为什么我不能写 ch=ch+1;而不是 ch++;尽管它们具有相同的含义 [英] Why can't I write ch=ch+1; instead of ch++; though they have same meaning

问题描述

package practicejava;

public class Query {

    public static void main(String[] args) {
        char ch = 66;
        System.out.println("character= " + ch);

        ch++;

        System.out.println("character = " + ch);

    }
}

技术上 ch++; 和 ch=ch+1; 是一样的，但是为什么我写 ch=ch+1; 而不是 ch++;?

Technically ch++; and ch=ch+1; are the same but why do I get an error when I write ch=ch+1; instead of ch++;?

推荐答案

你需要提供一个演员表才能做到这一点:

You need to provide a cast in order to do that :

ch = (char) (ch + 1);

这是因为表达式 ch + 1 被提升(upcast)为 int.为了让您将此表达式重新分配给 char，您需要显式 downcast 它.

This is because the expression ch + 1 is is promoted (upcast) to an int. In order for you to reassign this expression to a char you need to explicitly downcast it.

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