java - Java 新手，对名称/变量引用有疑问

Question

我已经使用这个网站搜索特定错误两个学期了。我知道我要问的问题比我在该网站上搜索/阅读的大多数内容更广泛和基本，但这是我在类之外必须寻求信息的唯一地方。

现在我正在使用 Android Studio 开发一个简单的照片计算器手机应用程序。它有 3 个单选按钮，每个按钮都分配了一个特定值。我知道我引用每个按钮并尝试触发计算的方式有问题。

当前的一些错误:

    Cannot resolve method'getText()'
    Operator '<' cannot be applied to 'android.widget.editText','int'
    Operator "*" cannot be applied to 'double', 'andriod.widget.EditText'

下面是代码:

        package com.example.squirreloverlord.ccarringtonphonephotoprint;

    import android.icu.text.DecimalFormat;
    import android.support.v7.app.AppCompatActivity;
    import android.os.Bundle;
    import android.view.View;
    import android.widget.Button;
    import android.widget.EditText;
    import android.widget.RadioButton;
    import android.widget.TextView;
    import android.widget.Toast;

    public class MainActivity extends AppCompatActivity {
    double small = 19;
    double medium = 49;
    double large = 79;
    double Result;
    double inputUser;
    double Number;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

    getSupportActionBar().setDisplayShowHomeEnabled(true);
    getSupportActionBar().setLogo(R.mipmap.ic_launcher);
    getSupportActionBar().setDisplayUseLogoEnabled(true);

        final EditText inputUser = (EditText)     findViewById(R.id.editTextNumber);
        final RadioButton radioButton4x6 = (RadioButton)     findViewById(R.id.radioButton4x6);
        final RadioButton radioButton5x7 = (RadioButton) findViewById(R.id.radioButton5x7);
        final RadioButton radioButton8x10  = (RadioButton)findViewById(R.id.radioButton8x10);
        final TextView Result = (TextView) findViewById(R.id.textViewResult);
        Button Calculate = (Button) findViewById(R.id.buttonCalculate);

        Calculate.setOnClickListener(new View.OnClickListener()  {
            @Override
            public void onClick(View v)  {
                inputUser=Double.parseDouble(Number.getText( ).toString(  ));
                DecimalFormat tenth = new DecimalFormat("#.#");

                if(radioButton4x6.isChecked( ))   {
                    if (inputUser <50) {
                        Number = small * inputUser;
                        Result.setText(tenth.format(Result) + " is your total cost!");

                    } else {
                        Toast.makeText(MainActivity.this,"Please enter a value less than 50", Toast.LENGTH_LONG).show();

                    }
                }
                if (radioButton5x7.isChecked( ))  {
                    if (inputUser <50) {
                        Number = medium * inputUser;
                        Result.setText(tenth.format(Result) + " is your total cost!");
                    }  else  {
                        Toast.makeText(MainActivity.this,"Please enter a value less than 50", Toast.LENGTH_LONG).show();
                    }
                }
                if (radioButton8x10.isChecked()) {
                    if (inputUser <50) {
                        Number = large * inputUser;
                        Result.setText(tenth.format(Result) + " is your total cost!");

                    }  else {
                        Toast.makeText(MainActivity.this,"Please enter a value less than 50", Toast.LENGTH_LONG).show();
                    }
                }
            }
        });

    }
}

预先感谢您提供的任何帮助。

Answer 1

我认为你应该像这样更改变量:

double inputUser;

和

final EditText inputUser = (EditText) findViewById(R.id.editTextNumber);

inputUser 会对这段代码感到困惑

inputUser=Double.parseDouble(Number.getText( ).toString(  ));

如果我是你，我会这样改变:

final EditText editUser= (EditText) findViewById(R.id.editTextNumber);

editUser=Double.parseDouble(editUser.getText( ).toString(  ));

然后喜欢代码editUser <50它将获得值

希望有帮助。

根据你的 double 印，改变如下:

prints=Double.parseDouble(editUser.getText( ).toString(  ));

那么你可以这样使用:

if (prints<50)