Does anybody know what is causing errors i this code

class grades{
public static void main(String args[]){
double grade = Double.valueOf(args[0]);
String letterg;
{letterg = "F";}
else if((grade>0)&&grade<0.5)
{letterg = "D-";}

else if(((grade)=>0.5)&&grade<1.0)
{letterg = "D";}
else if((grade=>1.0)&&grade<1.5)
{letterg = "D+";}
else if((grade>1.5)&&grade<2.0)
{letterg = "C-";}
else if(grade==2.0)
{letterg = "C";}
else if((grade>2.0)&&grade<2.5)
{letterg = "C+";}
else if((grade=>2.5)&&grade<3.0)
{letterg = "B-";}
else if(grade==3.0)
{letterg = "B";}
else if((grade>3.0)&&grade<3.5))
{letterg = "B+";}
else if((grade=>3.5)&&grade<4.0)
{letter ="A";}
{letter ="Invalid number!"}

System.out.println("Your grade is"+letter);


Whenever i try to complie this I get: illegal start of expression
else if(((grade)=>0.5)&&grade<1.0)
^ ')' expected
System.out.println("Your grade is"+letter);