代码运行结果显示最后的几个函数体未定义：trangle() is undefined,要怎么改，遇到类似的问题该怎么改正？

Question

class Trangle{
 double sideA,sideB,sideC,area,length;
 boolean boo;
 public Trangle(double a,double b,double c)
 {
  
   this.sideA=a;
         this.sideB=b;
         this.sideC=c;
  
 if(this.sideA+this.sideB>this.sideC&&this.sideA+this.sideC>this.sideB&&this.sideB+this.sideC>this.sideA)
 {
  this.boo=true;
  
 }
 else
 {
  this.boo=false;
  
 }
 return boo;
 
}
public double getLength(){
  if(this.sideA+this.sideB>this.sideC&&this.sideA+this.sideC>this.sideB&&this.sideB+this.sideC>this.sideA)
  {
   double p=(sideA+sideB+sideC)/2.0;
   area=Math.sqrt(p*(p-sideA)*(p-sideB)*(p-sideC));
   return area;
   
  }
  else
  {
   System.out.println("不是一个三角形，不能计算面积");
   return 0;
  }
  
 }
public void setABC(double a,double b,double c)
{
 this.sideA=a;
    this.sideB=b;
    this.sideC=c;
    if(this.sideA+this.sideB>this.sideC&&this.sideA+this.sideC>this.sideB&&this.sideB+this.sideC>this.sideA)
    { 
     this.boo=true;
    }
    else
    {
     this.boo=false;
    }
 
  }
}
class Lader{
 double above,bottom,height,area;
 Lader(double a,double b,double h)
 {
  this.above=a;
  this.bottom=b;
  this.height=h;
  
 }
public double getArea(){
  this.area=(this.above+this.bottom)*this.height/2;
  return this.area;
 }
 
}
 
public class AreaAndLength {
 public static void main(String[] args)
 {
double length,area;
Trangle trangle=null;
Lader lader;
trangle=new Trangle();
lader=new Lader();
length=trangle.getLength();
System.out.println("三角形的周长："+length);
area=trangle.getArea();
System.out.println("三角形的面积："+area);
area=lader.getArea();
System.out.println("梯形的面积："+area);
trangle.setABC(12,34,1);
area=trangle.getArea();
System.out.println("三角形的面积："+area);
length=trangle.getLength();
System.out.println("三角形的周长："+length);
}
}class Trangle{
 double sideA,sideB,sideC,area,length;
 boolean boo;
 public Trangle(double a,double b,double c)
 {
  
   this.sideA=a;
         this.sideB=b;
         this.sideC=c;
  
 if(this.sideA+this.sideB>this.sideC&&this.sideA+this.sideC>this.sideB&&this.sideB+this.sideC>this.sideA)
 {
  this.boo=true;
  
 }
 else
 {
  this.boo=false;
  
 }
 return boo;
 
}
public double getLength(){
  if(this.sideA+this.sideB>this.sideC&&this.sideA+this.sideC>this.sideB&&this.sideB+this.sideC>this.sideA)
  {
   double p=(sideA+sideB+sideC)/2.0;
   area=Math.sqrt(p*(p-sideA)*(p-sideB)*(p-sideC));
   return area;
   
  }
  else
  {
   System.out.println("不是一个三角形，不能计算面积");
   return 0;
  }
  
 }
public void setABC(double a,double b,double c)
{
 this.sideA=a;
    this.sideB=b;
    this.sideC=c;
    if(this.sideA+this.sideB>this.sideC&&this.sideA+this.sideC>this.sideB&&this.sideB+this.sideC>this.sideA)
    { 
     this.boo=true;
    }
    else
    {
     this.boo=false;
    }
 
  }
}
class Lader{
 double above,bottom,height,area;
 Lader(double a,double b,double h)
 {
  this.above=a;
  this.bottom=b;
  this.height=h;
  
 }
public double getArea(){
  this.area=(this.above+this.bottom)*this.height/2;
  return this.area;
 }
 
}
 
public class AreaAndLength {
 public static void main(String[] args)
 {
double length,area;
Trangle trangle=null;
Lader lader;
trangle=new Trangle();
lader=new Lader();
length=trangle.getLength();
System.out.println("三角形的周长："+length);
area=trangle.getArea();
System.out.println("三角形的面积："+area);
area=lader.getArea();
System.out.println("梯形的面积："+area);
trangle.setABC(12,34,1);
area=trangle.getArea();
System.out.println("三角形的面积："+area);
length=trangle.getLength();
System.out.println("三角形的周长："+length);
}
}

Answer 1

查看编译器的报错提示 查找代码的错误Trangle和Lader两个类中有构造方法 需要传入参数才可以：trangle=new Trangle(1.0,2.0,3.0);lader=new Lader(1.0,2.0,3.0);getArea你定义在Lader类中了 但却在trangle对象上调用的 当然找不到