为什么我不能使用三元？运算符在两个函数调用之间进行选择 [英] Why can't I use the ternary ? operator to select between two function calls?

问题描述

我最近编程并遇到了一个问题？ ：操作数。这是我的代码。

I was recently programming and ran into an issue using the ? : operand. Here's my code.

    Random rand = new Random();
    for(int x = 0; x < 3; x++) {
        rand.nextInt(1) == 0 ? vertShip(board) : horizShip(board);
    }

我的编译器抛出一个错误，指出该行的左侧（ rand.nextInt（1）== 0）必须是变量。我尝试过变种，例如

My compiler throws me an error stating that the left hand side of the line (rand.nextInt(1) == 0 ) must be a variable. I've tried variants such as

    Random rand = new Random();
    int a = rand.nextInt(1);
    for(int x = 0; x < 3; x++) {
        a == 0 ? vertShip(board) : horizShip(board);
    }

或左侧的陈述但是它们无法解决问题。有人能帮助我吗？

or if statements in the left hand side but they don't fix the problem. Would anyone be able to help me?

推荐答案

并非每个表达都是一个陈述。在此处使用 if 语句。请参阅 14.8表达式声明部分在Java SE 7 Java语言规范中。

Not every expression is a statement. Use an if statement here. See Section 14.8 Expression Statements in the Java SE 7 Java Language Specification.

某些类型的表达式可以作为语句使用分号后跟
。

Certain kinds of expressions may be used as statements by following them with semicolons.

ExpressionStatement:
    StatementExpression ;

StatementExpression:
    Assignment
    PreIncrementExpression
    PreDecrementExpression
    PostIncrementExpression
    PostDecrementExpression
    MethodInvocation
    ClassInstanceCreationExpression

以上各项的表达式语句示例：

Examples of expression statement for each of the above:

x = y;
++x;
--x
x++;
x--;
fn(); // Or donkey.fn();, etc.
new Donkey(this);

你不能做的是：

b ? f() : g();
f() + g();

但是，如果您对代码进行模糊处理，我想您可以写：

However, if you're dead set on obfuscating your code, I guess you could write:

fn(a == 0 ? vertShip(board) : horizShip(board));
(a == 0 ? vertShip(board) : horizShip(board)).fn();

（我想。我没有编译器，也不会写这样的代码。）

(I think. I don't have a compiler to hand and wouldn't usually write such code.)

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