Question

Im wondering how can I read a variable from one class’s to another?

I have two class’s, triangle.java and screen.java

in triangle.java I have: public double bound=0;

how to I read that variable in Screen.java?

triangle.java:

public class triangle extends Activity
{

public EditText txtbound;
public double bound = 0;

txtbound = (EditText)findViewById(R.id.txtbound);

public double calculate()
{
    bound=Double.parseDouble(txtbound.getText().toString());

    // do maths here

}
}

and Screen.java has:

double bound1 = triangle.bound;   

this doesnt work, how to I get the variable in Screen.java? thanks!

Answer 1

make bound1 private in Screen class like

private double bound1; //do not initialize fields here

Use getters/setters in Screen like

    public double getBound() {
      return bound1;
    }

    public void setBound(double bound1) {
        this.bound1 = bound1;
    }

In Triangle acquire instance of Screen:

Screen scr = new Screen();
scr.setBound(this.bound); --> this way the bound1 in Screen will have the value of bound from Triangle

It’s a convention to name your classes starting with capital letters.
You also don’t have to initialize your class fields when declaring them. Better
use constructors for that.
I suggest you read this tutorial to get more familiar with classes, fields and variables. Will save you time in the long run.