我在listview中根据他们从一个活动到另一个活动的点击传递参数它在传递参数行的log cat中显示错误 firs activity.java
public class SouthIndianvegrecipes1 extends Activity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
ArrayList<Recipedetails> image_details = GetSearchResults();
final ListView lv1 = (ListView) findViewById(R.id.listV_main);
lv1.setAdapter(new ItemListBaseAdapter(this, image_details));
lv1.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> a, View v, int position, long id) {
Object o = lv1.getItemAtPosition(position);
Recipedetails obj_itemDetails = (Recipedetails)o;
Toast.makeText(SouthIndianvegrecipes1.this, "You have chosen : " + " " + obj_itemDetails.getName(), Toast.LENGTH_LONG).show();
Intent newActivity = new Intent(SouthIndianvegrecipes1.this,
SouthIndianvegmanualrecipes.class );
newActivity.putExtra("name", obj_itemDetails.getName());
startActivity(newActivity);
}
});
}
private ArrayList<Recipedetails> GetSearchResults(){
ArrayList<Recipedetails> results = new ArrayList<Recipedetails>();
Recipedetails item_details = new Recipedetails();
item_details.setName("Godhumai veg adai");
item_details.setItemDescription("This is very good for dibets people");
//item_details.setUrlWiki("https://www.youtube.com/watch?v=C_r0mFvMSfU");
item_details.setImageNumber(12);
results.add(item_details);
item_details = new Recipedetails();
item_details.setName("Soyamore koozh");
item_details.setItemDescription("Tasty to have this as main dish");
//item_details.setUrlWiki("https://www.youtube.com/watch?v=C_r0mFvMSfU");
item_details.setImageNumber(13);
results.add(item_details);
item_details = new Recipedetails();
item_details.setName("Tomato kulambu");
item_details.setItemDescription("Good side dish for rice and dinner");
//item_details.setUrlWiki("https://www.youtube.com/watch?v=C_r0mFvMSfU");
item_details.setImageNumber(14);
results.add(item_details);
item_details = new Recipedetails();
item_details.setName("Tomato upma");
item_details.setItemDescription("Evening time dinner for kids");
//item_details.setUrlWiki("https://www.youtube.com/watch?v=C_r0mFvMSfU");
item_details.setImageNumber(15);
results.add(item_details);
item_details = new Recipedetails();
item_details.setName("Navratri special vada");
item_details.setItemDescription("Good snacks at the function");
//item_details.setUrlWiki("https://www.youtube.com/watch?v=C_r0mFvMSfU");
item_details.setImageNumber(16);
results.add(item_details);
item_details = new Recipedetails();
item_details.setName("Egg kurma");
item_details.setItemDescription("Wonderful dish made by egg");
//item_details.setUrlWiki("https://www.youtube.com/watch?v=C_r0mFvMSfU");
item_details.setImageNumber(17);
results.add(item_details);
item_details = new Recipedetails();
item_details.setName("Milagu kuzhambu");
item_details.setItemDescription("Good for digestion purpose");
//item_details.setUrlWiki("https://www.youtube.com/watch?v=C_r0mFvMSfU");
item_details.setImageNumber(18);
results.add(item_details);
item_details = new Recipedetails();
item_details.setName("Rasam");
item_details.setItemDescription("Last and famous dish in lunch,good for health also");
//item_details.setUrlWiki("https://www.youtube.com/watch?v=C_r0mFvMSfU");
item_details.setImageNumber(19);
results.add(item_details);
item_details = new Recipedetails();
item_details.setName("Vegetable kootu");
item_details.setItemDescription("Nice and healthy one");
//item_details.setUrlWiki("https://www.youtube.com/watch?v=C_r0mFvMSfU");
item_details.setImageNumber(20);
results.add(item_details);
item_details = new Recipedetails();
