【java学习记录】1.设计一个能在英尺制和米制之间转换的Length类，并在TestLength类中测试

Length类： 

public class Length {
double num;
String unit;
Length(double num,String unit){//初始化
this.num=num;
this.unit=unit;
}

Length(){}

Length meter(Length l){//米转化为英尺
Length l1=new Length();
l1.num=3.28*l.num;
l1.unit="英尺";
return l1;
}

Length foot(Length l){//英尺转化为米
Length l2=new Length();
l2.num=0.305*l.num;
l2.unit="米";
return l2;
}


}

TestLength类： 

public class TestLength {

public static void main(String[] args){
Length l1=new Length(4,"米");
Length l2=new Length(2,"英尺");

//System.out.print("l1="+l1.num+" "+l1.unit+"\n");
//System.out.print("l2="+l2.num+" "+l2.unit+"\n");


//DecimalFormat df = new DecimalFormat( "0.000");//使输出的数值保留小数点后三位

Length l3=l1.meter(l1);//米转换为英尺
Length l4=l2.foot(l2);//英尺转换为米

System.out.print("l1="+l1.num+" "+l1.unit+"="+l3.num+" "+l3.unit+"\n");
System.out.print("l2="+l2.num+" "+l2.unit+"="+l4.num+" "+l4.unit+"\n");
}
}