java to String method

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Java to String () method

If you want to represent any object as a string, to String () method comes into existence.

The two String () method returns the string representation of the object.

If you print any object, java compiler internally invokes the two String () method on the object. So overriding the two String () method, returns the desired output, it can be the state of an object etc. depends on your implementation.

Advantage of Java to String () method

By overriding the two String () method of the Object class, we can return values of the object, so we don't need to write much code.

Understanding problem without to String () method

Let's see the simple code that prints reference.

  1. class Student{  
  2.  int rollno;  
  3.  String name;  
  4.  String city;  
  5.   
  6.  Student(int rollno, String name, String city){  
  7.  this.rollno=rollno;  
  8.  this.name=name;  
  9.  this.city=city;  
  10.  }  
  11.   
  12.  public static void main(String args[]){  
  13.    Student s1=new Student(101,"Raj","lucknow");  
  14.    Student s2=new Student(102,"Vijay","ghaziabad");  
  15.      
  16.    System.out.println(s1);//compiler writes here s1.toString()  
  17.    System.out.println(s2);//compiler writes here s2.toString()  
  18.  }  
  19. }  
Output:Student@1fee6fc
       Student@1eed786

 

As you can see in the above example, printing s1 and s2 prints the hash code values of the objects but I want to print the values of these objects. Since java compiler internally calls to String () method, overriding this method will return the specified values. Let's understand it with the example given below:

Example of Java to String () method

Now let's see the real example of to String () method.

  1. class Student{  
  2.  int rollno;  
  3.  String name;  
  4.  String city;  
  5.   
  6.  Student(int rollno, String name, String city){  
  7.  this.rollno=rollno;  
  8.  this.name=name;  
  9.  this.city=city;  
  10.  }  
  11.    
  12.  public String toString(){//overriding the toString() method  
  13.   return rollno+" "+name+" "+city;  
  14.  }  
  15.  public static void main(String args[]){  
  16.    Student s1=new Student(101,"Raj","lucknow");  
  17.    Student s2=new Student(102,"Vijay","ghaziabad");  
  18.      
  19.    System.out.println(s1);//compiler writes here s1.toString()  
  20.    System.out.println(s2);//compiler writes here s2.toString()  
  21.  }  
  22. }  
download this example of toString method
Output:101 Raj lucknow
       102 Vijay ghaziabad