Here's a sample code for an Equation class in Java:

```java
public class Equation {
    // instance variables
    private String equation;

    // constructor
    public Equation(String equation) {
        this.equation = equation;
    }

    // methods
    public double solve() {
        // parses the equation and returns the solution
        return (double) new ScriptEngineManager().getEngineByName("JavaScript").eval(equation);
    }

    // getter and setter methods
    public String getEquation() {
        return equation;
    }

    public void setEquation(String equation) {
        this.equation = equation;
    }
}
```
Implementa una classe per &quot;Equazioni&quot;. Ciò significa tutti i tipi di equazioni matematiche. Scrivilo in Java.