这是我得到的错误。您可以在下面看到受此会话影响的所有代码。我把意图放在哪里，从哪里得到，所涉及的课程和参数。
11-30 20:37:32.870: E/AndroidRuntime(809): FATAL EXCEPTION: main
11-30 20:37:32.870: E/AndroidRuntime(809): java.lang.RuntimeException: Unable to start activity ComponentInfo{kfc.project/kfc.project.productdetail}: java.lang.NullPointerException
11-30 20:37:32.870: E/AndroidRuntime(809): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647)
11-30 20:37:32.870: E/AndroidRuntime(809): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
11-30 20:37:32.870: E/AndroidRuntime(809): at android.app.ActivityThread.access$1500(ActivityThread.java:117)
11-30 20:37:32.870: E/AndroidRuntime(809): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
11-30 20:37:32.870: E/AndroidRuntime(809): at android.os.Handler.dispatchMessage(Handler.java:99)
11-30 20:37:32.870: E/AndroidRuntime(809): at android.os.Looper.loop(Looper.java:123)
11-30 20:37:32.870: E/AndroidRuntime(809): at android.app.ActivityThread.main(ActivityThread.java:3683)
11-30 20:37:32.870: E/AndroidRuntime(809): at java.lang.reflect.Method.invokeNative(Native Method)
11-30 20:37:32.870: E/AndroidRuntime(809): at java.lang.reflect.Method.invoke(Method.java:507)
11-30 20:37:32.870: E/AndroidRuntime(809): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
11-30 20:37:32.870: E/AndroidRuntime(809): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
11-30 20:37:32.870: E/AndroidRuntime(809): at dalvik.system.NativeStart.main(Native Method)
11-30 20:37:32.870: E/AndroidRuntime(809): Caused by: java.lang.NullPointerException
11-30 20:37:32.870: E/AndroidRuntime(809): at kfc.project.productdetail.onCreate(productdetail.java:19)
11-30 20:37:32.870: E/AndroidRuntime(809): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
11-30 20:37:32.870: E/AndroidRuntime(809): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
11-30 20:37:32.870: E/AndroidRuntime(809): ... 11 more
This is the code of the java file
package kfc.project;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.widget.EditText;
import android.widget.TextView;
public class productdetail extends Activity{
@Override
protected void onCreate(Bundle bundle) {
// TODO Auto-generated method stub
super.onCreate(bundle);
setContentView(R.layout.productdetail);
Bundle extras = getIntent().getExtras();
String name = extras.getString("name");
if (name != null) {
TextView text1 = (TextView) findViewById(R.id.servingsize);
text1.setText(name);
}
/*
Intent intent = getIntent();
String str = intent.getStringExtra("name");*/
}
}
This is the code for the xml file wherein the error goes comes in when i go to this page. It isnt about cleaning the project and the manifest as well cause it works when i delete the settext code
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
android:scrollbarAlwaysDrawVerticalTrack="true"
xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="wrap_content" android:gravity="top|center"
android:background="@drawable/bg">
<TableLayout
android:id="@+id/tableLayout1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
>
<TableRow
android:id="@+id/tableRow1"
android:layout_width="wrap_content"
android:layout_height="wrap_content" >
</TableRow>
<TableRow
android:id="@+id/tableRow2"
android:layout_width="wrap_content"
android:layout_height="wrap_content" android:gravity="right">
<Button
android:id="@+id/button1"
android:background="@drawable/button2"
android:textColor="#FFFFFF"
android:layout_width="wrap_content"
android:layout_height="fill_parent"
android:text="ADD TO MENU" android:gravity="right" android:paddingRight="4sp" android:paddingTop="10sp"/>
<TableRow
android:id="@+id/tableRow3"
android:layout_width="wrap_content"
android:layout_height="wrap_content" android:gravity="left">
</TableRow>
<TableLayout
android:id="@+id/tableLayout2"
android:layout_width="match_parent"
android:layout_height="wrap_content" >
<TableRow
android:id="@+id/tableRow5"
android:layout_width="wrap_content"
android:layout_height="wrap_content" >
</TableRow>
<TableRow
android:id="@+id/tableRow6"
android:layout_width="wrap_content"
android:layout_height="wrap_content" >
<TextView
android:id="@+id/textView4"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:gravity="left"
android:text="Amount Per Serving: "
android:textAppearance="?android:attr/textAppearanceMedium" />
<TextView
android:id="@+id/textView7"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="20"
android:textAppearance="?android:attr/textAppearanceMedium" />
</TableRow>
<TableRow
android:id="@+id/tableRow7"
android:layout_width="wrap_content"
android:layout_height="wrap_content" >
<TextView
android:id="@+id/textView5"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Calories:"
android:textAppearance="?android:attr/textAppearanceMedium" />
<TextView
android:id="@+id/textView17"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="30"
android:textAppearance="?android:attr/textAppearanceMedium" />
</TableRow>
<ImageView
xmlns:android="http://schemas.android.com/apk/res/android"
android:src="@android:drawable/divider_horizontal_dark"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:scaleType="fitXY"
android:paddingLeft="5dp"
android:paddingRight="5dp"
android:paddingBottom="2dp"
android:paddingTop="2dp" />
<TableRow
android:id="@+id/tableRow8"
android:layout_width="wrap_content"
android:layout_height="wrap_content" >
<TableRow
android:id="@+id/tableRow14"
android:layout_width="wrap_content"
android:layout_height="wrap_content" >
<TextView
android:id="@+id/textView3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:gravity="right"
android:text="% Daily Value: "
android:textAppearance="?android:attr/textAppearanceMedium" />
<TextView
android:id="@+id/textView21"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="35"
android:textAppearance="?android:attr/textAppearanceMedium" />
</TableRow>
</TableRow>
</TableLayout>
<TableLayout
android:id="@+id/tableLayout3"
android:layout_width="match_parent"
android:layout_height="wrap_content" >
<TableRow
android:id="@+id/tableRow9"
android:layout_width="wrap_content"
android:layout_height="wrap_content" >
<TextView
android:id="@+id/textView8"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Total Fat:"
android:textAppearance="?android:attr/textAppearanceMedium" />
<TextView
android:id="@+id/textView22"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="60"
android:textAppearance="?android:attr/textAppearanceMedium" />
</TableRow>
<TableRow
android:id="@+id/tableRow10"
android:layout_width="wrap_content"
android:layout_height="wrap_content" >
<TextView
android:id="@+id/textView9"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text=" Saturated Fat:"
android:textAppearance="?android:attr/textAppearanceMedium" />
<TextView
android:id="@+id/textView23"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="34"
android:textAppearance="?android:attr/textAppearanceMedium" />
</TableRow>
<TableRow
android:id="@+id/tableRow11"
android:layout_width="wrap_content"
android:layout_height="wrap_content" >
<TextView
android:id="@+id/textView10"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text=" Trans Fat:"
android:textAppearance="?android:attr/textAppearanceMedium" />
<TextView
android:id="@+id/textView24"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="53"
android:textAppearance="?android:attr/textAppearanceMedium" />
</TableRow>
<TableRow
android:id="@+id/tableRow12"
android:layout_width="wrap_content"
android:layout_height="wrap_content" >
<TextView
android:id="@+id/textView11"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Cholesterol:"
android:textAppearance="?android:attr/textAppearanceMedium" />
<TextView
android:id="@+id/textView25"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="25"
android:textAppearance="?android:attr/textAppearanceMedium" />
</TableRow>
<TableRow
android:id="@+id/tableRow13"
android:layout_width="wrap_content"
android:layout_height="wrap_content" >
<TextView
android:id="@+id/textView12"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Sodium:"
android:textAppearance="?android:attr/textAppearanceMedium" />
<TextView
android:id="@+id/textView26"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="10"
android:textAppearance="?android:attr/textAppearanceMedium" />
</TableRow>
<TableRow
android:id="@+id/tableRow15"
android:layout_width="wrap_content"
android:layout_height="wrap_content" >
<TextView
