angular.js - angular的ng-switch可以用true作為判斷條件嗎？-PHP中文網路問答

如何用ng-switchh實現根據數組長度不同，顯示不同的內容，假如用arr.length作為判斷條件的話需要寫很多情況，所以考慮用true作為判斷條件，但是不知道ng-switch-when 該怎麼寫，當然用ng-if也可以實現，只是對ng-switch的寫法有疑問，謝謝。
程式碼如下：

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>title</title>
    <script src="angular.js"></script>
    <style>

    </style>
</head>
<body ng-app="App">
<p ng-controller="Ctrl">
    <p ng-switch="arr.length">
        <span ng-switch-when="1">1</span>
        <span ng-switch-when="2">2</span>
        <span ng-switch-when="3">3</span>
    </p>

    <p>
        <span ng-if="arr.length<2">1---</span>
        <span ng-if="arr.length>=2">2---</span>
    </p>

    <p ng-switch=true>
        <span ng-switch-when="(arr.length==0)"> 1---true </span>
        <span ng-switch-when="(arr.length==0)"> 2---true </span>
    </p>
</p>

<script>
    var App = angular.module("App", []);
    App.controller("Ctrl", ["$scope", function ($scope) {
        $scope.arr = [1, 2,3];
    }]);
</script>
</body>

</html>