代码似乎没问题。但是，当我在模拟器中运行它时，应用程序无法正常工作。
代码：
package com.example.claudia.myapplication;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
public class MainActivity extends ActionBarActivity {
@Override// Calculating Body mass index
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final Button button_Calc = (Button) findViewById(R.id.button_Calc);
final EditText Field_Weight = (EditText) findViewById(R.id.Field_Weight);
final EditText Field_Height = (EditText) findViewById(R.id.Field_Height);
final TextView View_Result = (TextView) findViewById(R.id.View_Results);
final TextView View_Msg = (TextView) findViewById(R.id.View_Msg);
button_Calc.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
double weight;
double height;
double bmi;
String msg = "";
if (Field_Height.getText().toString().equals("") || Field_Weight.getText().toString().equals("")) {
Toast.makeText(getApplicationContext(), "No Valid Values!", Toast.LENGTH_LONG).show();
weight = Double.parseDouble(Field_Weight.getText().toString());
height = Double.parseDouble(Field_Height.getText().toString());
bmi = height * height;
bmi = weight / bmi;
View_Result.setText(String.valueOf(bmi));
if (bmi < 18.5) {
msg = "Client is Under Weight :(";
} else if (bmi > 18.5 && bmi < 25) {
msg = "Normal :)";
} else if (bmi > 25) {
msg = "Client is Overweight";
}
View_Msg.setText(msg);
}
}
});
// Calculating Calories in and out
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final Button Cal_calc = (Button) findViewById(R.id.Cal_calc);
final EditText field_cal = (EditText) findViewById(R.id.field_Cal);
final EditText field_burn = (EditText) findViewById(R.id.field_burn);
final TextView View_calRes = (TextView) findViewById(R.id.View_calRes);
final TextView View_calMsg = (TextView) findViewById(R.id.view_calMsg);
Cal_calc.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
double calories;
double burn;
double CaloricTotal;
String calMsg = "";
if (field_cal.getText().toString().equals("") || field_burn.getText().toString().equals("")) {
Toast.makeText(getApplicationContext(), "No Valid Values!", Toast.LENGTH_LONG).show();
calories = Double.parseDouble(field_cal.getText().toString());
burn = Double.parseDouble(field_burn.getText().toString());
CaloricTotal = calories * calories;
CaloricTotal = burn / CaloricTotal;
View_calRes.setText(String.valueOf(CaloricTotal));
if (CaloricTotal < 1500) {
calMsg = "Client Needs to consume more Calories :(";
} else if (CaloricTotal > 1500 && CaloricTotal < 2000) {
calMsg = "Client is Normal :)";
} else if (CaloricTotal > 2000) {
calMsg = "Client Needs to consume less calories";
}
View_calMsg.setText(calMsg);
}
}
});
}
}}
RUN错误::
11/01 22:57:40: Launching app
$ adb shell am start -n "com.example.claudia.myapplication/com.example.claudia.myapplication.MainActivity" -a android.intent.action.MAIN -c android.intent.category.LAUNCHER
Connected to process 3591 on device emulator-5554
I/art: Not late-enabling -Xcheck:jni (already on)
W/art: Unexpected CPU variant for X86 using defaults: x86
W/System: ClassLoader referenced unknown path: /data/app/com.example.claudia.myapplication-2/lib/x86
I/InstantRun: Instant Run Runtime started. Android package is com.example.claudia.myapplication, real application class is null.
