Java toString() method with Examples

Java toString() method with Examples

We can use this method to get the string representation of an object.

The Objects can be Integer, Long, Double, Boolean, Custom An object like String.

 Whenever we are trying to print any object reference internally toString() method will be executed. If our class doesn't contain the toString() method then the Object class toString() method will be executed.

 Every class in java is the child of the Object class either directly or indirectly.

 Object class contains toString() method.

 Syntax:

  
   public String toString()
  {
        return getClass().getName()+"@"+Integer.toHexString(hashCode());
  }
   
    

  
   
   public class Student {
      int roll;
      String name;
      int age;
      String college;
      String dob;
      String address;
      Student(int roll, String name, int age, String college, String dob, String address) {
          this.roll = roll;
          this.name = name;
          this.age = age;
          this.college = college;
          this.dob = dob;
          this.address = address;
      }
     public static void main(String[] args)
      {
          Student student =
          new Student(10011,"Sara K", 21, "COEP", "12-01-2021", "Pune");
          System.out.println(student);
          System.out.println(student.toString());
      }
    
  }
  
  output:
  Student@2a139a55
  Student@2a139a55
    

In the above program Object class toString() method got executed which is implemented as follows.

  
  public String toString() {
      return getClass().getName() + "@" + Integer.toHexString(hashCode());
      }
      
  here  getClass().getName()  =>  classname@hexa_decimal_String_representation_of_hashCode  
   
    

To provide our own String representation we have to override toString() method in our class.

  
   
   public  String  toString(){
  return name+"........"+rollno;
  }
  
  ....
  
  
  
  public String toString()
      {
          return " roll:" + roll +" name:" + name+ " age: " + age + " college: " + college + " dob:  " + dob + " address: " + address;
      }
    

  
   public class Student {
      int roll;
      String name;
      int age;
      String college;
      String dob;
      String address;
      Student(int roll, String name, int age, String college, String dob, String address) {
          this.roll = roll;
          this.name = name;
          this.age = age;
          this.college = college;
          this.dob = dob;
          this.address = address;
      }
      public String toString() {
          return " roll:" + roll + " name:" + name + " age:" + age + " college:" + college + " dob:" + dob + " address: " + address;
      }
      public static void Student(String[] args) {
          Student student = new Student(10011, "Sara K", 21, "COEP", "12-01-2021", "Pune");
          System.out.println(student);
  
      }
  
  }
  output:
  roll:10011 name:Sara K age:21 college:COEP dob:12-01-2021 address: Pune
   

In String class, StringBuffer, StringBuffer, wrapper classes and in all collection classes toString() method is overridden for meaningful string representation. Hence in our classes also highly recommended overriding the toString() method.

  
    public class ToStringTest {
        public String toString() {
            return "Hello World";
        }
        public static void main(String[] args) {
            Integer i = new Integer(101);
            String s = new String("Sara");
            float f = new Float(11.0);
            ToStringTest toStringTest = new ToStringTest();
            System.out.println(i);
            System.out.println(s);
            System.out.println(f);
            System.out.println(toStringTest);
    
        }
    }
 output:
$javac ToStringTest.java
$java -Xmx128M -Xms16M ToStringTest
101
Sara
11.0
Hello World 

Case:1

We can use the toString() method to convert wrapper object (or) primitive to String.

public String toString(); 

1. Every wrapper class (including Character class) contains the above toString() method to convert the wrap String.

 2. It is the overriding version of the Object class toString() method. 

3. Whenever we are trying to print wrapper object reference internally this toString() method only executed.

Example:

 
    class WrapperClassDemo {
    public static void main(String[] args) {
    Integer i=Integer.valueOf("10");
    System.out.println(i);//10
    System.out.println(i.toString());//10
    }
    } 

Case:2

Every wrapper class contains a static toString() method to convert primitive to String.

 public static String toString(primitive p);

     
    class WrapperClassDemo {
    public static void main(String[] args)
    String s1=Integer.toString(10);
    String s2=Boolean.toString(true);
    String s3=Character.toString('a');
    System.out.println(s1); //10
    System.out.println(s2); //true
    System.out.println(s3); //a
    }
    } 

Integer and Long classes contain the following static toString() method to convert the primitive to specific String form.

public static String toString(primitive p, int radix); Example:

           
            class WrapperClassDemo {
            public static void main(String[] args)
            String s1=Integer.toString(7,2);
            String s2=Integer.toString(17,2);
            System.out.println(s1);//111
            System.out.println(s2);//10001
            }
            } 

Dancing between String, wrapper object, and primitive

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In this article, we have seen the Java toString() method with Examples.