Variable not initialized and I can't use null for booleans

Question

I'm with a little problem here probably is because I cant figure out how to use try and catch.

My method is a bit long but the problem is simple I think. I'm having the problem of variable not initialized for the input1 input2 and input3 - I cant initialize them because I need the program to return a error in case this variables is not defined and I cant put then on null to be able to find this error.

How to proceed?

public void print() {
    boolean input1;
    boolean input2;
    boolean input3;
    String gate;
    boolean calc;

    for (String a : operations.keySet()) {
        if (Gate2.contains(operations.get(a).Gate)) {
            if (inputs.containsKey(operations.get(a).input1)) {
                input1 = inputs.get(operations.get(a).input1);
            }
            if (inputs.containsKey(operations.get(a).input2)) {
                input2 = inputs.get(operations.get(a).input2);
            }
            if (result.containsKey(operations.get(a).input1)) {
                input1 = result.get(operations.get(a).input1);
            }
            if (result.containsKey(operations.get(a).input2)) {
                input2 = result.get(operations.get(a).input2);
            }
            gate = operations.get(a).Gate;
            calc = cc.calc(input1, input2, gate);
            result.put(a, calc);

        }else if (Gate3.contains(operations.get(a).Gate)) {
            if (inputs.containsKey(operations.get(a).input1)) {
                input1 = inputs.get(operations.get(a).input1);
            }
            if (inputs.containsKey(operations.get(a).input2)) {
                input2 = inputs.get(operations.get(a).input2);
            }
            if (inputs.containsKey(operations.get(a).input3)) {
                input3 = inputs.get(operations.get(a).input3);
            }
            if (result.containsKey(operations.get(a).input1)) {
                input1 = result.get(operations.get(a).input1);
            }
            if (result.containsKey(operations.get(a).input2)) {
                input2 = result.get(operations.get(a).input2);
            }
            if (result.containsKey(operations.get(a).input3)) {
                input3 = result.get(operations.get(a).input3);
            }
            gate = operations.get(a).Gate;
            calc = cc.calc(input1,input2,input3, gate);
            result.put(a, calc);

        }else if ("not".equals(operations.get(a).Gate)) {
            if (inputs.containsKey(operations.get(a).input1)) {
                input1 = inputs.get(operations.get(a).input1);
            }

            if (result.containsKey(operations.get(a).input1)) {
                input1 = result.get(operations.get(a).input1);
            }

            gate = operations.get(a).Gate;
            calc = cc.calc(input1, gate);
            result.put(a, calc);
        }

    }

    System.out.format(" Inputs --> ");
    for (String a : inputs.keySet()) {

        int bit2 = inputs.get(a) ? 1 : 0;
        System.out.format("%5s", bit2);
    }
    System.out.format(" Results --> ");
    for (String a : result.keySet()) {

        int bit2 = result.get(a) ? 1 : 0;
        System.out.format("%3s", bit2);
    }
    System.out.format("\n");

}

Answer 1

you are using primitive boolean, so you need to initialize it to either true or false. You can use wrapper java.lang.Boolean instead.

Answer 2

To expand on that, Boolean is effectively tri-state: true, false or null. So you can put

Boolean input1 = null;
...
if (input1 == null) ...

Answer 3

对于局部变量，我们需要在使用之前对其进行初始化，而对于类/实例变量，则将它们隐式初始化为默认值（对于对象，则为null）

Answer 4

使用可以具有true / false / null的布尔类，或使用另一个变量来指示它们是否已初始化：您可以将它们初始化为false，添加另一个变量isInit并将其也初始化为false，一旦初始化变量，则切换isInit为真，这样您就可以检查它们是否使用isInit进行了初始化