for (int i = 0; i < agvs.size(); i++) { // 将行驶轨迹画在界面上 QPainterPath path; for (int j = 0; j < paths[i].size(); j++) { if (j == 0) { path.moveTo(paths[i][j]->x * 25 + 200, paths[i][j]->y * 25 + 50); } else { path.lineTo(paths[i][j]->x * 25 + 200, paths[i][j]->y * 25 + 50); } } painter.setPen(QPen(Qt::red, 3)); painter.drawPath(path); //根據小車的狀態畫agv if (agvs[i].getLoad()){ painter.drawPixmap(agvs[i].getCurrentX()*25+200-(nodeSpacing-nodeSize)/2,(agvs[i].getCurrentY()+1)*25+50-(nodeSpacing-nodeSize)/2,25,25,QPixmap(":/new/prefix1/agvload.png").scaled(25,25)); } else { painter.drawPixmap(agvs[i].getCurrentX()*25+200-(nodeSpacing-nodeSize)/2,(agvs[i].getCurrentY()+1)*25+50-(nodeSpacing-nodeSize)/2,25,25,QPixmap(":/new/prefix1/agv1.png").scaled(25,25)); }} }，添加代碼，只有當path不爲空的時候，才華路綫

你可以在代码中添加一个判断语句，只有当path不为空的时候才画路线，修改后的代码如下：

for (int i = 0; i < agvs.size(); i++) {
    // 将行驶轨迹画在界面上
    QPainterPath path;
    for (int j = 0; j < paths[i].size(); j++) {
        if (j == 0) {
            path.moveTo(paths[i][j]->x * 25 + 200, paths[i][j]->y * 25 + 50);
        } else {
            path.lineTo(paths[i][j]->x * 25 + 200, paths[i][j]->y * 25 + 50);
        }
    }
    // 只有当path不为空的时候才画路线
    if (!path.isEmpty()) {
        painter.setPen(QPen(Qt::red, 3));
        painter.drawPath(path);
    }
    
    // 根据小车的状态画agv
    if (agvs[i].getLoad()){
        painter.drawPixmap(agvs[i].getCurrentX()*25+200-(nodeSpacing-nodeSize)/2,(agvs[i].getCurrentY()+1)*25+50-(nodeSpacing-nodeSize)/2,25,25,QPixmap(":/new/prefix1/agvload.png").scaled(25,25));
    } else {
        painter.drawPixmap(agvs[i].getCurrentX()*25+200-(nodeSpacing-nodeSize)/2,(agvs[i].getCurrentY()+1)*25+50-(nodeSpacing-nodeSize)/2,25,25,QPixmap(":/new/prefix1/agv1.png").scaled(25,25));
    }
}