输入某年某月某日，判断这一天是这一年的第几天(java)

//输入某年某月某日，判断这一天是这一年的第几天
public class TianShu{
public static void main(String[] args){
TianShu t = new TianShu();
t.t1(2009,3,2);
}
public void t1(int year,int month,int day){
int sum = 0;
if(month>0){
sum += day;
}
if(month>1){
sum += 31;
}
if(month>2){
if(runNian(year)){
sum += 29;
}else{
sum += 28;
}
}
if(month>3){
sum += 31;
}
if(month>4){
sum += 30;
}
if(month>5){
sum += 31;
}
if(month>6){
sum += 30;
}
if(month>7){
sum += 31;
}
if(month>8){
sum += 31;
}
if(month>9){
sum += 30;
}
if(month>10){
sum += 31;
}
if(month>11){
sum += 30;
}
System.out.println("sum==="+sum);
}
public boolean runNian(int year){
if(year%100==0){
if((year/100)%4==0){
return true;
}
}else if(year%4==0){
return true;
}
return false;
}
}