我想从一个活动中获取代码，包括xml和java，并使用它创建一个与活动设计和功能完全相同的片段。我已经多次查看了有关Fragments的文档（https://developer.android.com/guide/components/fragments.html），并观看了大量关于它的YouTube视频。我从我的activity.java文件中复制并粘贴代码并将其直接粘贴到我的fragment.java文件中，然后我对那里的代码进行了更改。但是，我相信我对碎片有一种误解。
为了更好地解决我遇到的错误，我一直在疯狂地获取NullPointerExceptions。
我原始活动的原始java文件与xml一样完美。
package com.example.me.inserttitlename;
import android.content.Context;
import android.content.Intent;
import android.graphics.Point;
import android.os.Bundle;
import android.os.CountDownTimer;
import android.support.annotation.NonNull;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.view.WindowManager;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.RelativeLayout;
import android.widget.TextView;
import android.widget.Toast;
import android.view.InflateException;
import java.util.Random;
import java.util.Timer;
import java.util.TimerTask;
/**
* A simple {@link Fragment} subclass.
*/
public class LevelOneFragment extends Fragment {
//creating variables
private ImageView img;
private ViewGroup viewer;
TextView textCount;
Button failButton;
Button beginButton;
TextView countDownBeginText;
private TextView countDownMain;
public int scoreCounter;
public LevelOneFragment() {
// Required empty public constructor
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
// Inflate the layout for this fragment
super.onActivityCreated(savedInstanceState);
//setCont(R.layout.fragment_level_one);
// return inflater.inflate(R.layout.fragment_level_one,container, false);
View view = inflater.inflate(R.layout.fragment_level_one, container, true);
//creating viewables and such
viewer = (ViewGroup) view.findViewById(R.id.view_level);
img = (ImageView) view.findViewById(R.id.imageView);
failButton = (Button) view.findViewById(R.id.failureButton);
countDownMain = (TextView) view.findViewById(R.id.countDownMain);
countDownBeginText = (TextView) view.findViewById(R.id.countDownBeginText);
beginButton = (Button) view.findViewById(R.id.beginButton);
if (view != null) {
ViewGroup parent = (ViewGroup) view.getParent();
if (parent != null) {
parent.removeView(view);
}
}
try {
view = inflater.inflate(R.layout.fragment_level_one, container, false);
} catch (InflateException e) {
}
RelativeLayout.LayoutParams layoutParams = new RelativeLayout.LayoutParams(150, 150);
img.setLayoutParams(layoutParams);
img.setOnTouchListener(new LevelOneFragment.ChoiceTouchListener());
//begin random movement
startRandomButton(img);
//setting up button for failure CORRECT TO TAKE YOU TO THE MAIN MENU
failButton.setOnClickListener(new View.OnClickListener(){
public void onClick(View v){
startActivity(new Intent(getActivity(), MainMenu.class));
}
});
//setting countdown text to 3
countDownBeginText.setText(":3");
//begin countdown from three
beginButton.setOnClickListener(new View.OnClickListener(){
public void onClick(View beginT) {
CountDownTimer countDownTimer = new CountDownTimer(3*1000, 3) {
@Override
public void onTick(long millisUntilFinished) {
countDownBeginText.setText(":" + millisUntilFinished/1000);
//add possible sound here every tick
}
@Override
public void onFinish() {
beginButton.setVisibility(View.INVISIBLE);
countDownBeginText.setVisibility(View.INVISIBLE);
//countdown from 60------- change parameters in count down timer to the time desired
CountDownTimer countDownTimer = new CountDownTimer(60*1000, 3) {
@Override
public void onTick(long millisUntilFinishedMain) {
countDownMain.setText(":" + millisUntilFinishedMain/1000);
//add possible sound here every tick
}
@Override
public void onFinish() {
Toast.makeText(getActivity(),"You lose", Toast.LENGTH_LONG).show();
//rest of text in method is trial
startActivity(new Intent(getActivity(), MainMenu.class ));
}
}.start();
}
}.start();
}
});
return view; //inflater.inflate(R.layout.fragment_level_one,container, false);
