Java 不幸的是，简单应用程序已停止
我是android开发新手，我正在制作一个简单的计算器应用程序。。。每当我在android emulator中运行代码时，它都会向我显示不幸的是，SimpleApp已经停止。。。。我正在使用Android Studio编写代码，请帮助我。。。 以下是我的代码 activity_main.xmlJava 不幸的是，简单应用程序已停止,java,xml,android-studio,Java,Xml,Android Studio,我是android开发新手，我正在制作一个简单的计算器应用程序。。。每当我在android emulator中运行代码时，它都会向我显示不幸的是，SimpleApp已经停止。。。。我正在使用Android Studio编写代码，请帮助我。。。 以下是我的代码 activity_main.xml <?xml version="1.0" encoding="utf-8"?> <android.support.constraint.ConstraintLayout xmlns:and
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.myapp.simpleapp.MainActivity">
<TextView
android:id="@+id/textView"
android:layout_width="337dp"
android:layout_height="58dp"
android:contextClickable="false"
android:cursorVisible="false"
android:fontFamily="serif"
android:longClickable="true"
android:text="Calculator"
android:textAlignment="center"
android:textAllCaps="true"
android:textColor="@android:color/holo_red_dark"
android:textSize="36sp"
android:visibility="visible"
tools:layout_editor_absoluteX="24dp"
tools:layout_editor_absoluteY="31dp" />
<TextView
android:id="@+id/textView1"
android:layout_width="194dp"
android:layout_height="43dp"
android:text="Number 1: "
android:textColor="@android:color/black"
android:textSize="25sp"
tools:layout_editor_absoluteX="24dp"
tools:layout_editor_absoluteY="140dp" />
<TextView
android:id="@+id/textView2"
android:layout_width="194dp"
android:layout_height="44dp"
android:text="Number 2: "
android:textColor="@android:color/black"
android:textSize="25sp"
tools:layout_editor_absoluteX="24dp"
tools:layout_editor_absoluteY="217dp" />
<EditText
android:id="@+id/number2"
android:layout_width="99dp"
android:layout_height="43dp"
android:ems="10"
android:hint="Number 2"
android:inputType="number|numberSigned|numberDecimal"
android:singleLine="true"
android:textAlignment="center"
android:textColor="@android:color/black"
android:textIsSelectable="true"
android:textSize="20sp"
tools:layout_editor_absoluteX="262dp"
tools:layout_editor_absoluteY="217dp" />
<EditText
android:id="@+id/number1"
android:layout_width="99dp"
android:layout_height="43dp"
android:ems="10"
android:hint="Number 1"
android:inputType="number|numberSigned|numberDecimal"
android:linksClickable="false"
android:longClickable="true"
android:textAlignment="center"
android:textColor="@android:color/black"
android:textSize="20sp"
tools:layout_editor_absoluteX="262dp"
tools:layout_editor_absoluteY="140dp" />
<TextView
android:id="@+id/result"
android:layout_width="175dp"
android:layout_height="40dp"
tools:layout_editor_absoluteX="176dp"
tools:layout_editor_absoluteY="430dp" />
<TextView
android:id="@+id/textView5"
android:layout_width="103dp"
android:layout_height="40dp"
android:text="Result: "
android:textColor="@android:color/black"
android:textSize="25sp"
tools:layout_editor_absoluteX="59dp"
tools:layout_editor_absoluteY="433dp" />
<Button
android:id="@+id/btnAdd"
android:layout_width="152dp"
android:layout_height="49dp"
android:text="+"
android:textColor="@android:color/black"
android:textSize="30sp"
tools:layout_editor_absoluteX="24dp"
tools:layout_editor_absoluteY="292dp" />
<Button
android:id="@+id/btnSub"
android:layout_width="152dp"
android:layout_height="49dp"
android:text="-"
android:textColor="@android:color/black"
android:textIsSelectable="false"
android:textSize="30sp"
tools:layout_editor_absoluteX="216dp"
tools:layout_editor_absoluteY="292dp" />
<Button
android:id="@+id/btnDiv"
android:layout_width="152dp"
android:layout_height="49dp"
android:text="/"
android:textColor="@android:color/black"
android:textSize="25sp"
tools:layout_editor_absoluteX="24dp"
tools:layout_editor_absoluteY="362dp" />
<Button
android:id="@+id/btnMul"
android:layout_width="152dp"
android:layout_height="49dp"
android:text="*"
android:textAlignment="center"
android:textColor="@android:color/black"
android:textSize="25sp"
tools:layout_editor_absoluteX="216dp"
tools:layout_editor_absoluteY="362dp" />
</android.support.constraint.ConstraintLayout>
04-03 12:25:38.913 3927-3927/? E/memtrack: Couldn't load memtrack module (No such file or directory)
04-03 12:25:38.913 3927-3927/? E/android.os.Debug: failed to load memtrack module: -2
04-03 12:25:39.372 3952-3952/? E/memtrack: Couldn't load memtrack module (No such file or directory)
04-03 12:25:39.373 3952-3952/? E/android.os.Debug: failed to load memtrack module: -2
04-03 12:25:49.078 4097-4097/? E/memtrack: Couldn't load memtrack module (No such file or directory)
04-03 12:25:49.078 4097-4097/? E/android.os.Debug: failed to load memtrack module: -2
04-03 12:25:49.647 4122-4122/? E/memtrack: Couldn't load memtrack module (No such file or directory)
04-03 12:25:49.648 4122-4122/? E/android.os.Debug: failed to load memtrack module: -2
04-03 12:25:58.059 3666-3666/com.myapp.simpleapp E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.myapp.simpleapp, PID: 3666
java.lang.NumberFormatException: Invalid double: ""
at java.lang.StringToReal.invalidReal(StringToReal.java:63)
at java.lang.StringToReal.parseDouble(StringToReal.java:267)
at java.lang.Double.parseDouble(Double.java:301)
at com.myapp.simpleapp.MainActivity$4.onClick(MainActivity.java:70)
at android.view.View.performClick(View.java:4780)
at android.view.View$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)
04-03 12:25:58.079 1163-1163/? E/EGL_emulation: tid 1163: eglCreateSyncKHR(1299): error 0x3004 (EGL_BAD_ATTRIBUTE)
04-03 12:26:02.452 1810-2202/system_process E/InputDispatcher: channel '21dd8534 com.myapp.simpleapp/com.myapp.simpleapp.MainActivity (server)' ~ Channel is unrecoverably broken and will be disposed!
