通過捆綁傳遞值，並在另一個活動上獲得它

一切似乎工作，直到我啓動並決定輸入我的名字並按下按鈕開始遊戲時，似乎值沒有被傳遞到其他活動，任何人都可以幫助我解決這個問題，在eclipse luna fyi上做這個。通過捆綁傳遞值，並在另一個活動上獲得它

MainActivity：

public class MainActivity extends Activity { 
    private Button GameButton; 
    private EditText TextBox; 
    private String UserName; 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 
     TextBox = (EditText)findViewById(R.id.enterName); 
     GameButton = (Button)findViewById(R.id.gameStart); 
     GameButton.setOnClickListener(new View.OnClickListener() { 

      @Override 
     public void onClick(View v) { 
       UserName = TextBox.getText().toString(); 
       Intent g = new Intent(getBaseContext(),GameActivity.class); 
       g.putExtra(GameActivity.PlayerName, UserName); 
       startActivity(g); 

      } 
     }); 


    } 

    @Override 
    public boolean onCreateOptionsMenu(Menu menu) { 
     // Inflate the menu; this adds items to the action bar if it is present. 
     getMenuInflater().inflate(R.menu.main, menu); 
     return true; 
    } 

    @Override 
    public boolean onOptionsItemSelected(MenuItem item) { 
     // Handle action bar item clicks here. The action bar will 
     // automatically handle clicks on the Home/Up button, so long 
     // as you specify a parent activity in AndroidManifest.xml. 
     int id = item.getItemId(); 
     if (id == R.id.action_settings) { 
      return true; 
     } 
     return super.onOptionsItemSelected(item); 
    } 
}

GameActivity：

package com.example.battleships; 


public class GameActivity extends Activity { 
    private ImageView mMyImage1, mMyImage2, mMyImage3, mMyImage4, mMyImage5, 
      mMyImage6, mMyImage7, mMyImage8, mMyImage9, mMyImage10, mMyImage11, 
      mMyImage12, mMyImage13, mMyImage14, mMyImage15, mMyImage16, 
      mMyImage17, mMyImage18, mMyImage19, mMyImage20, mMyImage21, 
      mMyImage22, mMyImage23, mMyImage24, mMyImage25; 
    public static final String PlayerName = "com.example.battleships.Name"; 

    public ImageView[] mYimage = { mMyImage1, mMyImage2, mMyImage3, mMyImage4, 
      mMyImage5, mMyImage6, mMyImage7, mMyImage8, mMyImage9, mMyImage10, 
      mMyImage11, mMyImage12, mMyImage13, mMyImage14, mMyImage15, 
      mMyImage16, mMyImage17, mMyImage18, mMyImage19, mMyImage20, 
      mMyImage21, mMyImage22, mMyImage23, mMyImage24, mMyImage25 }; 

    private int[] nums = { 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 
      1, 1, 1, 1, 1, 1, 1, 1 }; 
    private int myCount = 0, Count = 8; 
    private String GamerName; 
    private TextView myText; 
    private Drawable bomb, clown; 

    Drawable startImage; 

    @Override 
    // Method 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_game); 
     GamerName = getIntent().getStringExtra(PlayerName); 
     myText = (TextView)findViewById(R.id.textView1); 
     myText.setText("Hi, " + GamerName + "! You have" + Count + "attempts."); 
     //..........

這裏是GameActivity佈局的xml：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
xmlns:tools="http://schemas.android.com/tools" 
android:layout_width="match_parent" 
android:layout_height="match_parent" 
android:paddingBottom="@dimen/activity_vertical_margin" 
android:paddingLeft="@dimen/activity_horizontal_margin" 
android:paddingRight="@dimen/activity_horizontal_margin" 
android:paddingTop="@dimen/activity_vertical_margin" 
tools:context="com.example.battleships.GameActivity" 
tools:ignore="UselessParent" > 

<GridLayout 
android:layout_width="match_parent" 
android:layout_height="match_parent" 
android:layout_marginTop="23dp" 
android:columnCount="5" 
android:rowCount="5" 
> 

<ImageView 
android:id="@+id/ImageView1" 
android:layout_width="60dp" 
android:layout_height="60dp" 
android:layout_column="0" 
android:layout_gravity="start|top" 
android:layout_row="0" 
android:onClick="action" 
android:contentDescription="@string/desc" /> 

<ImageView 
android:id="@+id/imageView2" 
android:layout_width="60dp" 
android:layout_height="60dp" 
android:layout_column="1" 
android:layout_gravity="start|top" 
android:layout_row="0" 
android:onClick="action" 

android:contentDescription="@string/desc" /> 

<ImageView 
android:id="@+id/imageView3" 
android:layout_width="60dp" 
android:layout_height="60dp" 
android:layout_column="2" 
android:layout_gravity="start|top" 
android:layout_row="0" 
android:onClick="action" 
android:contentDescription="@string/desc" /> 

<ImageView 
android:id="@+id/imageView4" 
android:layout_width="60dp" 
android:layout_height="60dp" 
android:layout_column="3" 
android:layout_gravity="start|top" 
android:layout_row="0" 
android:onClick="action" 
android:contentDescription="@string/desc"/> 

