Shuhart stepview 空对象引用

Question

我将shuhart's stepview 用于我的Android 应用程序。我关注了这个video。但是每当我尝试输入我的 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) 

我不知道如何解决它。

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，找不到与此相关的问题。

请帮忙，提前谢谢

Answer 1

我设法通过编辑我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);