04-03 12:26:02.581 1175-1175/? E/audio_hw_generic: Error opening input stream format 1, channel_mask 0010, sample_rate 16000
在onCreate中使用findViewById，只有在EditText中输入值后才使用Double.parse 请尝试以下代码：
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final EditText number1 = (EditText) findViewById(R.id.number1);
final EditText number2 = (EditText) findViewById(R.id.number2);
Button add = (Button) findViewById(R.id.btnAdd);
Button sub = (Button) findViewById(R.id.btnSub);
Button div = (Button) findViewById(R.id.btnDiv);
Button mul = (Button) findViewById(R.id.btnMul);
final TextView txtresult = (TextView) findViewById(R.id.result);
add.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
double num1, num2, result;
num1 = Double.parseDouble(number1.getText().toString());
num2 = Double.parseDouble(number2.getText().toString());
result = num1 + num2;
txtresult.setText(Double.toString(result));
}
});
sub.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
double num1, num2, result;
num1 = Double.parseDouble(number1.getText().toString());
num2 = Double.parseDouble(number2.getText().toString());
result = num1 - num2;
txtresult.setText(Double.toString(result));
}
});
div.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
double num1, num2, result;
num1 = Double.parseDouble(number1.getText().toString());
num2 = Double.parseDouble(number2.getText().toString());
result = num1 / num2;
txtresult.setText(Double.toString(result));
}
});
mul.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
double num1, num2, result;
num1 = Double.parseDouble(number1.getText().toString());
num2 = Double.parseDouble(number2.getText().toString());
result = num1 * num2;
txtresult.setText(Double.toString(result));
}
});
}
}
此问题最常见的原因是运行时出现NullPointerException 要遵循的步骤： 观察Android Studio上的堆栈跟踪，如下所示：
然后，您可以分析堆栈跟踪，并关注到底是什么导致了异常，以及导致异常的行。或者，您可以发布堆栈跟踪的屏幕截图，以便更容易回答问题。不要对视图使用静态初始化。像所有的例子一样，我尝试过但结果相同。@Samrat请发布你的日志猫消息。@Samrat请为数字1和数字2插入一个整数值，然后单击+，-，etci没有，但什么都没有发生
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final EditText number1 = (EditText) findViewById(R.id.number1);
final EditText number2 = (EditText) findViewById(R.id.number2);
Button add = (Button) findViewById(R.id.btnAdd);
Button sub = (Button) findViewById(R.id.btnSub);
Button div = (Button) findViewById(R.id.btnDiv);
Button mul = (Button) findViewById(R.id.btnMul);
final TextView txtresult = (TextView) findViewById(R.id.result);
add.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
double num1, num2, result;
num1 = Double.parseDouble(number1.getText().toString());
num2 = Double.parseDouble(number2.getText().toString());
result = num1 + num2;
txtresult.setText(Double.toString(result));
}
});
sub.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
double num1, num2, result;
num1 = Double.parseDouble(number1.getText().toString());
num2 = Double.parseDouble(number2.getText().toString());
result = num1 - num2;
txtresult.setText(Double.toString(result));
}
});
div.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
double num1, num2, result;
num1 = Double.parseDouble(number1.getText().toString());
num2 = Double.parseDouble(number2.getText().toString());
result = num1 / num2;
txtresult.setText(Double.toString(result));
}
});
mul.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
double num1, num2, result;
num1 = Double.parseDouble(number1.getText().toString());
num2 = Double.parseDouble(number2.getText().toString());
result = num1 * num2;
txtresult.setText(Double.toString(result));
}
});
}
}