<ImageView 
android:id="@+id/imageView5" 
android:layout_width="60dp" 
android:layout_height="60dp" 
android:layout_column="4" 
android:layout_gravity="start|top" 
android:layout_row="0" 
android:onClick="action" 
android:contentDescription="@string/desc" /> 

<ImageView 
android:id="@+id/imageView6" 
android:layout_width="60dp" 
android:layout_height="60dp" 
android:layout_column="0" 
android:layout_gravity="start|top" 
android:layout_row="1" 
android:onClick="action" 
android:contentDescription="@string/desc" /> 

<ImageView 
android:id="@+id/imageView7" 
android:layout_width="60dp" 
android:layout_height="60dp" 
android:layout_column="1" 
android:layout_gravity="start|top" 
android:layout_row="1" 
android:onClick="action" 
android:contentDescription="@string/desc" /> 

<ImageView 
android:id="@+id/imageView8" 
android:layout_width="60dp" 
android:layout_height="60dp" 
android:layout_column="2" 
android:layout_gravity="start|top" 
android:layout_row="1" 
android:onClick="action" 
android:contentDescription="@string/desc" /> 

<ImageView 
android:id="@+id/imageView9" 
android:layout_width="60dp" 
android:layout_height="60dp" 
android:layout_column="3" 
android:layout_gravity="start|top" 
android:layout_row="1" 
android:onClick="action" 
android:contentDescription="@string/desc" /> 

<ImageView 
android:id="@+id/imageView10" 
android:layout_width="60dp" 
android:layout_height="60dp" 
android:layout_column="4" 
android:layout_gravity="start|top" 
android:layout_row="1" 
android:onClick="action" 
android:contentDescription="@string/desc" /> 

<ImageView 
android:id="@+id/imageView11" 
android:layout_width="60dp" 
android:layout_height="60dp" 
android:layout_column="0" 
android:layout_gravity="start|top" 
android:layout_row="2" 
android:onClick="action" 
android:contentDescription="@string/desc" /> 

<ImageView 
android:id="@+id/imageView12" 
android:layout_width="60dp" 
android:layout_height="60dp" 
android:layout_column="1" 
android:layout_gravity="start|top" 
android:layout_row="2" 
android:onClick="action" 
android:contentDescription="@string/desc" /> 

<ImageView 
android:id="@+id/imageView13" 
android:layout_width="60dp" 
android:layout_height="60dp" 
android:layout_column="2" 
android:layout_gravity="start|top" 
android:layout_row="2" 
android:onClick="action" 
android:contentDescription="@string/desc" /> 

<ImageView 
android:id="@+id/imageView14" 
android:layout_width="60dp" 
android:layout_height="60dp" 
android:layout_column="3" 
android:layout_gravity="start|top" 
android:layout_row="2" 
android:onClick="action" 
android:contentDescription="@string/desc" /> 

<ImageView 
android:id="@+id/imageView15" 
android:layout_width="60dp" 
android:layout_height="60dp" 
android:layout_column="4" 
android:layout_gravity="start|top" 
android:layout_row="2" 
android:onClick="action" 
android:contentDescription="@string/desc" /> 

<ImageView 
android:id="@+id/imageView16" 
android:layout_width="60dp" 
android:layout_height="60dp" 
android:layout_column="0" 
android:layout_gravity="start|top" 
android:layout_row="3" 
android:onClick="action" 
android:contentDescription="@string/desc" /> 

<ImageView 
android:id="@+id/imageView17" 
android:layout_width="60dp" 
android:layout_height="60dp" 
android:layout_column="1" 
android:layout_gravity="start|top" 
android:layout_row="3" 
android:onClick="action" 
android:contentDescription="@string/desc" /> 

<ImageView 
android:id="@+id/imageView18" 
android:layout_width="60dp" 
android:layout_height="60dp" 
android:layout_column="2" 
android:layout_gravity="start|top" 
android:layout_row="3" 
android:onClick="action" 
android:contentDescription="@string/desc" /> 

<ImageView 
android:id="@+id/imageView19" 
android:layout_width="60dp" 
android:layout_height="60dp" 
android:layout_column="3" 
android:layout_gravity="start|top" 
android:layout_row="3" 
android:onClick="action" 
android:contentDescription="@string/desc" /> 

<ImageView 
android:id="@+id/imageView20" 
android:layout_width="60dp" 
android:layout_height="60dp" 
android:layout_column="4" 
android:layout_gravity="start|top" 
android:layout_row="3" 
android:onClick="action" 
android:contentDescription="@string/desc" /> 

<ImageView 
android:id="@+id/imageView21" 
android:layout_width="60dp" 
android:layout_height="60dp" 
android:layout_column="0" 
android:layout_gravity="start|top" 
android:layout_row="4" 
android:onClick="action" 
android:contentDescription="@string/desc" /> 

<ImageView 
android:id="@+id/imageView22" 
android:layout_width="60dp" 
android:layout_height="60dp" 
android:layout_column="1" 
android:layout_gravity="start|top" 
android:layout_row="4" 
android:onClick="action" 
android:contentDescription="@string/desc" /> 

