java数组、集合使用及相互转换

package com.gooagoo.javautil;

import java.util.Arrays;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;

public class TestMain
{

    public static void main(String[] args)
    {
        /****************************arrays****************************/
        int[] arr = {1,3,2,6};
        for(int iTemp:arr){
            System.out.println(iTemp);
        }
        System.out.println("-------------------------");

        int tarIndex2 = Arrays.binarySearch(arr, 2);  // 数组无序,二分查找
        System.out.println(tarIndex2);                // wrong result index
        System.out.println("-------------------------");

        Arrays.sort(arr);                            // 数组排序
        
        for(int jTemp:arr){
            System.out.println(jTemp);
        }
        System.out.println("-------------------------");

        int tarIndex = Arrays.binarySearch(arr, 2);  // 数组有序,二分查找
        System.out.println(tarIndex);                // right result index
        
        System.out.println("-------------------------");
        
        
        String[] strArr = {"Ai","Jg","eo","ch"};
        String[] strArr2 = new String[4];
        Arrays.fill(strArr2, "l");                                // fill
        System.out.println(Arrays.toString(strArr2));             // toString
        String[] copyStr1 = Arrays.copyOf(strArr, strArr.length); // copy
        System.out.println(Arrays.toString(copyStr1));
        
        System.out.println(Arrays.equals(strArr, copyStr1));     // equals before sort

        Arrays.sort(copyStr1);                                  // sort, 注意，默认排序是区分大小写的
                
        System.out.println("默认(区分大小写)排序：大写在前,小写在后: " + Arrays.toString(copyStr1));
        
        Arrays.sort(copyStr1,String.CASE_INSENSITIVE_ORDER);

        System.out.println("忽略大小写排序: " +Arrays.toString(copyStr1));         //  sort,忽略大小写
        
        Arrays.sort(copyStr1,String.CASE_INSENSITIVE_ORDER);
        Collections.reverse(Arrays.asList(copyStr1));
        System.out.println("忽略大小写逆序排序: " +Arrays.toString(copyStr1));         //  sort,忽略大小写逆序排序

        System.out.println(Arrays.equals(strArr, copyStr1));     // equals,注意：元素顺序是否相同
        
        String[] copyStr2 = Arrays.copyOfRange(strArr,2,strArr.length); // range copy
        System.out.println(Arrays.toString(copyStr2));
        
        System.out.println("------------------------");

        /******************************collections*********************************/
        List<Integer> iList = Arrays.asList(4,3,9,6);
        Iterator<Integer> iIter = iList.iterator();
        while(iIter.hasNext()){
            System.out.println(iIter.next());
        }
        
        System.out.println("-------------------------");

        int index = Collections.binarySearch(iList, 6); // 集合无序,二分查找
        System.out.println(index);
        System.out.println("-------------------------");
        
        Collections.sort(iList);                       // 集合排序
        
        for(Integer temp:iList){
            System.out.println(temp);
        }
        
        System.out.println("-------------------------");
        int index2 = Collections.binarySearch(iList, 6); // 集合有序,二分查找
        System.out.println(index2);
        
        
        /****************************arrays convert to collections*********************/
        System.out.println("-------------------------");

        List<String> strList = Arrays.asList(copyStr1);
        System.out.println(strList.toString());
        
        /***************************collections convert to arrays***********************/
        System.out.println("-------------------------");
        String[] resArr = (String[])strList.toArray();
        System.out.println(Arrays.toString(resArr));
    }
}