Java限制长度整数

Question

I am new in Java and I need some help.

Can someone tell me how I can set limit length to integer = 6 in this code.

For example

id = 124973 

public void setId(int id) {
    this.id = id;
}

Answer 1

One way to do it is like this:

public boolean checkLength(int id, int length) {
    return 0 == (int)(id / Math.pow(10, length));
}

EDIT:

As per @EliSadoff comment below, you can also do something like this:

public boolean checkLength(int id, int length) {
    return Math.log10(id) < length;
}

You can then simply call this function like this:

checkLength(123456, 6);

Answer 2

"String.valueOf(id).length()" - checks the length of a int variable, which you receive in setId method parameter.

public void setId(int id){
    if(6 >= String.valueOf(id).length())
       this.id= id;
    else
       //do something if the received id's length is greater than max
}

Answer 3

In your setId method add a check:

if (id >= 1000000 || id < 0) {
   throw new IllegalArgumentException("id must be max 6 digits and cannot be negative");
}  

Answer 4

validate the inp before assigning it

public void setId(int id){
    if(id>0 && id<=999999){
        this.id= id;
    }else{
        this.id= 0;
    }
}

Answer 5

In java numbers like int don't have the length. Although Integer is a class, there is no length() function -- see the Java docs. So, to find the length, you have to convert Integer to String using String.valueOf(Integer_value) . So, you can do like below:

Public void limit(Integer a) {
if(String.valueOf(a)<=6) {
    //do your logic
}
else {
//printout Integer length limit exceeded
}
}