Question

我的当前源代码存在问题。我对此很新。这是关于BMI计算，并将使用alertdialog显示输出。我已经把条件放了，但输出总是“你是超重”的其他条件，即使我的输入是合法的应该是IDEAL输出。

活动在跑步中没有出错，但我觉得这是我不知道的计算问题。如果这是一个重复的问题，我真的很抱歉。

public class BMIcalcu extends Activity{
    EditText weight, height;
    final Context context = this;
    Button calculate;
    float result, height1, weight1;

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

      height = (EditText)findViewById(R.id.editText1);
      weight = (EditText)findViewById(R.id.editText2);
      calculate = (Button)findViewbyId(R.id.btn_bmi);

      String str1 = height.getText().toString();
      String str2 = weight.getText().toString();

      try{
        height1 = Float.parseFloat(str1)/100;
        weight1 = Float.parseFloat(str2);
        }catch(NumberFormatException nfe){
          }

      calculate.setOnClickListener(new View.OnClickListener(){

                                   @Override
                                   public void onClick(View v){
        result = weight1 / (height1*height1);
        if(result<18.5){

          AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(context);

          alertDialogBuilder.setTitle("Your BMI");

          alertDialogBuilder
                    .setMessage("You are UNDERWEIGHT! START EATING!")
                    .setCancelable(false)
                    .setPositiveButton("List", new DialogInterface.OnClickLister(){
                                       public void onClick(DialogInterface dialog, int id){
            Intent intent = new Intent(BMIcalcu.this, list.class);
            startActivity(intent);
            }
          })
                    .setNegativeButton("Back", new DialogInterface.OnClickListener(){
                                       public void onClick(DialogInterface dialog, int id){

                      dialog.cancel();
                      }
        });
      AlertDialog alertDialog = alertDialogBuilder.create();
      alertDialog.show();

      }
else if(result<25){

          AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(context);

          alertDialogBuilder.setTitle("Your BMI");

          alertDialogBuilder
                    .setMessage("You are on your IDEAL!")
                    .setCancelable(false)
                    .setPositiveButton("List", new DialogInterface.OnClickLister(){
                                       public void onClick(DialogInterface dialog, int id){
            Intent intent = new Intent(BMIcalcu.this, list.class);
            startActivity(intent);
            }
          })
                    .setNegativeButton("Back", new DialogInterface.OnClickListener(){
                                       public void onClick(DialogInterface dialog, int id){

                      dialog.cancel();
                      }
        });
      AlertDialog alertDialog = alertDialogBuilder.create();
      alertDialog.show();
}
else{


          AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(context);

          alertDialogBuilder.setTitle("Your BMI");

          alertDialogBuilder
                    .setMessage("You are OVERWEIGHT! START EXERCISING!")
                    .setCancelable(false)
                    .setPositiveButton("List", new DialogInterface.OnClickLister(){
                                       public void onClick(DialogInterface dialog, int id){
            Intent intent = new Intent(BMIcalcu.this, list.class);
            startActivity(intent);
            }
          })
                    .setNegativeButton("Back", new DialogInterface.OnClickListener(){
                                       public void onClick(DialogInterface dialog, int id){

                      dialog.cancel();
                      }
        });
      AlertDialog alertDialog = alertDialogBuilder.create();
      alertDialog.show();
}
}
});
}
}

这是xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="match_parent">
<EditText
  android:layout_gravity="center"
  android:layout_width="266dp"
  android:layout_height="wrap_content"
  android:inputType="text|number"
  android:hint="Height (Centimeter)"
  android:ems="10"
  android:id="@+id/editText1" />

<EditText
  android:layout_gravity="center"
  android:layout_width="266dp"
  android:layout_height="wrap_content"
  android:inputType="text|number"
  android:hint="Weight (Kilogram)"
  android:ems="10"
  android:id="@+id/editText2"/>

<Button
  android:id="@+id/btn_bmi"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:layout_gravity="center"
  android:layout_below="@+id/editText2"
  android:text="Calculate"/>
</LinearLayout>

Answer 1

在onClick（）中移动高度和重量分配。

calculate.setOnClickListener(new View.OnClickListener(){

        @Override
        public void onClick(View v){
  String str1 = height.getText().toString();
  String str2 = weight.getText().toString();

  try{
    height1 = Float.parseFloat(str1)/100;
    weight1 = Float.parseFloat(str2);
    }catch(NumberFormatException nfe){
      }

            result = weight1 / (height1*height1);
            String msg = "";
            if(result<18.5){
                msg = "You are UNDERWEIGHT! START EATING!";
            }
            else if(result<25){
                msg = "You are on your IDEAL!";
            }
            else{
                msg = "You are UNDERWEIGHT! START EATING!";
            }

            AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(context);

            alertDialogBuilder.setTitle("Your BMI");

            alertDialogBuilder
                    .setMessage(msg)
                    .setCancelable(false)
                    .setPositiveButton("List", new DialogInterface.OnClickLister(){
                        public void onClick(DialogInterface dialog, int id){
                            Intent intent = new Intent(BMIcalcu.this, list.class);
                            startActivity(intent);
                        }
                    })
                    .setNegativeButton("Back", new DialogInterface.OnClickListener(){
                        public void onClick(DialogInterface dialog, int id){

                            dialog.cancel();
                        }
                    });
            AlertDialog alertDialog = alertDialogBuilder.create();
            alertDialog.show();
        }
    });

Answer 2

您目前正在weight内设置height和onCreate()的值。首次创建onCreate时会调用Activity。 onCreate仅在Activity生命周期中调用一次。有关活动的更多信息，请访问：https://developer.android.com/guide/components/activities.html。

要回答您的问题，除非您要设置默认值，否则不应在weight中设置height和onCreate的值。尝试将它们移到onClick方法中：

calculate.setOnClickListener(new View.OnClickListener(){

    @Override
    public void onClick(View v){
        String str1 = height.getText().toString();
        String str2 = weight.getText().toString();

        try {
            height1 = Float.parseFloat(str1)/100;
            weight1 = Float.parseFloat(str2);
            result = weight1 / (height1*height1);
        }
        catch(NumberFormatException nfe) {

        }
        // Continue Alert Dialog stuff down here...

你为什么遇到这个问题？

目前，您的Activity启动并且onCreate被调用。您正在创建对xml的引用，然后尝试设置weight和height的值。但是，当调用onCreate时，用户尚未在EditText weight height中输入任何内容。因此，在此之后，假设用户输入了值。这些值不会记录在任何地方。然后，当用户单击Button以查看其BMI时，您尝试计算结果。结果中没有任何内容，因此始终会调用else。这就是你继续看到你输出的原因。

BMI计算，使用alertdialog输出

2 个答案: