Shuhart步骤视图空对象引用

Question

我的android应用程序使用的是shuhart的stepview。我关注了这个视频。但每当我试图进入我的BookingActivity时，应用程序就会崩溃，并出现错误：

java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.estebeauty/com.example.estebeauty.activities.BookingActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void com.shuhart.stepview.StepView.setSteps(java.util.List)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3270)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3409)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2016)
at android.os.Handler.dispatchMessage(Handler.java:107)
at android.os.Looper.loop(Looper.java:214)
at android.app.ActivityThread.main(ActivityThread.java:7356)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void com.shuhart.stepview.StepView.setSteps(java.util.List)' on a null object reference
at com.example.estebeauty.activities.BookingActivity.setupStepView(BookingActivity.java:88)
at com.example.estebeauty.activities.BookingActivity.onCreate(BookingActivity.java:38)
at android.app.Activity.performCreate(Activity.java:7802)
at android.app.Activity.performCreate(Activity.java:7791)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1299)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3245)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3409) 
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83) 
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135) 
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2016) 
at android.os.Handler.dispatchMessage(Handler.java:107) 
at android.os.Looper.loop(Looper.java:214) 
at android.app.ActivityThread.main(ActivityThread.java:7356) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930) 

我不知道该怎么修。

这是我的预订活动：

public class BookingActivity extends AppCompatActivity {
@BindView(R.id.step_view)
StepView stepView;
@BindView(R.id.view_pager)
ViewPager viewPager;
@BindView(R.id.btn_previous_step)
Button btn_previous_step;
@BindView(R.id.btn_next_step)
Button btn_next_step;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_booking);
ButterKnife.bind(BookingActivity.this);
setupStepView();
setColorButton();
// View
viewPager.setAdapter(new MyViewPagerAdapter(getSupportFragmentManager(), 1));
viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
@Override
public void onPageScrolled(int i, float v, int i1) {
}
@Override
public void onPageSelected(int i) {
if (i == 0) {
btn_previous_step.setEnabled(false);
}
else {
btn_previous_step.setEnabled(true);
setColorButton();
}
}
@Override
public void onPageScrollStateChanged(int i) {
}
});
}
private void setColorButton() {
if (btn_next_step.isEnabled()) {
btn_next_step.setBackgroundResource(R.color.colorPrimary);
}
else {
btn_next_step.setBackgroundResource(android.R.color.darker_gray);
}
if (btn_previous_step.isEnabled()) {
btn_previous_step.setBackgroundResource(R.color.colorPrimary);
}
else {
btn_previous_step.setBackgroundResource(android.R.color.darker_gray);
}
}
private void setupStepView() { // It fails here
List<String> stepList = new ArrayList<>(); 
stepList.add("Treatment");
stepList.add("Date");
stepList.add("Employee");
stepList.add("Confirm");
stepView.setSteps(stepList);
}
}

我查看了GitHub，找不到任何与此相关的问题。

请帮忙，并提前感谢

Answer 1

我通过编辑声明绑定的方式来修复它。所以我把它改成：

stepView = findViewById(R.id.step_view);
viewPager = findViewById(R.id.view_pager);
btn_previous_step = findViewById(R.id.btn_previous_step);
btn_next_step = findViewById(R.id.btn_next_step);