如何使用另一类的方法？ （从Processing导出的android项目）

Question

My project is an exported android project from Processing. It uses Fontastic library. It always force closes whenever I try to run it on my Android device. I was thinking that its because of the font.setup() on the MainActivity but I can not think of any solution. Please take a look on the following lines of code. Thank you.

This is the MainActivity.java

import android.app.Activity;
import android.os.Bundle;   

public class MainActivity extends Activity {
public static Wave font;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    font.setup();
}
}

and this is the class named Wave.java

import fontastic.FPoint;
import fontastic.Fontastic;
import processing.core.PApplet;
import processing.core.PFont;

public class Wave extends PApplet {
    Fontastic f;
    float charWidth = 512;
    PFont myFont;
    int version = 0;
    boolean fontBuilt = false;

    public void setup(){
        randomize();
        create();
    }

    public void randomize(){
        version++;
        if (f != null) { f.cleanup(); }
        f = new Fontastic(this, "WaveFont" + nf(version,4));
        f.setAdvanceWidth(PApplet.parseInt(charWidth));
        for (int i=0; i<Fontastic.alphabet.length; i++) {
            char c = Fontastic.alphabet[i];
            FPoint[] points = new FPoint[4];
            float rectSize = charWidth * 0.5f;
            float rnd = charWidth * 0.2f;
            points[0] = new FPoint(charWidth / 2 - rectSize / 2, charWidth / 2 - rectSize / 2);
            points[1] = new FPoint(charWidth / 2 - rectSize / 2, charWidth / 2 + rectSize / 2);
            points[2] = new FPoint(charWidth / 2 + rectSize / 2, charWidth / 2 + rectSize / 2);
            points[3] = new FPoint(charWidth / 2 + rectSize / 2, charWidth / 2 - rectSize / 2);
            points[0].setControlPoint1(points[0].x + rnd, points[0].y + random(-rnd, rnd));
            points[1].setControlPoint1(points[1].x + random(-rnd, rnd), points[1].y - rnd);
            points[2].setControlPoint1(points[2].x - rnd, points[2].y + random(-rnd, rnd));
            points[3].setControlPoint1(points[3].x - random(-rnd, rnd), points[3].y + rnd);
            points[0].setControlPoint2(points[0].x + random(-rnd, rnd), points[0].y + rnd);
            points[1].setControlPoint2(points[1].x + rnd, points[1].y + random(-rnd, rnd));
            points[2].setControlPoint2(points[2].x + random(-rnd, rnd), points[2].y - rnd);
            points[3].setControlPoint2(points[3].x - rnd, points[3].y + random(-rnd, rnd));
            f.addGlyph(c).addContour(points);
        }
    }

    public void create(){
        f.buildFont();
        f.cleanup();
        myFont = createFont(f.getTTFfilename(), 200);
        fontBuilt = true;
    }
}

Answer 1

You need to create an object of the class whose method you want to use. If you don't do that you will get NullPointerException because the variable font is not initialized.

Do this

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    font = new Wave(); // You missed this line
    font.setup();
}