Question

我正在开发一个有五个片段的测验应用程序，每个片段都有一个问题。碎片以两种方式移动。

当用户点击某个选项时，会立即显示下一个片段。
我有一个倒数计时器，如果用户没有点击任何选项，那么10秒后片段就会被移动到新片段。

我已经实现了点击功能。当用户点击选项应用程序将其带到下一个片段但如果在下一个片段中用户单击无选项，则应用程序立即停止。请仔细看看，我正在分享代码。

Question.java（Fragment1）

 package com.example.sheikhspc.testapp;


import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.drawable.ShapeDrawable;
import android.os.Bundle;
import android.os.CountDownTimer;
import android.app.Fragment;
import android.app.FragmentManager;
import android.app.FragmentTransaction;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.RelativeLayout;
import android.widget.TextView;


public class Question1 extends Fragment implements View.OnClickListener {


public Question1() {
    // Required empty public constructor
}
int counter = 0;
View view;
Fragment frag = null;
TextView tv;
ImageView imageView1, imageViewR, imageView2;

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    view = inflater.inflate(R.layout.fragment_question1, container, false);
    imageView1 = (ImageView) view.findViewById(R.id.wrong1);
    imageViewR = (ImageView) view.findViewById(R.id.right);
    imageView2 = (ImageView) view.findViewById(R.id.wrong2);
    tv = (TextView) view.findViewById(R.id.timer1);

    imageView1.setOnClickListener(this);
    imageViewR.setOnClickListener(this);
    imageView2.setOnClickListener(this);
    new CountDownTimer(10000, 1000) {

        public void onTick(long millisUntilFinished) {
            tv.setText("Remaining Time: " + millisUntilFinished / 1000);
            //here you can have your logic to set text to edittext
        }

        public void onFinish() {
            frag = new Question2();
            FragmentManager fmm = getFragmentManager();
            FragmentTransaction fragmentTransactionn =  fmm.beginTransaction();
            fragmentTransactionn.addToBackStack(null);

            fragmentTransactionn.replace(R.id.container, frag);

            fragmentTransactionn.commit();

        }


    }.start();


    return view;
}


@Override
public void onClick(View v) {
    switch (v.getId()) {
        case R.id.wrong1:
            frag = new Question2();
            FragmentManager fm = getFragmentManager();
            FragmentTransaction fragmentTransaction = fm.beginTransaction();

            fragmentTransaction.replace(R.id.container,frag);

            fragmentTransaction.commit();

            break;
        case R.id.right:
            frag = new Question2();
            FragmentManager fm1 = getFragmentManager();
            FragmentTransaction fragmentTransaction1 = fm1.beginTransaction();

            fragmentTransaction1.replace(R.id.container,frag);

            fragmentTransaction1.commit();





            break;
        case R.id.wrong2:
            frag = new Question2();
            FragmentManager fm2 = getFragmentManager();
            FragmentTransaction fragmentTransaction2 = fm2.beginTransaction();

            fragmentTransaction2.replace(R.id.container,frag);

            fragmentTransaction2.commit();

            break;
        default:
            new CountDownTimer(10000, 1000) {

                public void onTick(long millisUntilFinished) {
                    tv.setText("Remaining Time: " + millisUntilFinished / 1000);
                    //here you can have your logic to set text to edittext
                }

                public void onFinish() {
                    frag = new Question2();
                    FragmentManager fmm = getFragmentManager();
                    FragmentTransaction fragmentTransactionn = fmm.beginTransaction();
                    fragmentTransactionn.addToBackStack(null);

                    fragmentTransactionn.replace(R.id.container, frag);

                    fragmentTransactionn.commit();

                }


            }.start();
            break;

    }
}
}

Question2.java（Fragment2）

package com.example.sheikhspc.testapp;


import android.app.FragmentManager;
import android.app.FragmentTransaction;
import android.os.Bundle;
import android.app.Fragment;
import android.os.CountDownTimer;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;


public class Question2 extends Fragment implements View.OnClickListener {


public Question2() {
    // Required empty public constructor
}


Fragment frag = null;
TextView tv;
View view;
ImageView imageView1, imageViewR, imageView2;

