我一直在为Android开发游戏，我想把高分放入。我认为这段代码应该正常工作，并且无法理解为什么它不是。我已将其设置为按下菜单按钮时会打开一个对话框，供用户输入其名称。这可以工作但是当你按下确定时，应用程序崩溃了。它崩溃的行是ArrayList<Player> players= fs.getScores();
以下是活动类的代码，它崩溃的地方：
package com.example.game;
import java.util.Collections;
import android.os.Bundle;
import android.app.Activity;
import android.view.KeyEvent;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.Window;
import android.widget.TextView;
import java.util.ArrayList;
import android.app.AlertDialog;
import android.app.Dialog;
import android.content.DialogInterface;
import android.widget.EditText;
import android.view.LayoutInflater;
public class MyGame extends Activity {
GameView gv;
private final int DIALOG_TEXT_ENTRY = 1;
Filestore fs;
private String GAME_KEY= "game_key";
private Bundle sis;
TextView hscores;
String name = "";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
gv = new GameView(this);
setContentView(gv);
gv.setStarted(true);
}
@Override
public boolean onKeyDown(int keyCode, KeyEvent msg) {
if (keyCode==KeyEvent.KEYCODE_DPAD_RIGHT)
gv.setSpriteState(2);
if (keyCode==KeyEvent.KEYCODE_DPAD_LEFT)
gv.setSpriteState(1);
if (keyCode == KeyEvent.KEYCODE_MENU)
showDialog(DIALOG_TEXT_ENTRY);
return true;
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
super.onCreateOptionsMenu(menu);
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.my_game, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle item selection
switch (item.getItemId()) {
case R.id.new_game:
gv = new GameView(this);
gv.setStarted(true);
setContentView(gv);
return true;
case R.id.save:
showDialog(DIALOG_TEXT_ENTRY);
return true;
case R.id.quit:
finish();
return true;
case R.id.highscores:
setContentView(R.layout.highscores);
hscores = (TextView) findViewById(R.id.myhighscores);
ArrayList<Player> players= fs.getScores();
if(!(players==null))
{
Collections.sort(players);
String s=String.format("%15s%15s","NAME","SCORE\n");
for(Player p:players)
{
s+=String.format("%15s%15s",p.getName(),
p.getScore()+"\n");
}
hscores.setText(s);
}
return true;
default:
return super.onOptionsItemSelected(item);
}
}
@Override
protected Dialog onCreateDialog(int id) {
switch (id) {
case DIALOG_TEXT_ENTRY:
LayoutInflater factory = LayoutInflater.from(this);
final View textEntryView = factory.inflate(R.layout.save, null);
final EditText t = (EditText) textEntryView.findViewById(R.id.save_edit);
name = t.toString();
return new AlertDialog.Builder(MyGame.this)
.setIcon(R.drawable.alert_dialog_icon)
.setTitle(R.string.alert_dialog_save_title)
.setView(textEntryView)
.setPositiveButton(R.string.alert_dialog_ok,
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog,
int whichButton) {
Player p= new Player(t.getText().toString(),gv.getTime());
ArrayList<Player> players= fs.getScores();
if(players==null)
players= new ArrayList<Player>();
players.add(p);
fs.saveScores(players);
}
})
.setNegativeButton(R.string.alert_dialog_cancel,
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog,
int whichButton) {
}
}).create();
}
return null;
}
public void onClick(DialogInterface dialog,
int whichButton) {
Player p= new Player(name,gv.getTime());
ArrayList<Player> players= fs.getScores();
if(players==null)
players= new ArrayList<Player>();
players.add(p);
fs.saveScores(players);
}
@Override
public void onSaveInstanceState(Bundle outState){
super.onSaveInstanceState(outState);
outState.putBundle(GAME_KEY, gv.saveState());
sis=outState;
}
}
这是logcat：
07-08 20:56:24.799: E/AndroidRuntime(1649): FATAL EXCEPTION: main
07-08 20:56:24.799: E/AndroidRuntime(1649): java.lang.NullPointerException
07-08 20:56:24.799: E/AndroidRuntime(1649): at com.example.game.MyGame$1.onClick(MyGame.java:117)
07-08 20:56:24.799: E/AndroidRuntime(1649): at com.android.internal.app.AlertController$ButtonHandler.handleMessage(AlertController.java:159)
07-08 20:56:24.799: E/AndroidRuntime(1649): at android.os.Handler.dispatchMessage(Handler.java:99)
07-08 20:56:24.799: E/AndroidRuntime(1649): at android.os.Looper.loop(Looper.java:123)
07-08 20:56:24.799: E/AndroidRuntime(1649): at android.app.ActivityThread.main(ActivityThread.java:3687)
07-08 20:56:24.799: E/AndroidRuntime(1649): at java.lang.reflect.Method.invokeNative(Native Method)
07-08 20:56:24.799: E/AndroidRuntime(1649): at java.lang.reflect.Method.invoke(Method.java:507)
07-08 20:56:24.799: E/AndroidRuntime(1649): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867)
07-08 20:56:24.799: E/AndroidRuntime(1649): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:625)
07-08 20:56:24.799: E/AndroidRuntime(1649): at dalvik.system.NativeStart.main(Native Method)
我试图包括我能想到的一切，但我是新手。任何帮助都会非常感激。
答案 0 :(得分：1)
ArrayList<Player> players= fs.getScores();
似乎fs指向null并导致NullPointerException。
在您的代码中，您无法将fs指向有效的实例/对象。
答案 1 :(得分：0)
字段fs（文件存储）未初始化。您需要先创建（或获取）实例，可能就像在GameView方法中初始化onCreate一样。