android:id="@+id/textView13"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Total Carbohydrate:"
android:textAppearance="?android:attr/textAppearanceMedium" />
<TextView
android:id="@+id/textView27"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="200"
android:textAppearance="?android:attr/textAppearanceMedium" />
</TableRow>
<TableRow
android:id="@+id/tableRow16"
android:layout_width="wrap_content"
android:layout_height="wrap_content" >
<TextView
android:id="@+id/textView14"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text=" Dietary Fiber:"
android:textAppearance="?android:attr/textAppearanceMedium" />
<TextView
android:id="@+id/textView28"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="34"
android:textAppearance="?android:attr/textAppearanceMedium" />
</TableRow>
<TableRow
android:id="@+id/tableRow17"
android:layout_width="wrap_content"
android:layout_height="wrap_content" >
<TextView
android:id="@+id/textView15"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text=" Sugars:"
android:textAppearance="?android:attr/textAppearanceMedium" />
<TextView
android:id="@+id/textView29"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="16"
android:textAppearance="?android:attr/textAppearanceMedium" />
</TableRow>
<TableRow
android:id="@+id/tableRow18"
android:layout_width="wrap_content"
android:layout_height="wrap_content" >
<TextView
android:id="@+id/textView16"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Protein:"
android:textAppearance="?android:attr/textAppearanceMedium" />
<TextView
android:id="@+id/textView30"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="40"
android:textAppearance="?android:attr/textAppearanceMedium" />
</TableRow>
<ImageView
xmlns:android="http://schemas.android.com/apk/res/android"
android:src="@android:drawable/divider_horizontal_dark"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:scaleType="fitXY"
android:paddingLeft="5dp"
android:paddingRight="5dp"
android:paddingBottom="2dp"
android:paddingTop="2dp" />
<TableRow
android:id="@+id/tableRow24"
android:layout_width="wrap_content"
android:layout_height="wrap_content" >
</TableRow>
<TableRow
android:id="@+id/tableRow19"
android:layout_width="wrap_content"
android:layout_height="wrap_content" >
</TableRow>
</TableLayout>
<TableLayout
android:id="@+id/tableLayout4"
android:layout_width="match_parent"
android:layout_height="wrap_content" >
<TableRow
android:id="@+id/tableRow20"
android:layout_width="wrap_content"
android:layout_height="wrap_content" >
</TableRow>
<TableRow
android:id="@+id/tableRow21"
android:layout_width="wrap_content"
android:layout_height="wrap_content" >
</TableRow>
<TableRow
android:id="@+id/tableRow22"
android:layout_width="wrap_content"
android:layout_height="wrap_content" >
<TextView
android:id="@+id/textView19"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Vitamin A: "
android:textAppearance="?android:attr/textAppearanceMedium" />
<TextView
android:id="@+id/textView31"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="40"
android:textAppearance="?android:attr/textAppearanceMedium" />
<TextView
android:id="@+id/textView20"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text=" Vitamin C: "
android:textAppearance="?android:attr/textAppearanceMedium" />
<TextView
android:id="@+id/textView32"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="30"
android:textAppearance="?android:attr/textAppearanceMedium" />
</TableRow>
<TableRow
android:id="@+id/tableRow23"
android:layout_width="wrap_content"
android:layout_height="wrap_content" >
<TextView
android:id="@+id/textView6"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Calcium: "
android:textAppearance="?android:attr/textAppearanceMedium" />
<TextView
android:id="@+id/textView33"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="35"
android:textAppearance="?android:attr/textAppearanceMedium" />
<TextView
android:id="@+id/textView18"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text=" Iron: "
android:textAppearance="?android:attr/textAppearanceMedium" />
<TextView
android:id="@+id/textView34"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="40"
android:textAppearance="?android:attr/textAppearanceMedium" />
</TableRow>