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    view = inflater.inflate(R.layout.fragment_question2, container, false);

    tv = (TextView)view.findViewById(R.id.timer2);
    imageView1 = (ImageView) view.findViewById(R.id.wrong1);
    imageViewR = (ImageView) view.findViewById(R.id.right);
    imageView2 = (ImageView) view.findViewById(R.id.wrong2);
    imageView1.setOnClickListener(this);
    imageViewR.setOnClickListener(this);
    imageView2.setOnClickListener(this);
    new CountDownTimer(10000, 1000) {

        public void onTick(long millisUntilFinished) {
            tv.setText("seconds remaining: " + millisUntilFinished / 1000);
            //here you can have your logic to set text to edittext
        }

        public void onFinish() {
            tv.setText("done!");
            frag = new Question3();
            FragmentManager fm = getFragmentManager();
            FragmentTransaction fragmentTransaction = fm.beginTransaction();

            fragmentTransaction.replace(R.id.container,frag);

            fragmentTransaction.commit();

        }

    }.start();


    return view;
}


@Override
public void onClick(View v) {
    switch (v.getId()) {
        case R.id.wrong1:
            frag = new Question3();
            FragmentManager fm = getFragmentManager();
            FragmentTransaction fragmentTransaction = fm.beginTransaction();

            fragmentTransaction.replace(R.id.container,frag);

            fragmentTransaction.commit();

            break;
        case R.id.right:
            frag = new Question3();
            FragmentManager fm1 = getFragmentManager();
            FragmentTransaction fragmentTransaction1 = fm1.beginTransaction();

            fragmentTransaction1.replace(R.id.container,frag);

            fragmentTransaction1.commit();





            break;
        case R.id.wrong2:
            frag = new Question3();
            FragmentManager fm2 = getFragmentManager();
            FragmentTransaction fragmentTransaction2 = fm2.beginTransaction();

            fragmentTransaction2.replace(R.id.container,frag);

            fragmentTransaction2.commit();

            break;
        default:
            new CountDownTimer(10000, 1000) {

                public void onTick(long millisUntilFinished) {
                    tv.setText("seconds remaining: " + millisUntilFinished / 1000);
                    //here you can have your logic to set text to edittext
                }

                public void onFinish() {
                    tv.setText("done!");
                    frag = new Question3();
                    FragmentManager fm = getFragmentManager();
                    FragmentTransaction fragmentTransaction = fm.beginTransaction();

                    fragmentTransaction.replace(R.id.container,frag);

                    fragmentTransaction.commit();

                }

            }.start();

            break;

    }
}
}

错误记录

E/AndroidRuntime: FATAL EXCEPTION: main
              Process: com.example.sheikhspc.testapp, PID: 32330
              java.lang.NullPointerException: Attempt to invoke virtual  method 'android.app.FragmentTransaction  android.app.FragmentManager.beginTransaction()' on a null object reference
                  at com.example.sheikhspc.testapp.Question1$1.onFinish(Question1.java:58)
                  at android.os.CountDownTimer$1.handleMessage(CountDownTimer.java:127)
                  at android.os.Handler.dispatchMessage(Handler.java:102)
                  at android.os.Looper.loop(Looper.java:135)
                  at android.app.ActivityThread.main(ActivityThread.java:5343)
                  at java.lang.reflect.Method.invoke(Native Method)
                  at java.lang.reflect.Method.invoke(Method.java:372)
                  at  com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:905)
                  at  com.android.internal.os.ZygoteInit.main(ZygoteInit.java:700)
I/Process: Sending signal. PID: 32330 SIG: 9
Application terminated.

Second.java（显示所有片段的活动）

package com.example.sheikhspc.testapp;

import android.app.FragmentManager;
import android.app.FragmentTransaction;
import android.os.Bundle;
import android.app.Fragment;
import android.os.CountDownTimer;
import android.provider.DocumentsContract;
import android.support.v7.app.AppCompatActivity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import android.widget.Toast;

public class Second extends AppCompatActivity {

Fragment frag;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_second);

    FragmentManager fm = getFragmentManager();
    FragmentTransaction fragmentTransaction = fm.beginTransaction();

    frag = new Question1();
    fragmentTransaction.replace(R.id.container,frag);

    fragmentTransaction.commit();

}
}

Answer 1

在点击替换片段之前，您需要取消定时器。

在CountDownTimer方法中创建onCreate的新实例时，将其分配给变量，例如

CountDownTimer timer = new CountDownTimer(10000, 1000) {...};
timer.start();

然后在onClick方法中，即当用户点击任何选项时，停止计时器，例如

@Override
public void onClick(View v) {
switch (v.getId()) {
    case R.id.btnNext:

        // Add this line to avoid crash
        timer.cancel();

        frag = new FragmentQuestion2();
        FragmentManager fm = getFragmentManager();
        FragmentTransaction fragmentTransaction = fm.beginTransaction();

        fragmentTransaction.replace(R.id.container,frag);

        fragmentTransaction.commit();

        break;
}

应用程序在使用倒数计时器时停止

1 个答案: