在Java中，如何将两个数字之间的所有整数相加？

Question

所以我在安卓 studio中制作了一个简单的sum应用程序

public void add(View view){
    EditText editText1 = (EditText) findViewById(R.id.editText);
    EditText editText2 = (EditText) findViewById(R.id.editText2);
    EditText editText3 = (EditText) findViewById(R.id.editText3);

    Float firstNumber = Float.valueOf(editText1.getText().toString());
    Float secondNumber = Float.valueOf(editText2.getText().toString());

    Float sum = firstNumber + secondNumber;

    editText3.setText(sum.toString());
}

为了求两个数之间的所有整数之和，我应该如何更改此值 例如，如果Text1=1和Text2=5，则总和应为1+2+3+4+5

Answer 1

试试这个

    int firstNumber, secondNumber;
    float ans = 0;  
    Button.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
         ans = 0;
        firstNumber = Integer.parseInt(editText1.getText().toString());
        secondNumber = Integer.parseInt(editText2.getText().toString());

        for (; firstNumber <= secondNumber; firstNumber++) {
            ans += firstNumber;
        }
        editText3.setText(ans + "");
    }
});

Answer 2

比如：

public void add(View view){
    EditText editText1 = (EditText) findViewById(R.id.editText);
    EditText editText2 = (EditText) findViewById(R.id.editText2);
    EditText editText3 = (EditText) findViewById(R.id.editText3);

    int firstNumber = Integer.valueOf(editText1.getText().toString());
    int secondNumber = Integer.valueOf(editText2.getText().toString());

    int sum = 0;
    for(int i = firstNumber; i <= secondNumber; i++)
    {
        sum+=i;
    }

    editText3.setText("" + sum);
}

Answer 3

你可以用这个方法来求和

int sum(int smallest, int largest) {
    int length = (largest - smallest + 1);

    int sum = length * (smallest + largest) / 2;

    return sum;
}

你可以这样打电话

int firstNumber = Integer.parseInt(editText1.getText().toString());
int secondNumber = Integer.parseInt(editText2.getText().toString());

int sum = sum(firstNumber, secondNumber);

editText3.setText(sum.toString());