}
//getting screen size
public static Point getDisplaySize(@NonNull Context context){
Point point = new Point();
WindowManager manager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
manager.getDefaultDisplay().getSize(point);
return point;
}
//randomly move
public void randomMovement(ImageView img){
int x = new Random().nextInt(getDisplaySize(getActivity()).x);
int y = new Random().nextInt(getDisplaySize(getActivity()).y);
img.setY(y);
img.setX(x);
}
//creating timer
public void startRandomButton(final ImageView img){
Timer timer = new Timer();
timer.schedule(new TimerTask() {
@Override
public void run() {
getActivity().runOnUiThread(new Runnable() { //best method in the entire world-- use when trying to update ui in the background
@Override
public void run() {
randomMovement(img);
}
});
}
}, 0, 5000);
}
//listener for the moving ball
private final class ChoiceTouchListener implements View.OnTouchListener {
public boolean onTouch(View view, MotionEvent event){
//Calling Counter
textCount = (TextView) getView().findViewById(R.id.textViewCount);
//switch statement for different events
switch (event.getAction() & MotionEvent.ACTION_MASK){
case MotionEvent.ACTION_DOWN:
break;
case MotionEvent.ACTION_UP:
//this is where youre going to generate randmom location with id.setX(randomX) and id.setY(randomY)
randomMovement(img);
//Setting Counter to count when img is clicked
String countValue = textCount.getText().toString();
scoreCounter = Integer.parseInt(countValue);
scoreCounter++;
textCount.setText(String.valueOf(scoreCounter));
break;
case MotionEvent.ACTION_POINTER_DOWN:
break;
case MotionEvent.ACTION_POINTER_UP:
break;
}
//checking score
if(scoreCounter == 10 )
{
Toast.makeText(getActivity(),"You win", Toast.LENGTH_LONG).show();
}
viewer.invalidate();
return true;
}
}
}
正如您所看到的，上面发布的代码是我的片段的java代码。下面是片段的xml。
<?xml version="1.0" encoding="utf-8"?>
<!-- TODO: Update blank fragment layout -->
<RelativeLayout 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:id="@+id/view_level"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@drawable/levelbackgroundoptiontwo"
tools:context="com.example.name.inserttitlename.LevelOneFragment"
tools:layout_editor_absoluteX="0dp"
tools:layout_editor_absoluteY="81dp">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<Button
android:id="@+id/failureButton"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_alignParentTop="true"
android:background="@drawable/levelbackgroundoptiontwo"
android:visibility="visible" />
</RelativeLayout>
<TextView
android:id="@+id/textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_alignParentStart="true"
android:text="Version: 0.0.12"
android:textColor="#Ef9A9A"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
tools:layout_constraintBottom_creator="1"
tools:layout_constraintLeft_creator="1" />
<ImageView
android:id="@+id/imageView"
android:layout_width="61dp"
android:layout_height="80dp"
android:layout_alignParentBottom="true"
android:layout_alignParentStart="true"
android:layout_marginBottom="66dp"
app:layout_constraintHorizontal_bias="1.0"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:srcCompat="@drawable/clickerobject"
tools:layout_constraintLeft_creator="1"
tools:layout_constraintRight_creator="1"
tools:layout_constraintTop_creator="1" />
<TextView
android:id="@+id/textViewCount"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentEnd="true"
android:layout_alignParentTop="true"
android:fontFamily="casual"
android:text="0"
android:textColor="@android:color/white"
android:textSize="30sp"
android:textStyle="bold" />
<TextView
android:id="@+id/levelCounter"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBottom="@+id/textViewCount"
android:layout_alignParentStart="true"
android:layout_alignParentTop="true"
