How to Combine Lists in Dart? dart里合并list

Using addAll() method to add all the elements of other lists to the existing list

main() { 
    
  // Creating lists 
  List gfg1 = ['Welcome','to']; 
  List gfg2 = ['GeeksForGeeks']; 
    
  // Combining lists 
  gfg1.addAll(gfg2); 
    
  // Printing combined list 
  print(gfg1); 
}

Creating a new list by adding two or more list using addAll() method of list

// Main function 
main() { 
    
  // Creating lists 
  List gfg1 = ['Welcome','to']; 
  List gfg2 = ['GeeksForGeeks']; 
    
  // Combining lists 
  var newgfgList = new List.from(gfg1)..addAll(gfg2); 
    
  // Printing combined list 
  print(newgfgList); 
}

Creating a new list by adding two or more list using expand() method of list

// Main function 
main() { 
    
  // Creating lists 
  List gfg1 = ['Welcome']; 
  List gfg2 = ['to']; 
  List gfg3 = ['GeeksForGeeks']; 
    
  // Combining lists 
  var newgfgList = [gfg1, gfg2, gfg3].expand((x) => x).toList(); 
    
  // Printing combined list 
  print(newgfgList); 
}

apread运算符： ...

// Main function 
main() { 
    
  // Creating lists 
  List gfg1 = ['Welcome']; 
  List gfg2 = ['to']; 
    
  // Combining lists 
  var newgfgList = [...gfg1, ...gfg2, 'GeeksForGeeks']; 
    
  // Printing combined list 
  print(newgfgList); 
}

写这篇， 是有一个需求没有解决， 网上找的替代方案。 dart三目运算符里怎们包起来代码？

var item = [1, 2, 3];
var one = [...item, 4]; // right
var two = [true ? ...item : 4]; // error: Expected an identifier