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我做了一個java類'商店'，它存儲了我通過2個spinners n一個edittext給出的值...我使用parcelable將該類的對象傳遞給中間類Spinpizza。 java後面跟着Bill.java ....它顯示出正確的輸出直到SpinPizza ..（顯示通過spinner n edittext輸入的值），但它給了Bill.java中的NULL POINTER EXCEPTION :-(請幫助我...我米堅持這一超過4天數。使用Parcelable時空指針異常
這裏是我的代碼...
Store.java
package com.Lak;
import android.os.Parcel;
import android.os.Parcelable;
public class store implements Parcelable {
/**
*
*/
private static final long serialVersionUID = 1L;
private String pizzaname;
private String pizzasize;
private int n;
public void setOrder(String name,String size,int qty)
{
pizzaname = name;
pizzasize = size;
n = qty;
}
public String getPizzaName()
{
return pizzaname;
}
public int getQuantity()
{return n;}
public String getPizzaSize() {
// TODO Auto-generated method stub
return pizzasize;
}
public int describeContents() {
// TODO Auto-generated method stub
return 0;
}
@SuppressWarnings("rawtypes")
public static final Parcelable.Creator CREATOR = new Parcelable.Creator() {
public store createFromParcel(Parcel in) {
return new store(in);
}
public store[] newArray(int size) {
return new store[size];
}
};
public void writeToParcel(Parcel dest, int flags) {
dest.writeInt(n);
dest.writeString(pizzaname);
dest.writeString(pizzasize);
}
public store()
{}
public store(Parcel source){
/*
* Reconstruct from the Parcel
*/
n = source.readInt();
pizzaname = source.readString();
pizzasize = source.readString();
}
/** Called when the activity is first created. */
}
（SpinPizza.java）
package com.Lak;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.KeyEvent;
import android.view.View;
import android.view.View.OnKeyListener;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Spinner;
import android.widget.TextView;
import android.widget.Toast;
public class SpinPizza extends Activity{
/**
*
*/
private static final long serialVersionUID = 1L;
store B[]= new store[10];
Spinner s=null,s1=null;
EditText edittext=null;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.drop);
s = (Spinner) findViewById(R.id.spinner);
ArrayAdapter<?> adapter = ArrayAdapter.createFromResource(
this, R.array.pizzaarray, android.R.layout.simple_spinner_item);
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
s.setAdapter(adapter);
s1 = (Spinner) findViewById(R.id.spinner1);
ArrayAdapter<?> adapter1 = ArrayAdapter.createFromResource(
this, R.array.sizearray, android.R.layout.simple_spinner_item);
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
s1.setAdapter(adapter1);
edittext = (EditText) findViewById(R.id.edittext);
edittext.setOnKeyListener(new OnKeyListener() {
public boolean onKey(View v, int keyCode, KeyEvent event) {
// If the event is a key-down event on the "enter" button
if ((event.getAction() == KeyEvent.ACTION_DOWN) &&
(keyCode == KeyEvent.KEYCODE_ENTER || keyCode == KeyEvent.KEYCODE_DPAD_CENTER)) {
// Perform action on key press
int i=0;
B[i]=new store();
int n=Integer.parseInt(edittext.getText().toString());
B[i].setOrder(s.getSelectedItem().toString(), s1.getSelectedItem().toString(),n);
TextView objText=(TextView) findViewById(R.id.pl);
TextView objText1=(TextView) findViewById(R.id.pl2);
objText.setText(B[i].getPizzaName());
objText1.setText(B[i].getPizzaSize());
i++;
Toast.makeText(SpinPizza.this, edittext.getText(), Toast.LENGTH_SHORT).show();
return true;
}
return false;
}
});
Button next1 = (Button) findViewById(R.id.bill);
next1.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
Intent myIntent = new Intent(view.getContext(), Bill.class);
for(int i =0;i<B.length;i++)
{
myIntent.putExtra("myclass"+i,B[i]);
}
myIntent.putExtra("length",B.length);
startActivityForResult(myIntent, 0);
}
});
}
}
（Bill.java）
package com.Lak;
import android.app.Activity;
import android.os.Bundle;
import android.view.ViewGroup.LayoutParams;
import android.widget.TableLayout;
import android.widget.TableRow;
import android.widget.TextView;
public class Bill extends Activity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
this.setContentView(R.layout.calc);
store B[] = new store[10];
Bundle bj=getIntent().getExtras();
int length = bj.getInt("length");
for(int i = 0 ;i<length;i++)
{
B[i] = (store)bj.getParcelable("myClass"+i);
}
// B = (store[]) bj.get("myClass");
/* Find Tablelayout defined in main.xml */
TableLayout tl = (TableLayout)findViewById(R.id.myTable);
/* Create a new row to be added. */
TableRow tr = new TableRow(this);
tr.setLayoutParams(new LayoutParams(
LayoutParams.FILL_PARENT,
LayoutParams.WRAP_CONTENT));
/* Create TEXTVIEWS to be the row-content. */
for(int i=0;i<length;i++)
{ TextView b = new TextView(this);
b.setText(B[i].getPizzaName()); // NULL POINTER EXCEPTION :(
TextView b1 = new TextView(this);
b1.setText(B[i].getPizzaSize());
TextView b2 = new TextView(this);
b2.setText(B[i].getQuantity());
b.setLayoutParams(new LayoutParams(
LayoutParams.FILL_PARENT,
LayoutParams.WRAP_CONTENT));
b1.setLayoutParams(new LayoutParams(
LayoutParams.FILL_PARENT,
LayoutParams.WRAP_CONTENT));
b2.setLayoutParams(new LayoutParams(
LayoutParams.FILL_PARENT,
LayoutParams.WRAP_CONTENT));
/* Add TextViews to row. */
tr.addView(b);
tr.addView(b1);
tr.addView(b2);
/* Add row to TableLayout. */
tl.addView(tr,new TableLayout.LayoutParams(
LayoutParams.FILL_PARENT,
LayoutParams.WRAP_CONTENT));
}}
}
哪一行發生這種情況？ – Argote 2011-03-25 16:55:43
是可用的堆棧跟蹤？ – aldrin 2011-03-25 17:24:24
@Argote：這裏 - > b.setText（B [i] .getPizzaName（））; – 2011-03-25 18:41:20