android:fontFamily="casual"
android:text="Level: 1"
android:textColor="@android:color/white"
android:textSize="30sp"
android:textStyle="bold" />
<TextView
android:id="@+id/countDownMain"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBottom="@+id/levelCounter"
android:layout_centerHorizontal="true"
android:fontFamily="casual"
android:text="60"
android:textColor="@android:color/white"
android:textSize="30sp"
android:textStyle="bold" />
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<Button
android:id="@+id/beginButton"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_alignParentStart="true"
android:layout_alignParentTop="true"
android:background="#80363636"
android:fontFamily="casual"
android:text="Tap anywhere to begin"
android:textColor="@android:color/white"
android:textSize="30sp"
android:textStyle="bold"
android:visibility="visible" />
</RelativeLayout>
<TextView
android:id="@+id/countDownBeginText"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
android:layout_marginBottom="213dp"
android:text="TextView"
android:textColor="@android:color/white"
android:textSize="35sp"
android:textStyle="bold"
android:visibility="visible"
tools:text="3" />
</RelativeLayout>
这里也是我调用片段的地方。
package com.example.name.insertitlename;
import android.app.Activity;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.view.View;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.widget.Button;
import android.widget.Toast;
/**
* Created by Marcus
*/
public class LevelsMenu extends FragmentActivity {
Button levelOne;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.levels_menu);
//creating the buttons
//Button levelOne;
//setting the button equal to buttons found on levels_menu.xml
levelOne = (Button) findViewById(R.id.levelone);
//button listener surrounding fragment call
levelOne.setOnClickListener(new View.OnClickListener(){
public void onClick(View v){
LevelOneFragment fragment = new LevelOneFragment();
FragmentManager manager = getSupportFragmentManager();
manager.beginTransaction().replace(R.id.levelsMainLayout, fragment, fragment.getTag()).commit();
}
});
}
}
这是我的logcat：
10-22 01:02:03.174 3165-3341/com.example.jon.tapmeifyoucan E/AndroidRuntime: FATAL EXCEPTION: Timer-0
Process: com.example.jon.tapmeifyoucan, PID: 3165
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v4.app.FragmentActivity.runOnUiThread(java.lang.Runnable)' on a null object reference
at com.example.jon.tapmeifyoucan.LevelOneFragment$3.run(LevelOneFragment.java:162)
at java.util.TimerThread.mainLoop(Timer.java:555)
at java.util.TimerThread.run(Timer.java:505)
10-22 01:02:03.290 3165-3183/com.example.jon.tapmeifyoucan D/EGL_emulation: eglMakeCurrent: 0xa77050c0: ver 3 0 (tinfo 0xa7703210)
10-22 01:02:03.374 3165-3183/com.example.jon.tapmeifyoucan D/EGL_emulation: eglMakeCurrent: 0xa77050c0: ver 3 0 (tinfo 0xa7703210)
我不确定我哪里出错了。我真的可以使用一些帮助，甚至可能对片段进行更多澄清。对于那些想要在原始活动中引用原始java代码的人，请将其发布在
下面//this consists of all the game logic
package com.example.name.insertitlename;
import android.content.Context;
import android.content.Intent;
import android.graphics.Point;
import android.os.CountDownTimer;
import android.support.annotation.NonNull;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.view.MotionEvent;
import android.view.ViewGroup;
import android.view.View.OnTouchListener;
import android.view.WindowManager;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.RelativeLayout;
import android.widget.TextView;
import android.widget.Toast;
import org.w3c.dom.Text;
import java.util.Random;
import java.util.Timer;
import java.util.TimerTask;
public class MainActivity extends AppCompatActivity {
//creating variables
private ImageView img;
private ImageView lava;
private ViewGroup rootLayout;
TextView textCount;
Button failButton;
Button beginButton;
TextView countDownBeginText;