<ImageView 
android:id="@+id/imageView23" 
android:layout_width="60dp" 
android:layout_height="60dp" 
android:layout_column="2" 
android:layout_gravity="start|top" 
android:layout_row="4" 
android:onClick="action" 
android:contentDescription="@string/desc" /> 

<ImageView 
android:id="@+id/imageView24" 
android:layout_width="60dp" 
android:layout_height="60dp" 
android:layout_column="3" 
android:layout_gravity="start|top" 
android:layout_row="4" 
android:onClick="action" 
android:contentDescription="@string/desc" /> 

<ImageView 
android:id="@+id/imageView25" 
android:layout_width="60dp" 
android:layout_height="60dp" 
android:layout_column="4" 
android:layout_gravity="start|top" 
android:layout_row="4" 
android:onClick="action" 
android:contentDescription="@string/desc" /> 

</GridLayout> 

</RelativeLayout>

這裏是堆棧跟蹤：

05-03 17:05:18.282: E/AndroidRuntime(15872): FATAL EXCEPTION: main 
05-03 17:05:18.282: E/AndroidRuntime(15872): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.battleships/com.example.battleships.GameActivity}: java.lang.NullPointerException 
05-03 17:05:18.282: E/AndroidRuntime(15872): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2261) 
05-03 17:05:18.282: E/AndroidRuntime(15872): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2311) 
05-03 17:05:18.282: E/AndroidRuntime(15872): at android.app.ActivityThread.access$600(ActivityThread.java:149) 
05-03 17:05:18.282: E/AndroidRuntime(15872): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1293) 
05-03 17:05:18.282: E/AndroidRuntime(15872): at android.os.Handler.dispatchMessage(Handler.java:99) 
05-03 17:05:18.282: E/AndroidRuntime(15872): at android.os.Looper.loop(Looper.java:137) 
05-03 17:05:18.282: E/AndroidRuntime(15872): at android.app.ActivityThread.main(ActivityThread.java:5214) 
05-03 17:05:18.282: E/AndroidRuntime(15872): at java.lang.reflect.Method.invokeNative(Native Method) 
05-03 17:05:18.282: E/AndroidRuntime(15872): at java.lang.reflect.Method.invoke(Method.java:525) 
05-03 17:05:18.282: E/AndroidRuntime(15872): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:739) 
05-03 17:05:18.282: E/AndroidRuntime(15872): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:555) 
05-03 17:05:18.282: E/AndroidRuntime(15872): at dalvik.system.NativeStart.main(Native Method) 
05-03 17:05:18.282: E/AndroidRuntime(15872): Caused by: java.lang.NullPointerException 
05-03 17:05:18.282: E/AndroidRuntime(15872): at com.example.battleships.GameActivity.onCreate(GameActivity.java:56) 
05-03 17:05:18.282: E/AndroidRuntime(15872): at android.app.Activity.performCreate(Activity.java:5133) 
05-03 17:05:18.282: E/AndroidRuntime(15872): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087) 
05-03 17:05:18.282: E/AndroidRuntime(15872): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2225) 
05-03 17:05:18.282: E/AndroidRuntime(15872): ... 11 mo

來源

2015-05-03 Kathar Abdillwahid

這是我得到的錯誤。 http://justpaste.it/kwpq –

http://jpst.it/yDNZ感謝幫助。 –

看起來像你剛纔忘了textView1在activity_game.xml文件。

只需將TextView添加到您的xml文件中，那應該可以清除您收到的NullPointerException。

把GridView的TextView外：

<TextView 
     android:id="@+id/textView1" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" /> 

    <GridLayout 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" 
     android:layout_marginTop="23dp" 
     android:columnCount="5" 
     android:rowCount="5" 
     >

來源

2015-05-03 21:08:28

非常感謝，天啊，甚至沒有注意到這一點。 –

您可以使用SharedPreferences來做到這一點。使用SharedPreferences是一種簡單的方法來存儲和檢索整個類中的基元或字符串和讓它們在會話之間保持不變。

要使用它們，您需要爲SharedPreferences.Editor（用於添加值）或SharedPreferences對象（用於檢索值）。該import聲明這些對象是：

import android.content.SharedPreferences;

或

import android.content.SharedPreferences.Editor;

要設置值，使用此代碼：

：

SharedPreferences.Editor editor = getSharedPreferences("preferences (or whatever you want)", MODE_PRIVATE).edit(); 
editor.putString("username", UserName); 
editor.commit();

要從任何其他類檢索值

SharedPreferences preferences = getSharedPreferences("preferences (or whatever you want)", MODE_PRIVATE); 
GamerName = preferences.getString("username", "Value to put in case there is an error");

如果您不希望值會話之間，簡單地把這個代碼塊在MainActivity在onCreate方法：

SharedPreferences.Editor resetter = getSharedPreferences("preferences (or whatever you want)", MODE_PRIVATE); 
resetter.remove("username"); 
resetter.commit();

來源

2015-05-03 19:53:49

通過捆綁傳遞值，並在另一個活動上獲得它

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