache.commons.lang.ArrayUtils;

/**
*
* @description java数组使用技巧
* @author liuchao
* @createTime 2013年10月10日上午10:27:15
*/
public class ArrayTest {

public static void main(String[] args) {

// 1.声明数组
/*
* String[] a = new String[5]; String[] b = {"a","b","c","d","e"};
* String[] c = new String[]{"a","b","c","d","e"};
*/

// 2.在java中输出一个数组
/*
* int[] intArray = {1,2,3,4,5}; String intArrayString =
* Arrays.toString(intArray);
*
* System.out.println(intArray);//[I@de6ced
* System.out.println(intArrayString);//[1, 2, 3, 4, 5]
*/

// 3.从数组中创建列表
/*
* String[] stringArray = {"a","b","c","d","e"}; ArrayList<String>
* arrayList = new ArrayList<String>(Arrays.asList(stringArray));
* System.out.println(arrayList);//[a, b, c, d, e]
*/

// 4.检查数组中是否包含特定值
/*
* String[] stringArray = {"a","b","c","d","e"}; boolean b =
* Arrays.asList(stringArray).contains("a");
* System.out.println(b);//true
*/
// 5.连接连个数组
/*
* int[] intArray = {1,2,3,4,5}; int[] intArray2 = {6,7,8,9,10};
*
* //use apache commons lang library int[] combinedIntArray =
* ArrayUtils.addAll(intArray, intArray2); for (int i = 0; i <
* combinedIntArray.length; i++) {
* System.out.print(combinedIntArray[i]+","); }
*
* //1,2,3,4,5,6,7,8,9,10,
*/
// 6.将数组元素加入到一个独立的字符串中（即用独立的字符串分割数组元素）
/*
* String str = StringUtils.join(new String[]{"a","b","c"}, ",");
* System.out.println(str);//a,b,c
*/

//7.将数组列表转换成一个数组
/*String[] stringArray = { "a", "b", "c", "d", "e" };
ArrayList<String> arrayList = new ArrayList<String>(Arrays.asList(stringArray));

String[] stringArr = new String[arrayList.size()];
arrayList.toArray(stringArr);

for(String s : stringArr){
System.out.println(s);
}*/

//8.将数组转换成一个集合
/*String[] stringArray = { "a", "b", "c", "d", "e" };
Set<String> set = new HashSet<String>(Arrays.asList(stringArray));
System.out.println(set);//[d, e, b, c, a]
*/

//9.反向数组
/*int[] intArray = {1,2,3,4,5};
ArrayUtils.reverse(intArray);
System.out.println(Arrays.toString(intArray));//[5, 4, 3, 2, 1]
*/

//10.删除数组元素
/*int[] intArray = {1,34,3,2,56,13,13,45,2};
int[] removed = ArrayUtils.removeElement(intArray, 2);//删除第一个匹配的元素
System.out.println(Arrays.toString(removed));*/

//11.把整数转换成字节数组
/*byte[] bytes = ByteBuffer.allocate(4).putInt(8).array();

for (byte t : bytes) {
System.out.format("0x%x ", t);//0x0 0x0 0x0 0x8
}*/

//一个整数与0xFF进行&操作，得到该整数的二进制表示

/*ByteBuffer buffer = ByteBuffer.allocate(1024); //分配一定的空间,1024
int i = 90;
buffer.putInt(i);
byte[] array = buffer.array(); //获取该buffer的数组,这个数组是跟该buffer一一对应的
for(int j =0; j <4;j++){
System.out.println(Integer.toBinaryString(array[j] & 0xFF));//1011010
}*/

}
}