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  • java数组使用技巧

    参考网上文章,总结了一下java数组使用技巧,如下:

    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
    		}*/
    
    		
    	}
    }
    


     

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  • 原文地址:https://www.cnblogs.com/suncoolcat/p/3362279.html
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