Here is a simple Java code to sum up two numbers:

```java
public class SumNumbers {
    public static void main(String[] args) {
        int num1 = 5;
        int num2 = 10;
        int sum = num1 + num2;
        
        System.out.println("The sum of " + num1 + " and " + num2 + " is: " + sum);
    }
}
```

In this code, we have two variables `num1` and `num2` with values 5 and 10 respectively. We then add these two numbers and store the result in the `sum` variable. Finally, we print out the sum of the two numbers.
int součet = a + b;
System.out.println(součet);