Java Assignment Operators
Assignment operators put values into variables. The plain equals sign is the one you use most, but Java also offers a family of compound operators that update a variable using its current value, keeping your code short and clear.
The basic assignment operator
The single equals sign takes the value on its right and stores it in the variable on its left. It is important not to confuse this with the double equals used for comparison; a single = always means assign, never compare.
Assigning and reassigning
public class Main {
public static void main(String[] args) {
int level = 1; // store 1 in level
level = 5; // replace it with 5
level = level + 2; // read level (5), add 2, store back 7
System.out.println(level); // 7
}
}Compound assignment operators
Writing level = level + 2 is a little repetitive. Java lets you shorten it to level += 2. Every arithmetic operator has a compound partner that does the maths and stores the result in one step.
Compound operators in practice
Watch how a single variable changes as we apply several compound operators in a row. Each one uses the current value of total to produce the next value.
Updating a running total
public class Main {
public static void main(String[] args) {
int total = 10;
total += 5; // 15
total -= 3; // 12
total *= 2; // 24
total /= 4; // 6
System.out.println(total); // 6
}
}Building a string with +=
public class Main {
public static void main(String[] args) {
String message = "Java";
message += " is";
message += " fun";
System.out.println(message); // Java is fun
}
}
