# Learn for the first time java # 3 expressions and operators

## What is a formula?

```
public class Main {
public static void main(String[] args) {
int a;
int b;
a = 20;
b =a+5;
System.out.println(a);
System.out.println(b);
}
}
```

Execution result

```
20
25
```

Something like the 6th line is called an expression.
"A", "b" and "5" are called operands, and "+" and "*" are called operators.
Even if it is a complicated formula, all the formulas consist of these two.

### literal

Among operants, what is described in the source code such as "5" and "hello, world" is called a literal.
Literals have data types such as (int).

### Escape sequence

A special character is represented by a description method that is described by the \ symbol followed by a single character.

Notation |
meaning |

￥” |
Double quote symbol |

¥ ’ |
Quote symbol |

￥￥ |
Yen sign |

￥ｎ |
new line |

### operator

operator |
function |

＋ |
addition |

- |
subtraction |

＊ |
multiplication |

／ |
division |

％ |
Remainder of division (remainder) |

＋ |
String concatenation |

＝ |
Substitute the right side for the left side |

＋＝ |
Add the left side and the right side and assign to the left side (as per the arithmetic operator) |

＋＋ |
Increase the value by one |

--- |
Decrease the value by one |