Java 百分比计算未处理，我不明白为什么

Question

下面是一段代码:

System.out.println("Calc: " + totalMs[0] + " divided by " + totalTestMs + " times 100");
System.out.println("Calc 2: " + totalBits[0] + " divided by " + totalCount[0] + " divided by 1000000");

DecimalFormat df = new DecimalFormat("0.00");

String b1 = "0", b2 = "0", b3 = "0", b4 = "0", b5 = "0", b6 = "0", b7 = "0", b8 = "0", b9 = "0", b10 = "0";
String b1Pct = "0";

if (totalCount[0] > 0) { 
    b1Pct = df.format((totalMs[0]/totalTestMs)*100);
    b1 = df.format((totalBits[0]/totalCount[0])/1000000); 
}

Calc 失败，Calc 2 通过。上述系统打印显示的输出是:

如您所见，这些数字似乎正确地通过了。但是，当我的系统输出 b1Pct 结果时，它显示为“0.0”。在这种情况下，它应该是 22.73。

我确定这很简单，但我无法弄明白。更令人困惑的是第二个是正确的!

Answer 1

看起来您正在为 Calc 做整数除法。当你将两个整数相除时，你得到一个整数，余数被丢弃，即:

System.out.println("Integer divide: " + 40/100); //Result is 0

您需要将其中一个转换为 float ，只需添加一个小数，即:

System.out.println("Decimal divide: " +  40/100.); //Result is .40
System.out.println("Cast divide: " + 40/((float)100)); //Result is .40

干杯!