Java - 如何将字符串除以数字？

Question

新

BigDecimal i = BigDecimal.ZERO;
for (int row = 0; row < testMark.length; row++) {
    for (int col = 0; col < testMark[row].length; col++) {
        i.add(new BigDecimal(testMark[row][col]));
    }
}
i.divide(new BigDecimal(60D));
outPut.setText(i.toString());`

旧

查看代码底部。我想将整个 classAver 字符串除以 60，如 outPut.setText(classAver/60);

数组double[][] testMark = new double[15][4];

String classAver = "";
        for(int i=0; i < rowNumber; i++){
            classAver += ((testMark[0][0] + testMark[0][1] + testMark[0][2] + testMark[0][3])
                   +
                   (testMark[1][0] + testMark[1][1] + testMark[1][2] + testMark[1][3]) +
                   (testMark[2][0] + testMark[2][1] + testMark[2][2] + testMark[2][3]) +
                   (testMark[3][0] + testMark[3][1] + testMark[3][2] + testMark[3][3]) +
                   (testMark[4][0] + testMark[4][1] + testMark[4][2] + testMark[4][3]) +
                   (testMark[5][0] + testMark[5][1] + testMark[5][2] + testMark[5][3]) +
                   (testMark[6][0] + testMark[6][1] + testMark[6][2] + testMark[6][3]) +
                   (testMark[7][0] + testMark[7][1] + testMark[7][2] + testMark[7][3]) +
                   (testMark[8][0] + testMark[8][1] + testMark[8][2] + testMark[8][3]) +
                   (testMark[9][0] + testMark[9][1] + testMark[9][2] + testMark[9][3]) +
                   (testMark[10][0] + testMark[10][1] + testMark[10][2] + testMark[10][3]) +
                   (testMark[11][0] + testMark[11][1] + testMark[11][2] + testMark[11][3]) +
                   (testMark[12][0] + testMark[12][1] + testMark[12][2] + testMark[12][3]) +
                   (testMark[13][0] + testMark[13][1] + testMark[13][2] + testMark[13][3]) +
                   (testMark[14][0] + testMark[14][1] + testMark[14][2] + testMark[14][3]));
        }
outPut.setText(classAver); // <--How do I divide that number by 60? 

Answer 1

编辑

鉴于您指定的数组是 double[15][4]，您可以使用以下内容:

BigDecimal i = BigDecimal.ZERO;
for (int row = 0; row < testMark.length; row++) {
    for (int col = 0; col < testMark[row].length; col++) {
        i = i.add(new BigDecimal(testMark[row][col]));
    }
}
i = i.divide(new BigDecimal(60D));
outPut.setText(i.toString());

以后，如果您想要获得超过 60 个结果的平均值:

BigDecimal i = BigDecimal.ZERO;
int count = 0;
for (int row = 0; row < testMark.length; row++) {
    for (int col = 0; col < testMark[row].length; col++, count++) {
        i = i.add(new BigDecimal(testMark[row][col]));
    }
}
i = i.divide(new BigDecimal(count));
outPut.setText(i.toString());

旧答案

天哪，从哪里开始。

首先，循环:

for (int row = 0; row < 15; row++) { // these don't need to be concrete numbers ("15"), can be your array length
    for (int col = 0; col < 4; col++) {
        //append testMark[row][col]
    }
}

其次，使用StringBuilder，不要在循环中附加字符串

StringBuilder sb = new StringBuilder();
for (int row = 0; row < 15; row++) {
    for (int col = 0; col < 4; col++) {
        sb.append(testMark[row][col]); //can append delimiters, etc
    }
}
String value = sb.toString(); //Your complete value

然后，转换你的值(value):

BigInteger i = BigInteger.valueOf(classAver); //returns an int value
i = i.divide(new BigInteger(60));
outPut.setText(i.toString());

如果您不想将值添加为字符串，则可以将它们添加为数字:

BigInteger i = BigInteger.ZERO;
for (int row = 0; row < 15; row++) {
    for (int col = 0; col < 4; col++) {
        try {
            int raw = Integer.parseInt(testMark[row][col]);
            i = i.add(new BigInteger(raw));
        } catch (NumberFormatException ex) {
            System.err.println(String.format("Bad value caught! (Row: %d, Col: %d)", row, col));
        }
    }
}
i = i.divide(new BigInteger(60));
outPut.setText(i.toString());