關閉的應用程序

Question

所以我想實現一個ProgressBar並將其設置爲100％，但不知何故它會在模擬器中崩潰。

繼承人的代碼（MainActivity.java）：

package com.example.schwarzerritter.remotec; 

import android.content.Intent; 
import android.support.v7.app.AppCompatActivity; 
import android.os.Bundle; 
import android.view.View; 
import android.widget.Button; 
import android.widget.ProgressBar; 

public class MainScreen extends AppCompatActivity { 

    ProgressBar fuelBar; 




    public Button lDoor; 

    public void lDoorPageOpen() { 
     lDoor = (Button) findViewById(R.id.lDoor);//weist unseren Button lDoor in Java zu 
     lDoor.setOnClickListener(new View.OnClickListener() {// 
      @Override 
      public void onClick(View v) { 
       Intent lDoorPage = new Intent(MainScreen.this, lDoorPageOpen.class);//deklarieren eines intents 
       startActivity(lDoorPage);//starte intent lDoorPage 
      } 
     }); 
    } 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main_screen); 
     fuelBar.setProgress(100); 
     lDoorPageOpen(); 
     fuelBar =(ProgressBar)findViewById(R.id.fuelB); 

    } 
} 

，這是.xml文件：

<?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.example.schwarzerritter.remotec.MainScreen" 
    tools:layout_editor_absoluteY="81dp" 
    tools:layout_editor_absoluteX="0dp"> 

    <TextView 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:text="RemoteC" 
     android:id="@+id/remoteC" 
     tools:layout_constraintTop_creator="1" 
     tools:layout_constraintRight_creator="1" 
     app:layout_constraintRight_toRightOf="parent" 
     android:layout_marginTop="16dp" 
     tools:layout_constraintLeft_creator="1" 
     app:layout_constraintLeft_toLeftOf="parent" 
     app:layout_constraintTop_toTopOf="parent" /> 

    <Button 
     android:id="@+id/lDoor" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:fontFamily="monospace" 
     android:text="LOCK" 
     tools:layout_constraintTop_creator="1" 
     tools:layout_constraintRight_creator="1" 
     app:layout_constraintRight_toRightOf="@+id/remoteC" 
     android:layout_marginTop="103dp" 
     tools:layout_constraintLeft_creator="1" 
     app:layout_constraintLeft_toLeftOf="@+id/acB" 
     app:layout_constraintTop_toTopOf="parent" /> 

    <Button 
     android:id="@+id/fuelB" 
     android:layout_width="94dp" 
     android:layout_height="50dp" 
     android:fontFamily="monospace" 
     android:text="FUEL" 
     tools:layout_constraintTop_creator="1" 
     tools:layout_constraintRight_creator="1" 
     tools:layout_constraintBottom_creator="1" 
     app:layout_constraintBottom_toBottomOf="@+id/locB" 
     android:layout_marginEnd="41dp" 
     app:layout_constraintRight_toRightOf="@+id/locB" 
     android:layout_marginTop="70dp" 
     app:layout_constraintTop_toBottomOf="@+id/remoteC" 
     android:layout_marginBottom="65dp" 
     android:layout_marginRight="41dp" /> 

    <Button 
     android:id="@+id/acB" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:fontFamily="monospace" 
     android:text="AC" 
     tools:layout_constraintTop_creator="1" 
     android:layout_marginStart="48dp" 
     android:layout_marginTop="19dp" 
     app:layout_constraintTop_toBottomOf="@+id/lDoor" 
     tools:layout_constraintLeft_creator="1" 
     app:layout_constraintLeft_toLeftOf="parent" 
     android:layout_marginLeft="48dp" /> 

    <Button 
     android:id="@+id/locB" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:fontFamily="monospace" 
     android:text="LOCATION" 
     app:layout_constraintBottom_toBottomOf="@+id/fuelB" 
     app:layout_constraintTop_toTopOf="@+id/acB" 
     app:layout_constraintVertical_bias="0.0" 
     tools:layout_constraintBottom_creator="1" 
     tools:layout_constraintTop_creator="1" 
     app:layout_constraintRight_toRightOf="parent" 
     app:layout_constraintLeft_toLeftOf="parent" 
     app:layout_constraintHorizontal_bias="0.859" /> 

    <Button 
     android:id="@+id/engB" 
     android:layout_width="0dp" 
     android:layout_height="49dp" 
     android:fontFamily="monospace" 
     android:text="ENGINE START" 
     tools:layout_constraintTop_creator="1" 
     tools:layout_constraintRight_creator="1" 
     android:layout_marginStart="8dp" 
     android:layout_marginEnd="8dp" 
     app:layout_constraintRight_toRightOf="parent" 
     android:layout_marginTop="35dp" 
     app:layout_constraintTop_toBottomOf="@+id/locB" 
     tools:layout_constraintLeft_creator="1" 
     app:layout_constraintLeft_toLeftOf="parent" 
     android:layout_marginLeft="8dp" 
     android:layout_marginRight="8dp" /> 

    <ProgressBar 
     android:id="@+id/fuelB" 
     style="?android:attr/progressBarStyleHorizontal" 
     android:layout_width="370dp" 
     android:layout_height="42dp" 
     tools:layout_editor_absoluteX="8dp" 
     tools:layout_editor_absoluteY="310dp" /> 



</android.support.constraint.ConstraintLayout> 

Answer 1

首先初始化進度然後使用setProgress（100）。

fuelBar =(ProgressBar)findViewById(R.id.fuelB); 
lDoorPageOpen(); 
fuelBar.setProgress(100); 

Answer 2

檢查您的代碼的順序，進度條必須在設置進度前進行初始化。