binarySearch原理：

public static index halfSearch(List<String> list, String key)

{

int max,min,mid;

max = list.size()-1;

min = 0;

while(min<=max)

{

        mid = (max+min) >>1;

        String str = list.get(mid);

        int num = str.compareTo(key);

        if(num > 0)

                max = mid – 1;

        else if(num < 0)

                min = min + 1;

        return min;//如果是Collections.binarySearch()，它是在min后面的位置-(接入点) - 1

}

}

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Collections.fill(list, “pp”);

将集合中的元素全部替换成为pp

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Collections.replaceAll(list, “oldValue”, “newValue”);

相同于：

list.set(index, “newValue”);

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Collections.reverse(list);

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Collections.swap(list, 1, 2);//角标1、角标2对换

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Collections.shuffle(list);//随机排列list

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