通過Parcelable傳遞對象，但獲取NULL對象

Question

我是triyn來實現Parcle數據並通過Intent將它發送給其他類，但獲取NULL對象我是Android新手，如果對不起，那可能會有一些愚蠢的錯誤。按鈕過去了...... Cretaed對象和意圖單擊

public class ParceableExampleActivity extends Activity implements View.OnClickListener { 


    /** Called when the activity is first created. */ 
    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.main); 
     Button button1 = (Button)findViewById(R.id.button1); 
     button1.setOnClickListener(this); 

    } 
    @Override 
    public void onClick(View v) { 
     switch(v.getId()){ 
     case R.id.button1: 
      ParcelData p = new ParcelData(); 
      p.setFirstName("Kumar"); 
      p.setAddedBy(3); 
      Intent n = new Intent(this,ResultActivity.class); 
      n.putExtra("data", p); 
      startActivity(n); 

     } 

    } 
} 

Parceldata它實現pacelclass

public class ParcelData implements Parcelable { 

    private String firstName ; 
    private int addedBy ; 
    //private UUID guid ; 

    private static final String TAG = "TEST" ; 
    public ParcelData() { 
     firstName=null ; 
     addedBy=0; 
    // guid=null; 
    } 

    public String getFirstName() { 
     return firstName; 
    } 
    public void setFirstName(String firstName) { 
     this.firstName = firstName; 
    } 
    public int getAddedBy() { 
     return addedBy; 
    } 
    public void setAddedBy(int addedBy) { 
     this.addedBy = addedBy; 
    } 

    public static final Parcelable.Creator CREATOR = new Parcelable.Creator() { 
     public Parcelable createFromParcel(Parcel in) { 
         return new ParcelData(); 
     } 

     @Override 
     public Parcelable[] newArray(int size) { 
      return new Parcelable[size]; 
     } 
    } ; 



    public void writeToParcel(Parcel dest, int flags) { 
     Log.v(TAG, "writeToParcel..."+ flags); 

     dest.writeString(firstName); 
     dest.writeInt(addedBy); 


    } 

    public void ParcelData(Parcel in){ 
     readFromParcel(in); 
    } 

    @Override 
    public int describeContents() { 
     // TODO Auto-generated method stub 
     return 0; 
    } 

    private void readFromParcel(Parcel in) { 

     firstName= in.readString(); 
     addedBy= in.readInt(); 
    } 

    } 

接收對象

public class ResultActivity extends Activity implements View.OnClickListener { 



     /** Called when the activity is first created. */ 
     @Override 
     public void onCreate(Bundle savedInstanceState) { 
      super.onCreate(savedInstanceState); 
      setContentView(R.layout.main); 
      Button button1 = (Button)findViewById(R.id.button2); 
      button1.setOnClickListener(this); 
     } 
     @Override 
     public void onClick(View v) { 
      switch(v.getId()){ 
      case R.id.button2: 
       Bundle b = getIntent().getExtras(); 
       ParcelData result_p=b.getParcelable("data"); 
       Log.v("RESULT", "result of Parcel..."+ result_p.getFirstName()); 
       Log.v("RESULT", "result of Parcel..."+ result_p.getAddedBy()); 

      } 

     } 
    } 

但日誌的結果是NULL

Answer 1

這必須是一個構造函數。您必須移除void：

public ParcelData(Parcel in){ 
    readFromParcel(in); 
} 

否則它將被視爲一種方法，並未被使用。

造物主看起來像這樣：

public static final Parcelable.Creator<ParcelData> CREATOR = new Parcelable.Creator<ParcelData>() { 
    public ParcelData createFromParcel(Parcel source) { 
     return new ParcelData(source); 
    } 
    public ParcelData[] newArray(int size) { 
     return new ParcelData[size]; 
    } 
} 

@Override 
public ParcelData[] newArray(int size) { 
    return new ParcelData[size]; 
} 

你也不需要默認構造函數。無論如何，變量都被初始化爲這些值。我不知道它是否會導致框架問題。

//remove 
public ParcelData() { 
    firstName=null ; 
    addedBy=0; 
// guid=null; 
} 

在describeContents如果您使用的hashCode它可能會幫助：

@Override 
public int describeContents() { 
    return hashCode(); 
}