Java常见数据结构

数组

int a = new int[10];
int a = {1,2,3,4,5};
​
a.length
Arrays.toString(a)
Arrays.copyOf(a,a.length)
​
Arrays.binarySearch(a,4)

链表

ArrayList

ArrayList<Integer> list = new ArrayList<>();
​
list.add(a);
list.add(a,index);
​
list.remove(index);
list.remove(a);
​
list.get(index);
list.set(index,a);
​
list.clear();
list.contains(Objec o);

栈 Stack

Stack<Integer> s = new Stack<>();
​
s.push(num);
s.pop();
s.empty();
s.peek(); //获取栈顶元素
s.search(num); //判端元素num是否在栈中，如果在返回1，不在返回-1。

队列 Queue

Queue<Integer> q = new Queue<>();
​
q.offer(num);
q.pull();
q.peek();
queue.isEmpty()

集合

哈希

HashMap

Map<int ,String> map = new HashMap<int ,String>();
​
map.get(key);
map.set(key,value);
​
map.containsKey(key);
map.containsValue(value);
​
map.remove(Object key)
map.isEmpty();
map.size();

遍历

使用entrySet遍历

//迭代器
Iterator iter = map1.entrySet().iterator(); 
while (iter.hasNext()) { 
    Map.Entry entry = (Map.Entry) iter.next(); 
    String key = (String) entry.getKey();
    String val = (String)entry.getValue();
}
//foreach
for(Map.Entry<String, String> map:map1.entrySet()) {
    map.getKey();
    map.getValue();
}

使用keySet遍历

//迭代器
Set<String> keys = map.keySet();
Iterator<String> it = keys.iterator();
while(it.hasNext()){
    String key = it.next();
    String value = map.get(key);
}
//foreach
Set<String> keys = map.keySet();
for (String key : keys) {
    String value = map.get(key);
}