eclipse的java編輯工具

偶爾使用Jcreator時出現"Exception in thread "main" java.lang.NoSuchMethodError： main"。
但是使用cmd直接編輯後執行沒有問題。
關掉Jcreator再編輯執行一次就正常，讓我想換Java編輯工具了。
網路上大部份推薦eclipse，官網http://www.eclipse.org/
下載後解壓縮就可使用。
第一次使用要建新Java Project。jdk路徑它有預設的(Java-SE1.6)，也可自已指定(jdk-1.6.0_22)

//////自已亂寫///////請勿參考哈////////
=====Circle.java=================
package nvoms123;

public class Circle {
public static void main(String args[]){
FindArea1 obj1 = new FindArea1(3);
double Carea2 = obj1.getCarea1();
System.out.println("圓面積"+Carea2);
FindArea2 obj2 = new FindArea2(3.0,4.0);
double Carea3 = obj2.getCarea2();
System.out.println("矩形面積"+Carea3);
FindArea3 obj3 = new FindArea3(3.0,4.0,5.0);
double Carea4 = obj3.getCarea3();
System.out.println("梯形面積"+Carea4);
}
}
//設定方法就一定有回傳值，不然要設定void不回傳


=========FindArea1.java===================
package nvoms123;

class FindArea1 {
private double radius;
public FindArea1(double r){radius=r;}
public void setRRRRR(double r){radius=r;}

public double getCarea1(){
return (radius*radius*3.14159);
}
}
=========FindArea2.java===================
package nvoms123;

class FindArea2 {
private double length,width;
public FindArea2(double l,double w){length=l;width=w;}
public void setRRRRR(double l,double w){length=l;width=w;}

public double getCarea2(){
return (length*width);
}
}
=========FindArea3.java===================
package nvoms123;

class FindArea3 {
private double up,downline,high;
public FindArea3(double u,double d,double h){up=u;downline=d;high=h;}
public void setRRRRR(double u,double d,double h){up=u;downline=d;high=h;}

public double getCarea3(){
return ((up+downline)*high)/2;
}
}
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