item_details.setName("Avial");
item_details.setItemDescription("Easy to prepare and lots of vegetable");
//item_details.setUrlWiki("https://www.youtube.com/watch?v=C_r0mFvMSfU");
item_details.setImageNumber(21);
results.add(item_details);
item_details = new Recipedetails();
item_details.setName("kothavarangaicurry");
item_details.setItemDescription("Tamilnadu special and healthy too");
//item_details.setUrlWiki("https://www.youtube.com/watch?v=C_r0mFvMSfU");
item_details.setImageNumber(22);
results.add(item_details);
return results;
}
}
passing the arguments after toasting ,passing their names
second activity.java
public class SouthIndianvegmanualrecipes extends Activity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.recipe_manual);
}
String value =null;
Bundle extras = getIntent().getExtras();
{
if (extras != null) {
if (extras.containsKey("name")) {
value = extras.getString("name");
}
}
{
//int obj_itemDetails.getImageNumber() = extras.getIntArray("numbers");
//private ArrayList<Recipedetails2> GetSearchResults(){
//ArrayList<Recipedetails2> results = new ArrayList<Recipedetails2>();
if(value.equals("Godhumai veg adai"))
{
Recipedetails2 item_details = new Recipedetails2();
item_details.setName("Godhumai veg adai");
item_details.setIngredients("This is very good for dibets people");
item_details.setMethods("This is very good for dibets people");
}
else if(value.equals("Soyamore koozh"))
{
Recipedetails2 item_detail1 = new Recipedetails2();
item_detail1.setName("Soyamore koozh");
item_detail1.setIngredients("Tasty to have this as main dish");
item_detail1.setMethods("This is very good for dibets people");
}
else if(value.equals("Tomato kulambu"))
{
Recipedetails2 item_detail3 = new Recipedetails2();
item_detail3.setName("Tomato kulambu");
item_detail3.setIngredients("Good side dish for rice and dinner");
item_detail3.setMethods("This is very good for dibets people");
}
else if(value.equals("Navratri special vada"))
{
Recipedetails2 item_detail5 = new Recipedetails2();
item_detail5.setName("Navratri special vada");
item_detail5.setIngredients("Good snacks at the function");
item_detail5.setMethods("This is very good for dibets people");
}
else if(value.equals("Egg kurma"))
{
Recipedetails2 item_detail6 = new Recipedetails2();
item_detail6.setName("Egg kurma");
item_detail6.setIngredients("Wonderful dish made by egg");
item_detail6.setMethods("This is very good for dibets people");
}
else if(value.equals("Milagu kuzhambu"))
{
Recipedetails2 item_detail7 = new Recipedetails2();
item_detail7.setName("Milagu kuzhambu");
item_detail7.setIngredients("Good for digestion purpose");
item_detail7.setMethods("This is very good for dibets people");
}
else if(value.equals("Rasam"))
{
Recipedetails2 item_detail8 = new Recipedetails2();
item_detail8.setName("Rasam");
item_detail8.setIngredients("Last and famous dish in lunch,good for health also");
item_detail8.setMethods("This is very good for dibets people");
}
else if(value.equals("Vegetable kootu"))
{
Recipedetails2 item_detail9 = new Recipedetails2();
item_detail9.setName("Vegetable kootu");
item_detail9.setIngredients("Nice and healthy one");
item_detail9.setMethods("This is very good for dibets people");
}
else if(value.equals("Avial"))
{
Recipedetails2 item_detail10 = new Recipedetails2();
item_detail10.setName("Avial");
item_detail10.setIngredients("Easy to prepare and lots of vegetable");
item_detail10.setMethods("This is very good for dibets people");
}
else
{
Recipedetails2 item_detail11 = new Recipedetails2();
