Predict the output · Java

Integer Cache and ==

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What does this print?

public class Main {
    public static void main(String[] args) {
        Integer a = 127, b = 127, c = 128, d = 128;
        System.out.println(a == b);
        System.out.println(c == d);
        System.out.println(c.equals(d));
    }
}

```
true
true
true
```
```
true
false
true
```
```
false
false
true
```
```
true
false
false
```

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Solution

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The output is:

true
false
true

Autoboxing uses Integer.valueOf, which caches values from −128 to 127. a and b are the same cached object, so == (reference comparison) is true; 128 creates two distinct objects, so c == d is false. equals compares values. Always compare boxed numbers with equals (or unbox).

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