setText make apk崩溃

问题描述：

我正在尝试开发一个非常简单的apk。
我使用textView来显示两个团队的名称，我在之前的活动中输入（带有打开此活动的意图）。当我尝试使用setText来显示这些团队的名称apk崩溃。setText make apk崩溃

这是类崩溃：

public class MatchPage extends Activity { 
private String locali= null; 
private String ospiti= null; 
private TextView localiTV; 
private TextView ospitiTV; 
private MatchRugby partita; 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState);  
    setContentView(R.layout.match); 
    localiTV =(TextView) findViewById(R.id.localiTV); 
    ospitiTV =(TextView) findViewById(R.id.ospitiTV); 
    getLocali(); 
    getOspiti(); 
    createMatch(); 



    localiTV.setText("Locali /n"+ partita.teamA.getName()); 
    ospitiTV.setText("Ospiti /n"+ partita.teamB.getName()); 




} 

/** 
* Prende il nome della squadra locale dall'intent 
* @return 
*/ 
public String getLocali(){ 
    Intent matchStart = getIntent(); 
    String locali = matchStart.getStringExtra(NewMatchPage.LOCALI); 
    return locali; 
} 

/** 
* prende il nome della squadra ospite dall'intent 
* @return 
*/ 
public String getOspiti(){ 
    Intent matchStart = getIntent(); 
    String ospiti = matchStart.getStringExtra(NewMatchPage.OSPITI); 
    return ospiti; 
} 

public MatchRugby createMatch(){ 
    TeamRugby teamLocali= new TeamRugby(locali); 
    TeamRugby teamOspiti= new TeamRugby(ospiti); 
    MatchRugby partita= new MatchRugby(teamLocali, teamOspiti); 
    return partita; 
} 
    }

这是XML：

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
android:layout_width="match_parent" 
android:layout_height="match_parent" 
android:orientation="vertical" > 

<TextView 
    android:id="@+id/localiTV" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 

    android:textAppearance="?android:attr/textAppearanceLarge" /> 


<TextView 
    android:id="@+id/ospitiTV" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 

    android:textAppearance="?android:attr/textAppearanceLarge" /> 

</LinearLayout>

这是送的意图类：

public class NewMatchPage extends Activity { 

public static final String LOCALI = null; 
public static final String OSPITI = null; 
    private Button startMatch; 
protected void onCreate(Bundle savedInstanceState) { 

    super.onCreate(savedInstanceState); 
    setContentView(R.layout.new_match); 

    startMatch= (Button) findViewById(R.id.startMatch); 
     startMatch.setOnClickListener(new View.OnClickListener(){ 


      public void onClick(View arg0) { 
       startMatch(); 

      } 

     }); 
} 

public void startMatch(){ 
    Intent startMatch= new Intent(this, MatchPage.class); 

    //Prendo il testo scritto nella casella locali e la porto nella partita 
    EditText locali= (EditText) findViewById(R.id.Locali); 
    String locali1 = locali.getText().toString(); 
    startMatch.putExtra(LOCALI, locali1); 
    //Prendo il testo scritto nella casella ospiti e la porto nella partita 
    EditText ospiti= (EditText) findViewById(R.id.Ospiti); 
    String ospiti1 = ospiti.getText().toString(); 
    startMatch.putExtra(OSPITI, ospiti1); 
    //inizio la partita 
    startActivity(startMatch); 
} 

    }

最后那是logcat日志：

04-24 16:49:08.928: W/dalvikvm(1377): threadid=1: thread exiting with uncaught exception (group=0x409c01f8) 
    04-24 16:49:08.958: E/AndroidRuntime(1377): FATAL EXCEPTION: main 
    04-24 16:49:08.958: E/AndroidRuntime(1377): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.gmail.david.corsalini.sportscout/com.gmail.david.corsalini.sportscout.MatchPage}: java.lang.NullPointerException 
    04-24 16:49:08.958: E/AndroidRuntime(1377):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1956) 
    04-24 16:49:08.958: E/AndroidRuntime(1377):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981) 
    04-24 16:49:08.958: E/AndroidRuntime(1377):  at android.app.ActivityThread.access$600(ActivityThread.java:123) 
    04-24 16:49:08.958: E/AndroidRuntime(1377):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147) 
    04-24 16:49:08.958: E/AndroidRuntime(1377):  at android.os.Handler.dispatchMessage(Handler.java:99) 
    04-24 16:49:08.958: E/AndroidRuntime(1377):  at android.os.Looper.loop(Looper.java:137) 
    04-24 16:49:08.958: E/AndroidRuntime(1377):  at android.app.ActivityThread.main(ActivityThread.java:4424) 
    04-24 16:49:08.958: E/AndroidRuntime(1377):  at java.lang.reflect.Method.invokeNative(Native Method) 
    04-24 16:49:08.958: E/AndroidRuntime(1377):  at java.lang.reflect.Method.invoke(Method.java:511) 
    04-24 16:49:08.958: E/AndroidRuntime(1377):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784) 
    04-24 16:49:08.958: E/AndroidRuntime(1377):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551) 
    04-24 16:49:08.958: E/AndroidRuntime(1377):  at dalvik.system.NativeStart.main(Native Method) 
    04-24 16:49:08.958: E/AndroidRuntime(1377): Caused by: java.lang.NullPointerException 
    04-24 16:49:08.958: E/AndroidRuntime(1377):  at com.gmail.david.corsalini.sportscout.MatchPage.onCreate(MatchPage.java:25) 
    04-24 16:49:08.958: E/AndroidRuntime(1377):  at android.app.Activity.performCreate(Activity.java:4465) 
    04-24 16:49:08.958: E/AndroidRuntime(1377):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049) 
    04-24 16:49:08.958: E/AndroidRuntime(1377):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1920) 
    04-24 16:49:08.958: E/AndroidRuntime(1377):  ... 11 more

MatchRugby类

public class MatchRugby { 
public TeamRugby teamA; 
public TeamRugby teamB; 

/** 
* Costruttore della partita 
*/ 
public MatchRugby(TeamRugby teamA, TeamRugby teamB){ 
    this.teamA=teamA; 
    this.teamB=teamB; 
} 

/** 
* @return the teamA 
*/ 
public TeamRugby getTeamA() { 
    return teamA; 
} 


/** 
* @param teamA the teamA to set 
*/ 
public void setTeamA(TeamRugby teamA) { 
    this.teamA = teamA; 
} 


/** 
* @return the teamB 
*/ 
public TeamRugby getTeamB() { 
    return teamB; 
} 


/** 
* @param teamB the teamB to set 
*/ 
public void setTeamB(TeamRugby teamB) { 
    this.teamB = teamB; 
} 


public void EndOfMatch(){ 
    //nothing to do with the problem 
    } 
}

答

您的变量范围是全部关闭。设置你的班级是这样的：

public class MatchPage extends Activity { 
private String locali= null; 
private String ospiti= null; 
private TextView localiTV; 
private TextView ospitiTV; 
private MatchRugby partita; 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState);  
    setContentView(R.layout.match); 
    localiTV =(TextView) findViewById(R.id.localiTV); 
    ospitiTV =(TextView) findViewById(R.id.ospitiTV); 
    getLocali(); 
    getOspiti(); 
    createMatch(); 

    localiTV.setText("Locali /n"+ partita.teamA.getName()); 
    ospitiTV.setText("Ospiti /n"+ partita.teamB.getName()); 

} 

/** 
* Prende il nome della squadra locale dall'intent 
* @return 
*/ 
public String getLocali(){ 
    if (locali == null) { 
     Intent matchStart = getIntent(); 
     locali = matchStart.getStringExtra(NewMatchPage.LOCALI); 
    } 
    return locali; 
} 

/** 
* prende il nome della squadra ospite dall'intent 
* @return 
*/ 
public String getOspiti(){ 
    if (ospiti == null) { 
     Intent matchStart = getIntent(); 
     ospiti = matchStart.getStringExtra(NewMatchPage.OSPITI); 
    } 
    return ospiti; 
} 

public MatchRugby createMatch(){ 
    TeamRugby teamLocali= new TeamRugby(locali); 
    TeamRugby teamOspiti= new TeamRugby(ospiti); 
    partita = new MatchRugby(teamLocali, teamOspiti); 
    return partita 
} 

    private String locali 
    private String ospiti 
    private MatchRugby partita 
}

我没有看到你在哪里改变了代码，你只是在最后添加了locali ospiti和partita的副本，或者我没有找到什么东西？ – 2012-04-24 18:01:47

@DavidCorsalini对不起，我没有看到你的声明在顶部。你可以在最后忽略它们。主要变化在于：MatchRugby partita = new MatchRugby（teamLocali，teamOspiti）;''partita = new MatchRugby（teamLocali，teamOspiti）;'。通过再次添加类型，你创建了一个局部变量，它只存在于你的函数中，然后被销毁。将类型点移除到类级变量。为locali和ospiti做同样的工作 – JRaymond 2012-04-24 18:06:03

这样做的伎俩，谢谢，现在我只需要找到我在哪里搞砸了，并在localiTV上使用setText的ospiti值！ – 2012-04-24 19:14:27

答

java.lang.NullPointerException 
    at com.gmail.david.corsalini.sportscout.MatchPage.onCreate(MatchPage.java:25)

似乎是你变奏曲对象是从上述错误空。从你的代码中要初始化它

createMatch();

下面一行替换上述方法

partita = createMatch();

您也可以更改下面的代码::

public void createMatch(){ 
    TeamRugby teamLocali= new TeamRugby(locali); 
    TeamRugby teamOspiti= new TeamRugby(ospiti); 
    partita= new MatchRugby(teamLocali, teamOspiti); 
}

通过这样做，我得到一个错误，因为createMatch的返回类型不是MatchRugby（但是无效）。只需用partita = createMatch（）替换方法调用;我得到一个工作活动，但textview给我“locali null”和“ospiti null”。 – 2012-04-24 18:03:40

您可以添加您的MatchRugby类，可能需要更改它在主要问题上添加 – 2012-04-24 18:12:31

。 – 2012-04-24 19:14:36

答

你有NullPointerException在onCreate方法的MatchPage类的＃25行。不知道你发布的代码究竟是哪一行，但我最好的猜测是你的findViewById调用找不到任何东西。

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