集合框架相关方法

Map 排序

正序

private <K extends Comparable, V extends Comparable> Map<K, V> sortMapByValues2(Map<K, V> aMap) {
    HashMap<K, V> finalOut = new LinkedHashMap<>();
    aMap.entrySet()
            .stream()
            .sorted((p1, p2) -> p1.getValue().compareTo(p2.getValue()))
            .collect(Collectors.toList()).forEach(ele -> finalOut.put(ele.getKey(), ele.getValue()));
    return finalOut;
}

倒序

private <K extends Comparable, V extends Comparable> Map<K, V> sortMapByValues(Map<K, V> aMap) {
    HashMap<K, V> finalOut = new LinkedHashMap<>();
    aMap.entrySet()
            .stream()
            .sorted((p1, p2) -> p2.getValue().compareTo(p1.getValue()))
            .collect(Collectors.toList()).forEach(ele -> finalOut.put(ele.getKey(), ele.getValue()));
    return finalOut;
}

中文字典排序

public static void main(String[] args){
    String[] arrays = new String[]{" 北京 ", " 安徽 ", " 海南 ", " 大连 "};
    List list = Arrays.asList(arrays);
    System.out.println(list.toString());
    Collections.sort(list, new TestUtil());
    System.out.println(list.toString());
}

public class TestUtil implements Comparator {
    public int compare(Object o1, Object o2) {
        try {
            // 取得比较对象的汉字编码，并将其转换成字符串
            String s1 = new String(o1.toString().getBytes("GB2312"), "ISO-8859-1");
            String s2 = new String(o2.toString().getBytes("GB2312"), "ISO-8859-1");
            // 运用 String 类的 compareTo（）方法对两对象进行比较
            return s1.compareTo(s2);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return 0;
    }
}

隐藏手机号码

int arr[] = new int[]{8,2,1,0,3};
int index[] = new int[]{2,0,3,2,4,0,1,3,2,3,3};
String tel = "";
for (int i: index) {
    System.out.println("index:"+index[i]+",i:"+i+",arr[i]:"+arr[i]);
    tel += arr[i];
}
System.out.println(" 联系："+tel);

根据传递的长度，随机分配 60S 内不重复的数组

public int[] randomNextMinute(int length) {
    int[] arr = new int[length];
    for (int i = 0; i < arr.length; i++) {
        int ran;
        while (true) {
            ran = (int) (Math.random() * 60);
            if (ran > 60) {
                ran = ran - 60;
            }
            boolean tag = false;
            for (int j = 0; j < arr.length; j++) {
                if (arr[j] == ran) {
                    tag = true;
                }
            }
            if (!tag) {
                break;
            }
        }
        arr[i] = ran;
    }
    return arr;
}

javascript 循环生成 10 个不重复的随机数

$(function() {
    var arr = new Array(10);
    function getrand() {
        for (var i = 0; i < arr.length; i++) {
            var ran = 0;
            while (true) {
                ran = Math.floor(Math.random() * 10);
                //alert(ran);
                var tag = false;
                for (var j = 0; j < arr.length; j++) {
                    if (arr[j] == ran) {
                        tag = true;
                    }
                }
                if (tag == false) {
                    break;
                }
            }
            arr[i] = ran;
            //alert("ran:" + ran);
            //alert("arr:" + arr);
        }
        return arr;
    }
    var count = 0;
    var ranarr = getrand();
    $("input[name=btn]").bind("click",function(){
        for(var i =count;i<ranarr.length;i++){
            if(ranarr[count] == 0){
                ranarr[count] = 10;
            }
            $("p").text(ranarr[count]);
        }
        count++;
    });
});