private TextView countDownMain;
public int scoreCounter;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//creating viewables
rootLayout = (ViewGroup) findViewById(R.id.view_root);
img = (ImageView) rootLayout.findViewById(R.id.imageView);
failButton = (Button) rootLayout.findViewById(R.id.failureButton);
countDownMain = (TextView) findViewById(R.id.countDownMain);
countDownBeginText = (TextView) findViewById(R.id.countDownBeginText);
beginButton = (Button) findViewById(R.id.beginButton);
RelativeLayout.LayoutParams layoutParams = new RelativeLayout.LayoutParams(150, 150);
img.setLayoutParams(layoutParams);
img.setOnTouchListener(new ChoiceTouchListener());
//begin random movement
startRandomButton(img);
//setting up button for failure CORRECT TO TAKE YOU TO THE MAIN MENU
failButton.setOnClickListener(new View.OnClickListener(){
public void onClick(View v){
startActivity(new Intent(MainActivity.this, MainMenu.class));
}
});
//setting countdown text to 3
countDownBeginText.setText(":3");
//begin countdown from three
beginButton.setOnClickListener(new View.OnClickListener(){
public void onClick(View beginT) {
CountDownTimer countDownTimer = new CountDownTimer(3*1000, 3) {
@Override
public void onTick(long millisUntilFinished) {
countDownBeginText.setText(":" + millisUntilFinished/1000);
//add possible sound here every tick
}
@Override
public void onFinish() {
beginButton.setVisibility(View.INVISIBLE);
countDownBeginText.setVisibility(View.INVISIBLE);
//countdown from 60------- change parameters in count down timer to the time desired
CountDownTimer countDownTimer = new CountDownTimer(60*1000, 3) {
@Override
public void onTick(long millisUntilFinishedMain) {
countDownMain.setText(":" + millisUntilFinishedMain/1000);
//add possible sound here every tick
}
@Override
public void onFinish() {
Toast.makeText(MainActivity.this,"You lose", Toast.LENGTH_LONG).show();
//rest of text in method is trial
startActivity(new Intent(MainActivity.this, MainMenu.class ));
}
}.start();
}
}.start();
}
});
}
//getting screen size
public static Point getDisplaySize(@NonNull Context context){
Point point = new Point();
WindowManager manager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
manager.getDefaultDisplay().getSize(point);
return point;
}
//randomly move
public void randomMovement(ImageView img){
int x = new Random().nextInt(getDisplaySize(this).x);
int y = new Random().nextInt(getDisplaySize(this).y);
img.setY(y);
img.setX(x);
}
//creating timer
public void startRandomButton(final ImageView img){
Timer timer = new Timer();
timer.schedule(new TimerTask() {
@Override
public void run() {
runOnUiThread(new Runnable() { //best method in the entire world-- use when trying to update ui in the background
@Override
public void run() {
randomMovement(img);
}
});
}
}, 0, 5000);
}
//listener for the moving ball
private final class ChoiceTouchListener implements OnTouchListener{
public boolean onTouch(View view, MotionEvent event){
//Calling Counter
textCount = (TextView) findViewById(R.id.textViewCount);
//switch statement for different events
switch (event.getAction() & MotionEvent.ACTION_MASK){
case MotionEvent.ACTION_DOWN:
break;
case MotionEvent.ACTION_UP:
//this is where youre going to generate randmom location with id.setX(randomX) and id.setY(randomY)
randomMovement(img);
//Setting Counter to count when img is clicked
String countValue = textCount.getText().toString();
scoreCounter = Integer.parseInt(countValue);
scoreCounter++;
textCount.setText(String.valueOf(scoreCounter));
break;
case MotionEvent.ACTION_POINTER_DOWN:
break;
case MotionEvent.ACTION_POINTER_UP:
break;
}
//checking score
if(scoreCounter == 10 )
{
Toast.makeText(MainActivity.this,"You win", Toast.LENGTH_LONG).show();
}
rootLayout.invalidate();
return true;
}
}
}