有没有办法循环变量名称？

Question

So for example I have the following variables: Var1, Var2, Var3, Var4, Var5 - a total of 5 variables. All with unique data and I want to loop though them using a for loop.

//String Var1 = something, Var2 = something etc..
for (int i = 1; i <= 5; i++)
{
Var(i) = "something else";
}
//i.e I change Var(1), Var(2) etc.. to something else respectively.

To clarify further, ultimately I want to apply this method to iterate through multiple components in my program. I have a large number of components with styled names(eg label1, label2, label3 etc..) and want to change the value of these components without having to individually set their value.

Answer 1

You can do it with reflection, if the variables are defined as members of a class. For method parameters or local variables it is not possible. Something similar to this:

Class currentClass = getClass();
Field[] fields = currentClass.getFields();
for (Field f : fields) {
  System.out.println(f.getName());
}

If you intend to change the value it becomes a bit more complicated as you also have to consider the type of the variable. Eg you can assign a String to a variable of type Object but not the other way around.

Answer 2

I would suggest to go for an array if data type of variables are same. You can try something like that

        String[] Var = {"something","something2","something else"};
        for (String var : Var)
        {
        System.out.println(var);
        }

Answer 3

You can't loop through (local) variables. You can use an array or a List and then loop through its elements:

for (Object item : myListOfObjects) {
    // do the processing
}

Answer 4

Using Java 8 Arrays it is as simple as:

Arrays.stream(varArray).forEach(System.out::println);

Usage:

public class LoopVariables {
    public static void main(String[] args) {
        String[] varArray = new String[]{"Var1", "Var2", "Var3", "Var4", "Var5"};
        Arrays.stream(varArray).forEach(System.out::println);
    }
}

Answer 5

As long as all the variables use the same type, you can use an Array to store all of them. Then you can use a for loop to iterate through the array. Something like this:

     String[] V = {"var1","var2","var3","var4","var5"};
    int arraylength = V.length;

    for(int i = 0; i<arraylength; i++){
        System.out.println(V[i]);
    }

Answer 6

Try This piece of Code.

public class Main {

    public static void main(String[] args) {
        Insan i1[]=new Insan[5];
        i1[0].name="Ali";
        i1[0].age=19;
        i1[1].name="Pakize";
        i1[1].age=29;
        i1[2].name="Kojiro Hyuga";
        i1[2].age=30;
        i1[3].name="Optimus Prime";
        i1[3].age=40;
        for (int ib=0; ib < 4; ib++) {
            System.out.println("Name: " + i1[ib].name + " Age: "+i1[ib].age);
        }

    }
}