[英]Summing elements in an Array List after adding a new element in net beans
在net bean中添加一個新元素后立即對數組列表中的元素求和會導致添加的第一個元素不計入總和。然后當我添加另一個元素時,它只會對添加的第二個元素求和。代碼在下面並且有一個圖像我的問題。
https://gyazo.com/12f13ab5724af3de8d9848994987910d
private void balanceAddActionPerformed(java.awt.event.ActionEvent evt) {
try {
outputBox.setText("");
String check = addInput.getText();
int check1 = check.length();
if ("".equals(check)) {
errorLabel.setText("Nothing has been entered to be added.");
for (int i = 0; i < balance.size(); i++) {
outputBox.setText(outputBox.getText() + balance.get(i) + "\n");
}
} else if (check1 >= 7) {
errorLabel.setText("Too many characters limit your characters to 7");
addInput.setText("");
for (int i = 0; i < balance.size(); i++) {
outputBox.setText(outputBox.getText() + balance.get(i) + "\n");
}
} else {
double list = Integer.parseInt(addInput.getText());
balance.add(list);
addInput.setText("");
//Setting the array list in outputbox
for (double i = 0; i < balance.size(); i++) {
outputBox.setText(outputBox.getText() + balance.get((int) i) + "\n");
errorLabel.setText("");
double sum = 0;
for (double j = 1; j < balance.size(); j++) {
sum += balance.get((int) j);
String converted = String.valueOf(sum);
errorLabel.setText("Your sum is " + (converted));
}
}
}
} catch (Exception e) {
errorLabel.setText("Error wrong characters.");
for (int i = 0; i < balance.size(); i++) {
outputBox.setText(outputBox.getText() + balance.get(i) + "\n");
}
}
}
主要問題是您要從1
開始求和循環,這就是跳過第一個索引0
的原因:
for(int j=0; j<balance.size(); j++){
sum += balance.get(j);
}
String converted = String.valueOf(sum);
errorLabel.setText("Your sum is " + (converted) );
其他旁注:
j
聲明為double
(然后將其強制轉換為int
) 為了使整個過程更整潔,您可以使用for-each
循環,因為您不需要索引(並且因為ArrayList
是可迭代的)
for(double b: balance){ sum += b; }
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