Why is everything static?

Question

Hey
I'm trying to split some code from 1 class into a couple other classes.. not adding any new functions just moving it around so my classes have a better overview
now while trying to do that I moved some code.. figured I don't have the same buttons and ints and stuff so I moved some of those which I don't need in the other class anymore
some I need everywhere though.. so I figured I should make them public instead of private.. but now I can't use them because "Cannot make a static reference to the non-static field Main.rechtsonder " while the button isn't declared as static..
and I have that for quite a few things.. so I was wondering what the hell is static and why are those things static?

Answer 1

A static field or a static method is a member of a class that still the same for all the instances of that class.
Try to compile and run the following code:
public class Example {
     private String privateStringField;
     private Integer privateIntegerField;
     private static String sharedField ="SHARED";
     public Example(String privateStringField, Integer privateIntegerField) {
          super();
          this.privateStringField = privateStringField;
          this.privateIntegerField = privateIntegerField;
     public String toString() {
          StringBuffer toreturn = new StringBuffer("privateStringField: "+privateStringField);
          toreturn.append("\n");
          toreturn.append("privateIntegerField: " + privateIntegerField);
          toreturn.append("\n");
          toreturn.append("sharedField: " + sharedField);          
          return toreturn.toString();
     public static String getSharedField() {
          return sharedField;
     public Integer getPrivateIntegerField() {
          return privateIntegerField;
     public void setPrivateIntegerField(Integer privateIntegerField) {
          this.privateIntegerField = privateIntegerField;
     public String getPrivateStringField() {
          return privateStringField;
     public void setPrivateStringField(String privateStringField) {
          this.privateStringField = privateStringField;
     public static void setSharedField(String sharedField) {
          Example.sharedField = sharedField;
     public static void main(String[] args) {
          Example one = new Example("one",new Integer(1));
          Example two = new Example("two",new Integer(2));
          System.out.println(one);
          System.out.println(two);
          System.out.println("");
          one.setPrivateIntegerField(new Integer(100));
          one.setSharedField("SHARED modified by one");
          System.out.println(one);
          System.out.println(two);
          System.out.println("");
          System.exit(0);
}