Java 我需要帮助错误E/AndroidRuntime:致命异常：主

我的项目有问题。。。。我是在一个试验项目中写的。现在，我把代码移到了主项目中。但是有一些问题。。我该怎么修

BmiMale.java

package com.example.liveprotect;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;
import androidx.appcompat.app.AppCompatActivity;

public class BmiMale extends AppCompatActivity {

    private EditText height;
    private EditText weight;
    private TextView result;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.bmi_male);
        getActionBar().setDisplayHomeAsUpEnabled(true);
        height = (EditText) findViewById(R.id.height);
        weight = (EditText) findViewById(R.id.weight);
        result = (TextView) findViewById(R.id.result);
    }

    public void mycalculateBMI(View v) {
        String heightStr = height.getText().toString();
        String weightStr = weight.getText().toString();

        if (heightStr != null && !"".equals(heightStr)
                && weightStr != null  &&  !"".equals(weightStr)) {
            float heightValue = Float.parseFloat(heightStr) / 100;
            float weightValue = Float.parseFloat(weightStr);

            float bmi = weightValue / (heightValue * heightValue);

            displayBMI(bmi);
        }
    }

    private void displayBMI(float bmi) {
        String bmiLabel = "";

        if (Float.compare(bmi, 15f) <= 0) {
            bmiLabel = getString(R.string.very_severely_underweight);
        } else if (Float.compare(bmi, 15f) > 0  &&  Float.compare(bmi, 16f) <= 0) {
            bmiLabel = getString(R.string.severely_underweight);
        } else if (Float.compare(bmi, 16f) > 0  &&  Float.compare(bmi, 18.5f) <= 0) {
            bmiLabel = getString(R.string.underweight);
        } else if (Float.compare(bmi, 18.5f) > 0  &&  Float.compare(bmi, 25f) <= 0) {
            bmiLabel = getString(R.string.normal);
        } else if (Float.compare(bmi, 25f) > 0  &&  Float.compare(bmi, 30f) <= 0) {
            bmiLabel = getString(R.string.overweight);
        } else if (Float.compare(bmi, 30f) > 0  &&  Float.compare(bmi, 35f) <= 0) {
            bmiLabel = getString(R.string.obese_class_i);
        } else if (Float.compare(bmi, 35f) > 0  &&  Float.compare(bmi, 40f) <= 0) {
            bmiLabel = getString(R.string.obese_class_ii);
        } else {
            bmiLabel = getString(R.string.obese_class_iii);
        }

        bmiLabel = bmi + "\n\n" + bmiLabel;
        result.setText(bmiLabel);
    }
}

当我单击按钮calculateBMI时

01-04 03:07:44.313 25665-25665/com.example.liveprotect E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.liveprotect, PID: 25665
    java.lang.IllegalStateException: Could not find method mycalculateBMI(View) in a parent or ancestor Context for android:onClick attribute defined on view class androidx.appcompat.widget.AppCompatButton with id 'calc'
        at androidx.appcompat.app.AppCompatViewInflater$DeclaredOnClickListener.resolveMethod(AppCompatViewInflater.java:436)
        at androidx.appcompat.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:393)
        at android.view.View.performClick(View.java:4780)
        at android.view.View$PerformClick.run(View.java:19866)
        at android.os.Handler.handleCallback(Handler.java:739)
        at android.os.Handler.dispatchMessage(Handler.java:95)
        at android.os.Looper.loop(Looper.java:135)
        at android.app.ActivityThread.main(ActivityThread.java:5254)
        at java.lang.reflect.Method.invoke(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:372)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)

---

不知道为什么你的方法不起作用。您可以采用另一种方法，在

onCreate

方法中显式设置按钮的onClick处理程序：

Button calcButton = (Button)findViewById(R.id.calc);
calcButton.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        mycalculateBMI(v);
    }
});

---

尝试清理/重建。关闭仿真器，然后再次尝试运行。我已经运行了，但仍然相同。它仍然存在相同的问题。我不明白为什么，当我将代码移动到MainActivity.java并更改

setContentView（R.layout.bmi_-male）时--->
setContentView（R.layout.activity\u main）
和
工具：context=“com.example.liveprotect.BmiMale
--->
工具：context=“.MainActivity”
我的应用程序正常工作。但每当我切换到“MainActivity”和“activity\u main”以外的其他应用程序时，我的应用程序就会再次出现问题。。。
01-04 03:07:44.313 25665-25665/com.example.liveprotect E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.liveprotect, PID: 25665
    java.lang.IllegalStateException: Could not find method mycalculateBMI(View) in a parent or ancestor Context for android:onClick attribute defined on view class androidx.appcompat.widget.AppCompatButton with id 'calc'
        at androidx.appcompat.app.AppCompatViewInflater$DeclaredOnClickListener.resolveMethod(AppCompatViewInflater.java:436)
        at androidx.appcompat.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:393)
        at android.view.View.performClick(View.java:4780)
        at android.view.View$PerformClick.run(View.java:19866)
        at android.os.Handler.handleCallback(Handler.java:739)
        at android.os.Handler.dispatchMessage(Handler.java:95)
        at android.os.Looper.loop(Looper.java:135)
        at android.app.ActivityThread.main(ActivityThread.java:5254)
        at java.lang.reflect.Method.invoke(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:372)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)

Button calcButton = (Button)findViewById(R.id.calc);
calcButton.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        mycalculateBMI(v);
    }
});