Java - float type and integral types cast

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Introduction

The value of all integral types (int, long, byte, short, and char) can be assigned to float data type without using an explicit cast. 

int num1 = 15123; 
float salary = num1;            // Ok. int variable to float 
salary = 12455;                 // Ok. int literal to float 
float bigNum = 1226L;                 // Ok, a long literal to float 
float justAChar = 'A';          // Ok. Assigns 65.0F to justAChar

A float value must be cast before assigning to integral data type. 

  
int num1 = 10; 
float salary = 10.0F; 
num1 =  salary;      // An error. Cannot assign float to int 
num1 = (int)salary;  // Ok

float point numbers approximation

Most floating-point numbers are approximation of their corresponding real numbers.

The assignment of int and long to float may result in loss of precision. 

int num1 = 1999999999; // Stores an integer in num1 
float num2 = num1;     // Assigns the value stored in num1 to num2 
int num3 = (int)num2;  // Assigns the value stored in num2 to num3

num1 and num3 are different.

Demo

public class Main {
  public static void main(String[] args) {
    int num1 = 1999999999; // Stores an integer in num1 
    float num2 = num1;     // Assigns the value stored in num1 to num2 
    int num3 = (int)num2;  // Assigns the value stored in num2 to num3 
  
    System.out.println(num1);/*from   w ww.j  a  va2  s .com*/
    System.out.println(num2);
    System.out.println(num3);
  }
}

Result