Thanks to those that helped me get this far. I made some changes. Now there is an error on the line where array1 is assigned in the method, Method(). (edited version show below)
public class JavaApplication2 {
int[] array1;
public JavaApplication2()
{
}
public static void main(String[] args) {
JavaApplication2 obj = new JavaApplication2();
obj.method();
System.out.print(obj.array1[1]);
}
public void method()
{
array1 = {1,1,1,1,1,1};
}
}
Do this:
public class JavaApplication2 {
int array[];
public static void main(String[] args) {
JavaApplication2 obj = new JavaApplication2();
obj.method();
System.out.print(obj.array[1]);
}
public void method() {
array = new int[]{1,1,1,1,1,1};
}
}
You declarated an array in the constructor of the class and one in the method() method. These are local variables which are only accessible in that particular method/constructor. You need to specify an instance variable which can be accessed in the way you tried.
They are defined within the same class; however they are declared within methods so they are local variables. This means they only exist within their respective methods and in particular only for a single invocation of the method. Essentially they disappear when the method exits and are recreated anew each time the method is called.
To quote the tutorial:
- Local Variables Similar to how an object stores its state in fields, a method will often store its temporary state in local variables. The syntax for declaring a local variable is similar to declaring a field (for example, int count = 0;). There is no special keyword designating a variable as local; that determination comes entirely from the location in which the variable is declared — which is between the opening and closing braces of a method. As such, local variables are only visible to the methods in which they are declared; they are not accessible from the rest of the class.
You probably mean for them to be fields (also called instance variables), which means that each instantiated object of the class has their own 'personal' variable which persists along with the object that 'owns' it. Fields are declared inside the class but outside a method.
public class JavaApplication2 {
int[] array1; // variable declaration
// begins with the type of the variable
public JavaApplication2() {}
public void method() {
array1 = {1,1,1,1,1,1}; // assignment
} // begins with an identifier
}
Typically fields are initialized once during the constructor so you don't have to call a separate method to do so.
public class JavaApplication2 {
int[] array1;
public JavaApplication2() {
array1 = {1,1,1,1,1,1};
}
}
You need to create array1 as a class variable in order for the whole class to have access to it. As a general rule of thumb, the scope of a variable last between the two brackets { } it is initialized in. In your two methods, you initialize array1 in those method, so the scope of array1 is in those methods only.
Change the code to something like this:
public class JavaApplication2 {
int[] array1;
public JavaApplication2()
{
}
public static void main(String[] args) {
JavaApplication2 obj = new JavaApplication2();
obj.method();
System.out.print(obj.array1[1]);
}
public void method()
{
array1 = new int[]{1, 1, 1, 1, 1};
}
}
It would be even better to initalize array1[] as private and have a getter method for it like this:
public class JavaApplication2 {
private int[] array1;
public JavaApplication2()
{
}
public static void main(String[] args) {
JavaApplication2 obj = new JavaApplication2();
obj.method();
System.out.print(obj.getArray1().[1]);
}
public void method()
{
array1 = new int[]{1, 1, 1, 1, 1};
}
public void getArray1()
{
return array1;
}
}
Because it's null, you didn't initialize it. Inside Method you are initializing other array, not what you are asking for.