[ 11-01 22:53:09.592 1515: 1538 D/ ]
HostConnection::get() New Host Connection established 0x95618500, tid 1538
W/System: ClassLoader referenced unknown path: /data/app/com.example.claudia.myapplication-2/lib/x86
W/art: Before Android 4.1, method android.graphics.PorterDuffColorFilter android.support.graphics.drawable.VectorDrawableCompat.updateTintFilter(android.graphics.PorterDuffColorFilter, android.content.res.ColorStateList, android.graphics.PorterDuff$Mode) would have incorrectly overridden the package-private method in android.graphics.drawable.Drawable
D/AndroidRuntime: Shutting down VM
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.claudia.myapplication, PID: 3591
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.claudia.myapplication/com.example.claudia.myapplication.MainActivity}: java.lang.IllegalStateException: Already attached
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2646)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)
Caused by: java.lang.IllegalStateException: Already attached
at android.support.v4.app.FragmentManagerImpl.attachController(FragmentManager.java:2132)
at android.support.v4.app.FragmentController.attachHost(FragmentController.java:104)
at android.support.v4.app.FragmentActivity.onCreate(FragmentActivity.java:315)
at android.support.v7.app.AppCompatActivity.onCreate(AppCompatActivity.java:85)
at com.example.claudia.myapplication.MainActivity.onCreate(MainActivity.java:63)
at android.app.Activity.performCreate(Activity.java:6664)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2599)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)
申请已终止。
答案 0 :(得分：0)
super.onCreate()和setContentView被调用两次。此外，还有不必要的括号。
答案 1 :(得分：0)
正如其他答案所述，由于多个原因导致Exception被抛出：
super.onCreate()被叫两次setContentView()被叫两次FIX ：
试试这段代码：
import android.support.v7.app.ActionBarActivity;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
public class MainActivity extends ActionBarActivity {
@Override// Calculating Body mass index
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final Button button_Calc = (Button) findViewById(R.id.button_Calc);
final EditText Field_Weight = (EditText)findViewById(R.id.Field_Weight);
final EditText Field_Height = (EditText)findViewById(R.id.Field_Height);
final TextView View_Result = (TextView)findViewById(R.id.View_Results);
final TextView View_Msg = (TextView)findViewById(R.id.View_Msg);
final Button Cal_calc = (Button)findViewById(R.id.Cal_calc);
final EditText field_cal = (EditText)findViewById(R.id.field_Cal);
final EditText field_burn = (EditText)findViewById(R.id.field_burn);
final TextView View_calRes = (TextView)findViewById(R.id.View_calRes);
final TextView View_calMsg = (TextView)findViewById(R.id.view_calMsg);
button_Calc.setOnClickListener(new View.OnClickListener()
{
@Override
public void onClick(View v) {
double weight;
double height;
double bmi;
String msg = "";
if (Field_Height.getText().toString().equals("") || Field_Weight.getText().toString().equals("")) {
Toast.makeText(getApplicationContext(), "No Valid Values!", Toast.LENGTH_LONG).show();
weight = Double.parseDouble(Field_Weight.getText().toString());
height = Double.parseDouble(Field_Height.getText().toString());
bmi = height * height;
bmi = weight / bmi;
View_Result.setText(String.valueOf(bmi));
if (bmi < 18.5) {
msg = "Client is Under Weight :(";
} else if (bmi > 18.5 && bmi < 25) {
msg = "Normal :)";
} else if (bmi > 25) {
msg = "Client is Overweight";
}
View_Msg.setText(msg);
}
}
});
Cal_calc.setOnClickListener(new View.OnClickListener()
{
@Override
public void onClick(View v) {
double calories;
double burn;
double CaloricTotal;
String calMsg = "";
if (field_cal.getText().toString().equals("") || field_burn.getText().toString().equals("")) {
Toast.makeText(getApplicationContext(), "No Valid Values!", Toast.LENGTH_LONG).show();
calories = Double.parseDouble(field_cal.getText().toString());
burn = Double.parseDouble(field_burn.getText().toString());
CaloricTotal = calories * calories;
CaloricTotal = burn / CaloricTotal;
View_calRes.setText(String.valueOf(CaloricTotal));
if (CaloricTotal < 1500) {
calMsg = "Client Needs to consume more Calories :(";
} else if (CaloricTotal > 1500 && CaloricTotal < 2000) {
calMsg = "Client is Normal :)";
} else if (CaloricTotal > 2000) {
calMsg = "Client Needs to consume less calories";
}
View_calMsg.setText(calMsg);
}
}
});
}
}
注意：请检查是否缺少任何大括号，如果缺少任何大括号，请添加。