JAVA
S.PPrimitive and reference types
The new keyword
In most cases, an object of a reference type can be created using the new
keyword.
String language = new String("java");
Comparisons
So, you do not need to use comparison operators when you want to compare the values. The correct way to compare content is to invoke the special method equals
.
String s1 = new String("java");
String s2 = new String("java");
String s3 = s2;
System.out.println(s1.equals(s2)); // true
System.out.println(s2.equals(s3)); // true
Array
In Java, an array has the following important features:
- an array is a reference type;
- all array's elements are stored in the memory sequentially ;
- each element of the array is accessed by its numerical index, the first element has the index 0;
- the last element is accessed by the index equal to array size - 1;
- it is possible to create an array to store elements of any type.
int[] array; // declaration's form 1
int[] numbers = { 1, 2, 3, 4 }; // an array of 1, 2, 3,
int n = ...; // n is a length of an array