<TableRow
android:id="@+id/tableRow25"
android:layout_width="wrap_content"
android:layout_height="wrap_content" >
</TableRow>
</TableLayout>
</LinearLayout>
这是我放额外的地方
package kfc.project;
import java.util.ArrayList;
import android.app.Activity;
import android.app.ListActivity;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
import android.widget.Toast;
public class ProductListView extends ListActivity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
final ProductList pl = new ProductList();
//setListAdapter(new ArrayAdapter<String>(this, R.layout.list_item, PRODUCTS));
setListAdapter(new ArrayAdapter<Product>(this, R.layout.list_item, pl.getList() ));
ListView lv = getListView();
lv.setTextFilterEnabled(true);
lv.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
// When clicked, show a toast with the TextView text
Toast.makeText(getApplicationContext(), "View Product", Toast.LENGTH_SHORT).show();
Product product = pl.getList().get(position);
Intent intent = new Intent(ProductListView.this, productdetail.class);
intent.putExtra("name",product.getName());
intent.putExtra("calories", product.getCalories());
intent.putExtra("serving size", product.getServingSize());
intent.putExtra("fat", product.getFat());
intent.putExtra("saturated fat", product.getSaturatedFat());
intent.putExtra("trans fat", product.getTransFat());
intent.putExtra("cholesterol", product.getCholesterol());
intent.putExtra("sodium", product.getSodium());
intent.putExtra("carbs", product.getCarbs());
intent.putExtra("protein", product.getProtein());
ProductListView.this.startActivity(intent);
startActivity(new Intent("kfc.project.PRODUCTDETAIL"));
}
});
}
//TEST STRING ARRAY
static String[] PRODUCTS = new String[] {
"Chicken", "Rice", "Coke", "Chicken Burger"
};
}
这是添加阵列列表项的位置
package kfc.project;
import java.util.ArrayList;
public class ProductList {
ArrayList<Product> list;
public ProductList (){
list = new ArrayList<Product>();
//CREATE PRODUCT HERE
Product chicken;
list.add(new Product("ChickenTest",99));
Product rice;
list.add(new Product("RiceTest",11));
}
public String[] getNames (){
int c = 0;
int size = list.size() - 1;
String[] names = new String[size];
while (size >= c) {
//names.add(list.get(c).getName());
names[c] = list.get(c).getName();
c++;
}
c = 0;
return names;
}
public ArrayList<Product> getList (){
return list;
}
}
这是参数的代码
package kfc.project;
public class Product {
String name;
int servingSize;
int calories;
int fat;
int saturatedFat;
int transFat;
int cholesterol;
int sodium;
int carbs;
int protein;
public Product (String name, int servingSize, int calories, int fat, int saturatedFat, int transFat, int cholesterol, int sodium, int carbs, int protein){
this.name=name;
this.calories=calories;
this.servingSize=servingSize;
this.fat=fat;
this.saturatedFat=saturatedFat;
this.transFat=transFat;
this.cholesterol=cholesterol;
this.sodium=sodium;
this.carbs=carbs;
this.protein=protein;
}
public Product (String name, int servingSize){
this.name=name;
this.servingSize=servingSize;
}
public String getName() {
return name;
}
public int getServingSize() {
return servingSize;
}
public int getCalories() {
return calories;
}
public int getFat() {
return fat;
}
public int getSaturatedFat() {
return saturatedFat;
}
public int getTransFat() {
return transFat;
}
public int getCholesterol() {
return cholesterol;
}
public int getSodium() {
return sodium;
}
public int getCarbs() {
return carbs;
}
public int getProtein() {
return protein;
}
}
extras变量为NULL
Bundle extras = getIntent().getExtras();
String name = extras.getString("name");
更新：
首先，这条线路不需要
startActivity(new Intent("kfc.project.PRODUCTDETAIL"));
其次，您需要从productdetail中的getIntent()中getExtra()，而不是getExtras()。样品：
// get intent object once
Intent receivedIntent = getIntent();
// get product name
String productName = receivedIntent.getExtra("name");
// get serving size
int servingSize = receivedIntent.getExtra("serving size");
// do the same for other props
Bundle extras = getIntent().getExtras();
String name = extras.getString("name");
如果intent中没有存储额外内容，getExtras((可能返回null。检查附加项是否为null。
您可能需要对额外内容进行null检查。
只需删除这行
startActivity(new Intent("kfc.project.PRODUCTDETAIL"));
它在没有额外内容的情况下启动您的活动，导致您的额外内容为空