"Int Cannot Be Dereferenced" in Java

int cannot be dereferenced in Java

id is of primitive type int and not an Object. You cannot call methods on a primitive as you are doing here :

id.equals

Try replacing this:

        if (id.equals(list[pos].getItemNumber())){ //Getting error on "equals"

with

        if (id == list[pos].getItemNumber()){ //Getting error on "equals"

Int cannot be dereferenced Java

Integer.parseInt(left) - Integer.parseInt(right) is an int. An int is a primitive, so it has no methods, therefore you can't call toString() on an int value.

You can use the static Integer.toString() method instead.

For example:

return Integer.toString(Integer.parseInt(left) - Integer.parseInt(right));

int cannot be dereferenced

The g in drawString is the color value you've passed in, not your Graphics reference. So the error is when you're trying to call a method on an int, which you can't do.

//            Passing an integer 'g' into the function here |
//                                                          V
public void drawString(String str, int x, int y, int r, int g, int b){
//  | This 'g' is the integer you passed in
//  V
    g.setColor(r, g, b);
    g.drawString(str, x, y, 0);
}

Why does this error state int cannot be dereferenced for the if statement?

You have a problem here :

if (password.length() != 7){

int doesn't have length() method, not like String, if you want to check the length of the password field then you can use :

if (passwordTextField.getText().length() != 7) {

Or if you are using the password as an int, and you need to check the length of the int then use :

if (String.valueOf(password).length() != 7) {

How to solve the problem: int cannot be dereferenced

For the hashcode method, you can just leave the ints as they are. Ints are their own hascodes. For the equals method, just compare them using =. So the code becomes:

public class Connection {

    String srcAddr, dstAddr, protocol; int srcPort, dstPort;

    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + ((dstAddr == null) ? 0 : dstAddr.hashCode());
        result = prime * result + dstPort;
        result = prime * result
                + ((protocol == null) ? 0 : protocol.hashCode());
        result = prime * result + ((srcAddr == null) ? 0 : srcAddr.hashCode());
        result = prime * result + srcPort;
        return result;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        Connection other = (Connection) obj;
        if (dstAddr == null) {
            if (other.dstAddr != null)
                return false;
        } else if (!dstAddr.equals(other.dstAddr))
            return false;
        if (dstPort != other.dstPort)
            return false;
        if (protocol == null) {
            if (other.protocol != null)
                return false;
        } else if (!protocol.equals(other.protocol))
            return false;
        if (srcAddr == null) {
            if (other.srcAddr != null)
                return false;
        } else if (!srcAddr.equals(other.srcAddr))
            return false;
        if (srcPort != other.srcPort)
            return false;
        return true;
    }

}

Writing correct implementations of hashCode and equals is tricky. Better use your IDE to generate them. That's what I did here too.

Java Error: int cannot be dereferenced

x is an int, a primitive, and therefore cannot be dereferenced - meaning x.anything is invalid syntax in Java.

I'm assuming what you meant to do is assign some user input to x :

Scanner sc = new Scanner(System.in);
int x = sc.nextInt();

int cannot be dereferenced while sorting list by Integer property

int cannot be dereferenced suggest that getR() returns int not Integer (despite what your title suggests). int is primitive type so it doesn't have any methods like compareTo. Easiest way to compare int values is by Integer.compare(a, b) (by default it returns result according to ascending order, if you want to get result for descending order Integer.compare(b, a)).

So change

return lhs.getR().compareTo(rhs.getR());

to

return Integer.compare(lhs.getR(), rhs.getR());

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BTW since Java 8 we can use Lambdas and method references. Also lists now have sort(Comparator) method which allows us to write code like:

data.sort(Comparator.comparingInt(Segment::getR));

instead of

Collections.sort(data, new Comparator<Segment>() {
    @Override
    public int compare(Segment lhs, Segment rhs) {
        return Integer.compare(lhs.getR(), rhs.getR());
    }
});

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