Question

我想将edittext百万像素的内容更改为宽度和高度文本框的产品，以制作百万像素计算器。

public void calculate()
{

    EditText tb_widthpx = (EditText) findViewById(R.id.txtbox_widthpx);
    EditText tb_heightpx = (EditText)findViewById(R.id.txtbox_heigthpx);
    EditText tb_megapixel = (EditText) findViewById(R.id.txtbox_megapixel);

    if (tb_widthpx.getText().toString() != "" && tb_heightpx.getText().toString() !="")
    {
        int produkt;
        int width = Integer.parseInt(tb_widthpx.getText().toString());
        int height = Integer.parseInt((tb_heightpx.getText().toString()));

        produkt = width * height;
        tb_megapixel.setText(String.valueOf(produkt));
    }

Answer 1

在Java中你必须使用.equals()，所以试试这个，

public void calculate()
{

    EditText tb_widthpx = (EditText) findViewById(R.id.txtbox_widthpx);
    EditText tb_heightpx = (EditText)findViewById(R.id.txtbox_heigthpx);
    EditText tb_megapixel = (EditText) findViewById(R.id.txtbox_megapixel);

    if (!tb_widthpx.getText().toString().equals("") && !tb_heightpx.getText().toString().equals(""))
    {
        int produkt;
        int width = Integer.parseInt(tb_widthpx.getText().toString());
        int height = Integer.parseInt((tb_heightpx.getText().toString()));

        produkt = width * height;
        tb_megapixel.setText(String.valueOf(produkt));
    }

参考：Why you use .equals()

Answer 2

您可以使用.equals()来比较字符串。像这样：

if (!tb_widthpx.getText().toString().equals("") && !tb_heightpx.getText().toString().equals("")) {
    int produkt;
    int width = Integer.parseInt(tb_widthpx.getText().toString());
    int height = Integer.parseInt((tb_heightpx.getText().toString()));

    produkt = width * height;
    tb_megapixel.setText(String.valueOf(produkt));
}

但为了获得更好的性能，您应该使用.length()。像这样：

if (!tb_widthpx.getText().toString().length() == 0 && !tb_heightpx.getText().toString().length() == 0) {
    int produkt;
    int width = Integer.parseInt(tb_widthpx.getText().toString());
    int height = Integer.parseInt((tb_heightpx.getText().toString()));

    produkt = width * height;
    tb_megapixel.setText(String.valueOf(produkt));
}

为什么我的编辑文本没有更改内容？

2 个答案: