使用 printf 和 format 进行格式化

2022-01-12 00:00:00 formatting java scjp ocpjp

在下面的程序中

class ZiggyTest2 {

    public static void main(String[] args){     

        double x = 123.456;
        char c = 65;
        int i = 65;

        System.out.printf("%s",x);
        System.out.printf("%b",x);
        System.out.printf("%c",c);
        System.out.printf("%5.0f",x);
        System.out.printf("%d",i);
    }       
}

输出是

123.456trueA  12365

谁能解释一下双精度值(即123.456)如何转换为布尔值(即true)

Can someone please explain how a double value (i.e. 123.456) is converted to a boolean (ie. true)

我问的原因是因为我知道 java 不允许将数字用于布尔值.例如，Java 中不允许以下内容

The reason I ask is because I know java does not allow numbers to be used for boolean values. For example, the following is not allowed in Java

if (5) { //do something }

谢谢

推荐答案

for "%b" : 如果参数 arg 为 null，则结果为 "false".如果 arg 是布尔值或布尔值，则结果是 String.valueOf() 返回的字符串.否则，结果为真".

for "%b" : If the argument arg is null, then the result is "false". If arg is a boolean or Boolean, then the result is the string returned by String.valueOf(). Otherwise, the result is "true".

参考

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