“+"Java 类的运算符

2022-01-17 00:00:00 class numbers operator-overloading java

我有这样的课:

private static class Num {
    private int val;

    public Num(int val) {
        this.val = val;
    }
}

是否可以使用+"-操作符添加到类的对象?

Is it possible to add to objects of the class by using the "+"-operator?

Num a = new Num(18); Num b = new Num(26); Num c = a + b;

推荐答案

不，你不能.+ 仅对数字、字符和 String 进行重载，并且不允许定义任何额外的重载.

No, you can't. + is overloaded only for numbers, chars and String, and you are not allowed to define any additional overloadings.

有一种特殊情况，当您可以连接任何对象的字符串表示时 - 如果前两个操作数中有 String 对象，则调用 toString()在所有其他对象上.

There is one special case, when you can concatenate any objects' string representation - if there is a String object in the first two operands, toString() is called on all other objects.

这是一个插图:

int i = 0; String s = "s"; Object o = new Object(); Foo foo = new Foo(); int r = i + i; // allowed char c = 'c' + 'c'; // allowed String s2 = s + s; // allowed Object o2 = o + o; // NOT allowed Foo foo = foo + foo; // NOT allowed String s3 = s + o; // allowed, invokes o.toString() and uses StringBuilder String s4 = s + o + foo; // allowed String s5 = o + foo; // NOT allowed - there's no string operand

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