點擊「右」按鈕後，應用程序停止

Question

我開始一個活動（通過意向，我給它putExtra（字符串）：紅，黃，綠或藍）

currentColor有顏色我不不想被點擊。

我有4個按鈕（我從源刪除它，因爲我不認爲你需要它）。

public class ColorChooser extends Activity implements android.view.View.OnClickListener { 
String currentColor; 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setTitle("Choose a color"); 
    setContentView(R.layout.color_chooser); 
    setFinishOnTouchOutside(false); 

    currentColor = getIntent().getExtras().getString("CurrentColor"); 
} 

@Override 
public void onBackPressed() { 
} 

@Override 
public void onClick(View v) { 

    Intent returnIntent = new Intent(); 
    String picked = ""; 

    boolean ok = true; 
    while(ok) { 
     switch (v.getId()) { 
      case R.id.btnRed: 
       picked = "RED"; 
       break; 
      case R.id.btnYellow: 
       picked = "YELLOW"; 
       break; 
      case R.id.btnGreen: 
       picked = "GREEN"; 
       break; 
      case R.id.btnBlue: 
       picked = "BLUE"; 
       break; 
     } 
     if(picked.equals(currentColor)){ 
      Toast.makeText(getApplicationContext(), "Choose other color please", Toast.LENGTH_LONG).show(); 
     } else { 
      returnIntent.putExtra("Color", picked); 
      ok = false; 
     } 
    } 
    setResult(RESULT_OK, returnIntent); 
    finish(); 
} 

}

在我的清單我有這個。所以它顯示爲一個對話框。我必須選擇一種顏色。現在

<activity 
      android:name=".ColorChooser" 
      android:theme="@android:style/Theme.Dialog" 
      /> 

我的問題是：如果我選擇一種顏色，多數民衆贊成= currentColor，其優良的！但是，如果我選擇與currentColor相同的顏色，該應用會停止。應用中的按鈕顯示爲點擊（黃色）。 我認爲這是因爲我用了。我不知道我能做到這一點，我應該選擇一種顏色，直到它！= currentColor

05-21 18:33:09.782 1873-1873/com.example.thm_wip1.uno E/AndroidRuntime﹕ FATAL EXCEPTION: main 
    java.lang.ExceptionInInitializerError 
      at com.example.thm_wip1.uno.Deck.<init>(Deck.java:25) 
      at com.example.thm_wip1.uno.MultiplayerActivity.onCreate(MultiplayerActivity.java:52) 
      at android.app.Activity.performCreate(Activity.java:5008) 
      at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079) 
      at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2023) 
      at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084) 
      at android.app.ActivityThread.access$600(ActivityThread.java:130) 
      at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195) 
      at android.os.Handler.dispatchMessage(Handler.java:99) 
      at android.os.Looper.loop(Looper.java:137) 
      at android.app.ActivityThread.main(ActivityThread.java:4745) 
      at java.lang.reflect.Method.invokeNative(Native Method) 
      at java.lang.reflect.Method.invoke(Method.java:511) 
      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786) 
      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553) 
      at dalvik.system.NativeStart.main(Native Method) 
Caused by: java.lang.NullPointerException 
      at com.example.thm_wip1.uno.CardValue.<clinit>(CardValue.java:13) 
            at com.example.thm_wip1.uno.Deck.<init>(Deck.java:25) 
            at com.example.thm_wip1.uno.MultiplayerActivity.onCreate(MultiplayerActivity.java:52) 
            at android.app.Activity.performCreate(Activity.java:5008) 
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079) 
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2023) 
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084) 
            at android.app.ActivityThread.access$600(ActivityThread.java:130) 
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195) 
            at android.os.Handler.dispatchMessage(Handler.java:99) 
            at android.os.Looper.loop(Looper.java:137) 
            at android.app.ActivityThread.main(ActivityThread.java:4745) 
            at java.lang.reflect.Method.invokeNative(Native Method) 
            at java.lang.reflect.Method.invoke(Method.java:511) 
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786) 
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553) 
            at dalvik.system.NativeStart.main(Native Method) 

Answer 1

下面改變你的onClick像。從onClick方法中刪除while循環。

@Override 
public void onClick(View v) { 

    Intent returnIntent = new Intent(); 
    String picked = ""; 

    switch (v.getId()) { 
      case R.id.btnRed: 
       picked = "RED"; 
       break; 
      case R.id.btnYellow: 
       picked = "YELLOW"; 
       break; 
      case R.id.btnGreen: 
       picked = "GREEN"; 
       break; 
      case R.id.btnBlue: 
       picked = "BLUE"; 
       break; 
    } 
    if(picked.equals(currentColor)){ 
      //If picked color is same as currentColor do nothig 
      Toast.makeText(getApplicationContext(), "Choose other color please", Toast.LENGTH_LONG).show(); 
    } else { 
     //return pikced color 
     returnIntent.putExtra("Color", picked); 
     setResult(RESULT_OK, returnIntent); 
     finish(); 
    } 
}