item_detail11.setName("kothavarangaicurry");
item_detail11.setIngredients("Tamilnadu special and healthy too");
item_detail11.setMethods("This is very good for dibets people");
}
}
}
在此行中显示错误String value = getIntent（）。getStringExtra（“name”）; 我的日志cat错误是
03-08 04:52:09.754: E/AndroidRuntime(1048): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.recipestutors/com.example.recipestutors.SouthIndianvegmanualrecipes}: java.lang.NullPointerException
03-08 04:52:09.754: E/AndroidRuntime(1048): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2106)
03-08 04:52:09.754: E/AndroidRuntime(1048): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
03-08 04:52:09.754: E/AndroidRuntime(1048): at android.app.ActivityThread.access$600(ActivityThread.java:141)
03-08 04:52:09.754: E/AndroidRuntime(1048): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
03-08 04:52:09.754: E/AndroidRuntime(1048): at android.os.Handler.dispatchMessage(Handler.java:99)
03-08 04:52:09.754: E/AndroidRuntime(1048): at android.os.Looper.loop(Looper.java:137)
03-08 04:52:09.754: E/AndroidRuntime(1048): at android.app.ActivityThread.main(ActivityThread.java:5039)
03-08 04:52:09.754: E/AndroidRuntime(1048): at java.lang.reflect.Method.invokeNative(Native Method)
03-08 04:52:09.754: E/AndroidRuntime(1048): at java.lang.reflect.Method.invoke(Method.java:511)
03-08 04:52:09.754: E/AndroidRuntime(1048): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
03-08 04:52:09.754: E/AndroidRuntime(1048): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
03-08 04:52:09.754: E/AndroidRuntime(1048): at dalvik.system.NativeStart.main(Native Method)
03-08 04:52:09.754: E/AndroidRuntime(1048): Caused by: java.lang.NullPointerException
03-08 04:52:09.754: E/AndroidRuntime(1048): at com.example.recipestutors.SouthIndianvegmanualrecipes.<init>(SouthIndianvegmanualrecipes.java:79)
03-08 04:52:09.754: E/AndroidRuntime(1048): at java.lang.Class.newInstanceImpl(Native Method)
03-08 04:52:09.754: E/AndroidRuntime(1048): at java.lang.Class.newInstance(Class.java:1319)
03-08 04:52:09.754: E/AndroidRuntime(1048): at android.app.Instrumentation.newActivity(Instrumentation.java:1054)
03-08 04:52:09.754: E/AndroidRuntime(1048): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2097)
03-08 04:52:09.754: E/AndroidRuntime(1048): ... 11 more
答案 0 :(得分：0)
在尝试获取您正在寻找的值之前，请不要直接调用意图尝试执行以下操作来检查一切是否正确
String value =null;
Bundle extras = getIntent().getExtras();
if (extras != null) {
if (extras.containsKey("name")) {
value = extras.getString("name");
}
}
尝试在目标类中定义公共静态String（SouthIndianvegmanualrecipes）。例如。：
public static String PRODUCT_NAME = "PRODUCT NAME PLACEHOLDER";
然后在你的第一堂课做
newActivity.putExtra(SouthIndianvegmanualrecipes.PRODUCT_NAME, obj_itemDetails.getName());
在目标班级
Bundle extras = getIntent().getExtras();
if (extras != null) {
if (extras.containsKey(PRODUCT_NAME)) {
value = extras.getString(PRODUCT_NAME);
}
}
答案 1 :(得分：0)
我猜private Object getIntent;是罪魁祸首。尝试从代码下面删除它。
public class SouthIndianvegmanualrecipes extends Activity {
private Object getIntent;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.recipe_manual);
String value =getIntent().getStringExtra("name");
答案 2 :(得分：0)
在第二项活动中，我们必须像这样运作
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.recipe_manual);
Intent intent = getIntent();
String value = intent.getStringExtra("name");
答案 3 :(得分：0)
请参阅此链接以获取答案http://stackoverflow.com/questions/15289809/how-to-pass-the-string-and-get-their-data-after-clicking-the-item-in-an-listview这是适合我的正确代码