some useful piece of code in Java

gistfile1.txt

1.Get the max and min number in the array of numbers
  var arr = [1, 2, 3, 4, 5];
  var max = Math.max.apply(Math, arr);
  var min = Math.min.apply(Math, arr);
  
2.Empty the array
  var arr = [1, 2, 3];
  arr.length = 0;
  
3.Don't use delete to move an item in the array
  Use splice instead of using delete to delete an item 
  from an array. Using delete replaces the item with 
  undefined instead of the removing it from the array.
  var arr = [1, 2, 3, 4, 5, 6];
  arr.length;
  arr.splice(3, 1);
  
4.Use the map() function method to loop through an array’s items
  var squars = [1, 2, 3].map(function(val) {
    return val * val;
  });
  
5.Check the properties of an object when using a for-in loop
  var obj = {/***/};
  for(var p in obj) {
    if(obj.hasOwnProperty(p)) {
      //do something with p
    }
  }
  
6.Create an object whose prototype is a given object
  function clone(object) {
    function Constructor() {
    }
    Constructor.prototype = object;
    return new Constructor();
  }