queue.getnowait()

This method is used to get an item from the queue without blocking. If the queue is empty, it will raise the `queue.Empty` exception immediately instead of waiting for an item to become available.

Example:

import queue

q = queue.Queue()

try:
    item = q.get_nowait()
except queue.Empty:
    print("Queue is empty")

In the above example, we create a queue object and then try to get an item from it using `get_nowait()` method. Since the queue is empty, it will raise the `queue.Empty` exception and we print a message saying that the queue is empty.

相关问题

优化以下java代码： LinkedList<SystemDynamics> getModelDataSysLog(){ //队列长度为0查询数据库 LocalDateTime now = LocalDateTime.now(); if(LogQueue.queue.size() == 0){ List<SystemDynamics> logs = service.getSysLog(null); for(SystemDynamics dynamics : logs){ dynamics.setLogTitle(dynamics.getOperatorName().substring(0,1)+"**"+dynamics.getLogTitle()); dynamics.setAfterTime(getTimeDifferent(now,dynamics.getOperatorTime())); } LogQueue.queue = new LinkedList<>(logs); if(logs.size()>0) LogQueue.dateTime = logs.get(0).getOperatorTime(); }else{ //队列长度不为0则从库里查数据添加到队列 List<SystemDynamics> logs = service.getSysLog(LogQueue.dateTime); for(SystemDynamics dynamics : logs){ dynamics.setLogTitle(dynamics.getOperatorName().substring(0,1)+"**"+dynamics.getLogTitle()); dynamics.setAfterTime(getTimeDifferent(now,dynamics.getOperatorTime())); } if(logs.size()>0){ if(logs.size() == LogQueue.queue.size()){ LogQueue.queue = new LinkedList<>(logs); }else{ logs.forEach(l->{ LogQueue.offer(l); }); } LogQueue.dateTime = LogQueue.queue.get(0).getOperatorTime(); } } return LogQueue.queue; }

可以考虑以下几个优化点：

1. 避免重复的代码：将for循环中的logs遍历和set操作提取出来，放到一个单独的方法中，避免重复的代码。

2. 使用局部变量：将重复使用的变量logs和now定义为局部变量，避免多次访问。

3. 代码简化：可以使用三目运算符对条件进行判断，避免过多的if-else语句，使代码更简洁。

优化后的代码如下所示：

LinkedList<SystemDynamics> getModelDataSysLog() {
    LocalDateTime now = LocalDateTime.now();
    if (LogQueue.queue.size() == 0) {
        LogQueue.queue = new LinkedList<>(getLogs(null, now));
        if (!LogQueue.queue.isEmpty()) {
            LogQueue.dateTime = LogQueue.queue.get(0).getOperatorTime();
        }
    } else {
        List<SystemDynamics> logs = getLogs(LogQueue.dateTime, now);
        if (!logs.isEmpty()) {
            LogQueue.queue.addAll(logs.size() == LogQueue.queue.size() ? new LinkedList<>(logs) : logs);
            LogQueue.dateTime = LogQueue.queue.get(0).getOperatorTime();
        }
    }
    return LogQueue.queue;
}

private List<SystemDynamics> getLogs(LocalDateTime dateTime, LocalDateTime now) {
    List<SystemDynamics> logs = service.getSysLog(dateTime);
    logs.forEach(l -> {
        l.setLogTitle(l.getOperatorName().substring(0, 1) + "**" + l.getLogTitle());
        l.setAfterTime(getTimeDifferent(now, l.getOperatorTime()));
    });
    return logs;
}

function queue(){ function constructor() { this.items = []; } queue.prototype.enqueue = function(element) { this.items.push(element); }; queue.prototype.dequeue = function() { return this.items.shift(); }; queue.prototype.indexOf = function(element) { return this.items.indexOf(element); }; queue.prototype.set = function(element, index) { if (index < 0 || index >= this.items.length) return; this.items[index] = element; }; queue.prototype.peek = function() { return this.items[0]; }; queue.prototype.isEmpty = function() { return this.items.length === 0; }; } let queue1 = new queue(); queue1.enqueue('A'); queue1.enqueue('B'); queue1.enqueue('C'); console.log(queue1.items); let foundA = queue.indexOf('A'); console.log(foundA); queue.set('x', 1); console.log(queue.items); queue.dequeue(); console.log(queue.items);请帮我修改该代码

好的，我修改了一下代码，注释中有说明：

function Queue() { // 构造函数名首字母应该大写
  this.items = [];
}

Queue.prototype.enqueue = function(element) {
  this.items.push(element);
};

Queue.prototype.dequeue = function() {
  return this.items.shift();
};

Queue.prototype.indexOf = function(element) {
  return this.items.indexOf(element);
};

Queue.prototype.set = function(element, index) {
  if (index < 0 || index >= this.items.length) return;
  this.items[index] = element;
};

Queue.prototype.peek = function() {
  return this.items[0];
};

Queue.prototype.isEmpty = function() {
  return this.items.length === 0;
};

let queue1 = new Queue(); // 构造函数名应该首字母大写
queue1.enqueue('A');
queue1.enqueue('B');
queue1.enqueue('C');
console.log(queue1.items);

let foundA = queue1.indexOf('A'); // 应该是 queue1 而不是 queue
console.log(foundA);

queue1.set('x', 1); // 应该是 queue1 而不是 queue
console.log(queue1.items);

queue1.dequeue(); // 应该是 queue1 而不是 queue
console.log(queue1.items);

希望对你有帮助。