在给每个科目加上成绩后，我怎么能把它除以4呢?

Question

private void jButton4ActionPerformed(java.awt.event.ActionEvent evt) {                                         

double grades;
grades= Double.parseDouble(comprogGrds .getText())+Double.parseDouble (dsGrds .getText())+ Double.parseDouble (cwGrds.getText())+ Double.parseDouble(multGrds.getText())/4;

if(grades>=90){
average.setText(Double.toString(grades));
}else if(grades>=78 && grades<=79){
average.setText(Double.toString(grades));
}else if(grades>=74 && grades <=75){
average.setText(Double.toString(grades));
}

}

Answer 1

您刚刚错过了一组括号。你现在只把最后的数除以4。请尝试以下命令。

private void jButton4ActionPerformed(java.awt.event.ActionEvent evt) {                                         

double grades;
grades= (Double.parseDouble(comprogGrds .getText())+Double.parseDouble (dsGrds .getText())+ Double.parseDouble (cwGrds.getText())+ Double.parseDouble(multGrds.getText()))/4;

if(grades>=90){
average.setText(Double.toString(grades));
}else if(grades>=78 && grades<=79){
average.setText(Double.toString(grades));
}else if(grades>=74 && grades <=75){
average.setText(Double.toString(grades));
}

}

作为解释，如果你有double result = 3+6+9+2/4;，你将最终得到3+6+9+(2/4)。要解决这个问题，一组括号就足够了。double result = (3+6+9+2)/4;