java - What is wrong with my GUI program -

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import java.awt.graphics2d; import java.awt.rectangle; import java.awt.geom.point2d; import java.awt.geom.ellipse2d; import java.awt.geom.line2d;  public class car {  private int xleft; private int ytop;  public car(int x, int y){     xleft =x;     ytop=y; }  public void draw(graphics2d g2){     rectangle body = new rectangle(xleft, ytop+10, 60, 10);     ellipse2d.double fronttire= new ellipse2d.double(xleft+10, ytop+20, 10,     10);      ellipse2d.double reartire= new     ellipse2d.double(xleft+40,ytop+20,10,10);     point2d.double r1 = new point2d.double(xleft+10,ytop+10);     point2d.double r2 = new point2d.double(xleft+20,ytop);     point2d.double r3 = new point2d.double(xleft+40,ytop);     point2d.double r4 = new point2d.double(xleft+50,ytop+10);     line2d.double frontwindshield = new  line2d.double(r1,r2);     line2d.double rooftop = new  line2d.double(r2,r3);     line2d.double rearwindshield = new  line2d.double(r3,r4);      g2.draw(body);     g2.draw(fronttire);     g2.draw(reartire);     g2.draw(frontwindshield);     g2.draw(rooftop);     g2.draw(rearwindshield);  } }  import java.awt.graphics; import java.awt.graphics2d;  import javax.swing.jcomponent;  public class carcomponent extends  jcomponent { public void paintcompnent(graphics g){     graphics2d g2 = (graphics2d) g;     car car1 = new car(0,0);      int x = getwidth()-60;      int y = getheight()-30;       car car2 = new car(x,y);      car1.draw(g2);      car2.draw(g2);  } }  import javax.swing.jframe; public class carviewer {       public static void main(string[] args) {     jframe frame = new jframe();     frame.setsize(400,500);     frame.settitle("two cars");     frame.setdefaultcloseoperation(jframe.exit_on_close);      carcomponent component = new carcomponent();     frame.add(component);      frame.setvisible(true);     }   }

i have looked @ code hours, can't figure out wrong. copied right out of textbook. when hit run, empty box shows up. supposed show cars, 1 on top left, 1 on bottom right.

the method paintcomponent misspelled , not override superclass method. hence, default method draws blank box called.

there way avoid common bug down road, @override annotation. adding annotation methods either override superclass method or implement interface method, compiler stop error if mistype method name, rather creating difficult-to-debug error:

@override public void paintcomponent(graphics g){     // code here }

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