当我们单击列表视图项时如何启动新活动

Question

I am trying to start an activity,when I click on listview item.But when I run the program,I am getting some error like:

Error:(45, 43) error: no suitable constructor found for Intent(,Class) constructor Intent.Intent(String,Uri) is not applicable (argument mismatch; cannot be converted to String) constructor Intent.Intent(Context,Class) is not applicable (argument mismatch; cannot be converted to Context) Error:(51, 44) error: no suitable constructor found for Intent(,Class) constructor Intent.Intent(String,Uri) is not applicable (argument mismatch; cannot be converted to String) constructor Intent.Intent(Context,Class) is not applicable (argument mismatch; cannot be converted to Context) Error:(57, 43) error: no suitable constructor found for Intent(,Class) constructor Intent.Intent(String,Uri) is not applicable (argument mismatch; cannot be converted to String) constructor Intent.Intent(Context,Class) is not applicable (argument mismatch; cannot be converted to Context) Note: Some messages have been simplified; recompile with -Xdiags:verbose to get full output Error:Execution failed for task ':app:compileDebugJavaWithJavac'.

Compilation failed; see the compiler error output for details.

Menu.java public class Menu extends AppCompatActivity {

    ListView lv;

    private static String[] menu_list = { "list one", "list 2", "list 3" };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_menu);
        listview();
    }

    public void listview() {
        lv = (ListView) findViewById(R.id.lv_Menu_List);
        ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,
                R.layout.list_layout, menu_list);
        lv.setAdapter(adapter);
        lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view,
                    int position, long id) {

                // String value =(String)lv.getItemAtPosition(position);

                if (position == 0) {
                    Intent intent = new Intent(this, ListOne.class);
                    startActivity(intent);
                } else if (position == 1) {
                    Intent intent = new Intent(this, List2.class);
                    startActivity(intent);
                } else if (position == 2) {
                    Intent intent = new Intent(this, List3.class);
                    startActivity(intent);
                }

            }
        });
    }
}

activity_menu.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.examplemenu.Menu">

    <ListView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/lv_Menu_List"
        android:layout_centerHorizontal="true"
        android:layout_alignParentTop="true" />
</RelativeLayout>

list_layout.xml

    <xml version="1.0" encoding="utf-8"?>
    <TextView xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:paddingBottom="@dimen/activity_vertical_margin"
        android:paddingLeft="@dimen/activity_horizontal_margin"
        android:paddingRight="@dimen/activity_horizontal_margin"
        android:paddingTop="@dimen/activity_vertical_margin"
        android:soundEffectsEnabled="true">
</TextView>

Answer 1

Try this:

 Intent intent=new Intent(Menu.this,ListOne.class);
 startActivity(intent);

Because just this refers to AdapterView.OnItemClickListener not Menu class.

Answer 2

You can use Menu.this or getApplicationContext() (both works), hope it helps!

public void listview()
    {
        lv=(ListView)findViewById(R.id.lv_Menu_List);
        ArrayAdapter<String> adapter=new ArrayAdapter<String>(this,R.layout.list_layout,menu_list);
        lv.setAdapter(adapter);
        lv.setOnItemClickListener(
                new AdapterView.OnItemClickListener() {
                    @Override
                    public void onItemClick(AdapterView<?> parent, View view, int position, long id) {

                    //String value =(String)lv.getItemAtPosition(position);

                    if(position==0){
                        Intent intent=new Intent(getApplicationContext(),ListOne.class);
                        startActivity(intent);
                     }
                    else {
                        if (position == 1) {
                            Intent intent = new Intent(Menu.this, List2.class);
                            startActivity(intent);

                        } else if (position == 2) {
                            Intent intent = new Intent(Menu.this, List3.class);
                            startActivity(intent);
                        }
                    }
                }
            });
}

Answer 3

You can use getApplicationContext() and also switch conditions:

public void listview() {
    lv = (ListView) findViewById(R.id.lv_Menu_List);
    ArrayAdapter<String> adapter = new ArrayAdapter<String> (
        this,
        R.layout.list_layout,
        menu_list);
    lv.setAdapter(adapter);
    lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view,
                int position, long id) {
                final Intent intent;
                switch (position) {
                    case 0:
                        intent = new Intent(getApplicationContext, listone.class);
                        break;

                    case 1:
                        intent = new Intent(getApplicationContext, list2.class);
                        break;
                    case 2:
                        intent = new Intent(getApplicationContext, list3.class);
                        break;

                    default:
                        intent = new Intent(getApplicationContext, YourDefaultActivity.class);
                        break;
                }
                context.startActivity(intent);
            }
        }
    });
}