android 当我调用 EditText 时应用程序崩溃

Question

调用 EDITTEXT 时应用程序崩溃。

布局

<EditText
    android:id="@+id/T_Price"
    android:layout_width="200dp"
    android:layout_height="wrap_content"
    android:layout_below="@+id/B_LessMoney"
    android:layout_centerHorizontal="true"
    android:layout_marginTop="65dp"
    android:text="@string/Price"
    android:visibility="visible" />

主要

    EditText mPrice = (EditText) findViewById(R.id.T_Price);

还有这份报告

E/AndroidRuntime: FATAL EXCEPTION: main Process: budgetreport.com.budgetreport, PID: 2791 java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{budgetreport.com.budgetreport/budgetreport.com.budgetreport.Report}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.Window$Callback android.view.Window.getCallback()' on a null object reference at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2488) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2665) at android.app.ActivityThread.-wrap11(ActivityThread.java) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1499) at android.os.Handler.dispatchMessage(Handler.java:111) at android.os.Looper.loop(Looper.java:207) at android.app.ActivityThread.main(ActivityThread.java:5765) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:789) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:679) Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.Window$Callback android.view.Window.getCallback()' on a null object reference at android.support.v7.app.AppCompatDelegateImplBase.(AppCompatDelegateImplBase.java:117) at android.support.v7.app.AppCompatDelegateImplV9.(AppCompatDelegateImplV9.java:149) at android.support.v7.app.AppCompatDelegateImplV11.(AppCompatDelegateImplV11.java:29) at android.support.v7.app.AppCompatDelegateImplV14.(AppCompatDelegateImplV14.java:54) at android.support.v7.app.AppCompatDelegateImplV23.(AppCompatDelegateImplV23.java:31) at android.support.v7.app.AppCompatDelegate.create(AppCompatDelegate.java:200) at android.support.v7.app.AppCompatDelegate.create(AppCompatDelegate.java:183) at android.support.v7.app.AppCompatActivity.getDelegate(AppCompatActivity.java:519) at android.support.v7.app.AppCompatActivity.findViewById(AppCompatActivity.java:190) at budgetreport.com.budgetreport.Report.(Report.java:21) at java.lang.Class.newInstance(Native Method) at android.app.Instrumentation.newActivity(Instrumentation.java:1072) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2478) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2665) at android.app.ActivityThread.-wrap11(ActivityThread.java) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1499) at android.os.Handler.dispatchMessage(Handler.java:111) at android.os.Looper.loop(Looper.java:207) at android.app.ActivityThread.main(ActivityThread.java:5765) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:789) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:679) I/Process: Sending signal. PID: 2791 SIG: 9 Application terminated.

Answer 1

您在 Activity 的 onCreate 方法之前调用 findViewById（在构造函数中？）。

你应该做的是在 Activity 的 onCreate 中初始化它：

Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.your_layout);
    mPrice = (EditText) findViewById(R.id.T_Price);
}

android 当我调用 EditText 时应用程序崩溃

android app crash when i call EditText

crash

android

android-layout