Strings and Object References in Java

9. Class String

Answer:
The variables and methods of a class will be documented somewhere.

Class `String`

Use Google or another search engine to find documentation for class String. Search for Java String.

Here is a short version of the documentation for String.

 // Constructors
    public String(); 
    public String(String  value); 

    // Methods
    public char charAt(int  index);
    public String concat(String  str); 
    public boolean endsWith(String  suffix); 
    public boolean equals(Object  anObject); 
    public boolean equalsIgnoreCase(String  anotherString); 
    public int indexOf(int  ch); 
    public int indexOf(String  str); 
                       
    public int length(); 
    public boolean startsWith(String  prefix); 
    public String substring(int  beginIndex ); 
    public String substring(int  beginIndex, int endIndex); 
    public String toLowerCase(); 
    public String toUpperCase(); 
    public String trim();

The documentation first lists constructors. Then it describes the methods. For example,

public String concat(String  str); 
--+--- --+---  --+--  ----+----
  |      |       |        |
  |      |       |        |
  |      |       |        +---- says that the method requires a
  |      |       |              String reference parameter
  |      |       |
  |      |       +----- the name of the method
  |      |
  |      +----- the method returns a reference 
  |             to a new String object
  |
  +----- anywhere you have a String object, 
         you can use this method

public will be explained in greater detail in another chapter.

Question 9:
Is the following code correct?
String first = "Red " ;
String last  = "Rose" ;
String name  = first.concat( last );
You don't have to know what concat() does (yet); look at the documentation and see 
 if all the types are correct.