Java Object-Oriented foundation string class

Two ways to instantiate a String class

A. Direct Assignment

public class Stringlei{public static void Main (string args[]) {string name= "Zhang San"; System.out.println ("Name:" +name);}}

B. Through the keyword new

public class Stringlei{public static void Main (string args[]) {string Name=new string ("Zhang San"); System.out.println ("Name:" +name);}}

content Comparison of string

1. Use "= =" to compare

public class Stringlei{public static void Main (string args[]) {   string  str1= "Hello";   String Str2=new string ("Hello");   String str3=str2;   System.out.println ("Str1==str2?-->" + (STR1==STR2))//false   System.out.println ("Str1==str3?-->" + (str1= =STR3)//false   System.out.println ("Str2==str3?-->" + (STR2==STR3));//true}}

It can be said that "= =" Determines whether the address space is equal to determine the address, if you want to determine the content, you must use the Equals () method provided in string to complete:

public class Stringlei{public static void Main (string args[]) {   string  str1= "Hello";   String Str2=new string ("Hello");   String str3=str2;   System.out.println ("Str1==str2?-->" + (Str1.equals (str2));//true   System.out.println ("Str1==str3?-->" + (Str1.equals (STR3))); /true   System.out.println ("Str2==str3?-->" + (Str2.equals (STR3)));//true}}

two ways to instantiate the difference

The constructor method can be completed using the direct assignment and the new call in string. Compare two methods.

A string is an anonymous object of string

public class Stringlei{public static void Main (string args[]) {   string  str1= "Hello";//actually the point of a heap memory space is given to the stack memory space   String  str2= "Hello";   String  str3= "Hello";   System.out.println ("Str1==str2?-->" + (STR1==STR2))//true   System.out.println ("Str1==str3?-->" + (str1= =STR3)//true   System.out.println ("Str2==str3?-->" + (STR2==STR3));//true}}

the contents of the string cannot be changed    

public class Stringlei{public static void Main (string args[]) {   string  str= "Hello";   str=str+ "world!";   System.out.println ("str =" +str);}}

This is not a simple change to the contents of STR, as follows:

Java Object-oriented foundation string class