unicode 转汉字

public class TestUnicode {
public static void main(String[] args) throws Exception {
String str = "\\U5728\\U4e00\\U500b\\U6674\\U6717\\U7684\\U591c\\U665a\\Uff0c\\U6708\\U4eae\\U53c8\\U5713\\U53c8\\U5927\\U639b\\U5728\\U591c\\U7a7a\\U4e2d\\U3002";
//System.out.println(new JSONTokener("'"+str+"'").nextValue().toString());
str.trim();
String strArr[] = str.split("\\\\U");

System.out.print(strArr.length);
// System.out.println((char)Integer.parseInt("6717",16));

for (int i = 0;i<strArr.length;i++) {
//System.out.println(strArr[i]);
if (strArr[i]!=null && !strArr[i].equals("")) {
System.out.print((char)Integer.parseInt(strArr[i],16));
}
}
//System.out.println(UnicodeCover(str));
}

public static String UnicodeCover(String str){
String string = String.valueOf((char)Integer.parseInt(str,16));
return string;
}
}


NumberNotfromatException:
For input string ""
空字符串“”不能转换为数字