java程序题

public static void main(String[] args) {
boolean flag=true;
String content=null;
while(flag){
Scanner scanner = new Scanner(System.in);
Double num;
if(scanner.hasNextDouble()){
num = scanner.nextDouble();
System.out.println("第一题"+numberFormat(Math.abs(num),2));
if(num<0){
System.out.println("第二题：input error");
}else{
System.out.println("第二题："+num+"的平方根是："+Math.sqrt(num));
}
}else{
content = scanner.next();
if("break".equals(content)){
break;
}
}
}
}
public static String numberFormat(Number num,int digit){
NumberFormat numberFormat = NumberFormat.getInstance();
numberFormat.setMaximumFractionDigits(digit);
numberFormat.setMinimumFractionDigits(digit);
String result = numberFormat.format(num);
return result;
}

public static String getNum(double doubleNum){
double tempDou = Math.abs(doubleNum);
NumberFormat nf = NumberFormat.getInstance();
nf.setMaximumFractionDigits(2);
return nf.format(tempDou);

}

public static String getNumSqr(double doubleNum){
if(doubleNum<0){
return "error";
}
double tempDou = Math.sqrt(doubleNum);
NumberFormat nf = NumberFormat.getInstance();
nf.setMaximumFractionDigits(3);
return nf.format(tempDou);

}本回答被提问者和网友采纳

Math类中有一个方法 叫abs（）
括号里面可以传入你要求绝对值的参数，
比如 你要求 -5的绝对值 可以这样写
Math.abs(-5);