java - 新 Intent 创建强制关闭

Question

我将我的应用分为 3 个类。用户可以在其中选择要使用的功能的主类。 map 功能工作正常，但当用户单击按钮时我的方向功能不起作用导致强制关闭，我认为这与布局有关。

主类文件

package com.sammy.umass;

import android.app.Activity;
import android.net.Uri;
import android.os.Bundle;
import android.view.View;
import android.content.Intent;
import android.widget.Button;



public class UMassGuide extends Activity {
/** Called when the activity is first created. */



//buttons
private Button goHereButton;
private Button mapButton;
private Button spireButton;
private Button sparkButton;
private Button websiteButton;

@Override
public void onCreate(Bundle savedInstanceState) 
{
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    goHereButton  = (Button) findViewById(R.id.button1);
    goHereButton.setOnClickListener(new View.OnClickListener() 
    {
       public void onClick(View arg0) 
       {
       Intent i = new Intent(UMassGuide.this, DirectionsScreenActivity.class);
       startActivity(i);
       }
    });

    mapButton  = (Button) findViewById(R.id.button2);
    mapButton.setOnClickListener(new View.OnClickListener() 
    {
       public void onClick(View arg0) 
       {
       Intent i = new Intent(UMassGuide.this, UmassMap.class);
       startActivity(i);
       }
    });

    spireButton  = (Button) findViewById(R.id.button3);
    spireButton.setOnClickListener(new View.OnClickListener() 
    {
        public void onClick(View arg0) 
        {
            Uri uri = Uri.parse("https://spire.umass.edu/psp/heproda/EMPLOYEE/HRMS/?cmd=login&languageCd=ENG&"); 
            Intent intent = new Intent(Intent.ACTION_VIEW, uri); startActivity(intent);
        }
     });

    sparkButton  = (Button) findViewById(R.id.button4);
    sparkButton.setOnClickListener(new View.OnClickListener() 
    {
        public void onClick(View arg0) 
        {
            Uri uri = Uri.parse("https://spark.oit.umass.edu/webct/logonDisplay.dowebct"); 
            Intent intent = new Intent(Intent.ACTION_VIEW, uri); startActivity(intent);
        }
     });

    websiteButton  = (Button) findViewById(R.id.button5);
    websiteButton.setOnClickListener(new View.OnClickListener() 
    {
        public void onClick(View arg0) 
        {
            Uri uri = Uri.parse("http://www.umass.edu/"); 
            Intent intent = new Intent(Intent.ACTION_VIEW, uri); startActivity(intent);
        }
     });




}
}

方向文件(打开此类时发生强制关闭)

package com.sammy.umass;

import android.app.ExpandableListActivity;
import android.os.Bundle;
import android.view.ContextMenu;
import android.view.Gravity;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.view.ContextMenu.ContextMenuInfo;
import android.widget.AbsListView;
import android.widget.BaseExpandableListAdapter;
import android.widget.ExpandableListAdapter;
import android.widget.ExpandableListView;
import android.widget.TextView;
import android.widget.Toast;
import android.widget.ExpandableListView.ExpandableListContextMenuInfo;


public class DirectionsScreenActivity extends ExpandableListActivity {
ExpandableListAdapter mAdapter;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    // Set up our adapter
    mAdapter = new MyExpandableListAdapter();
    setListAdapter(mAdapter);
    registerForContextMenu(getExpandableListView());
}

@Override
public void onCreateContextMenu(ContextMenu menu, View v, ContextMenuInfo menuInfo) {
    menu.setHeaderTitle("Sample menu");
    menu.add(0, 0, 0, R.string.expandable_list_sample_action);
}

@Override
public boolean onContextItemSelected(MenuItem item) {
    ExpandableListContextMenuInfo info = (ExpandableListContextMenuInfo) item.getMenuInfo();

    String title = ((TextView) info.targetView).getText().toString();

    int type = ExpandableListView.getPackedPositionType(info.packedPosition);
    if (type == ExpandableListView.PACKED_POSITION_TYPE_CHILD) {
        int groupPos = ExpandableListView.getPackedPositionGroup(info.packedPosition); 
        int childPos = ExpandableListView.getPackedPositionChild(info.packedPosition); 
        Toast.makeText(this, title + ": Child " + childPos + " clicked in group " + groupPos,
                Toast.LENGTH_SHORT).show();
        return true;
    } else if (type == ExpandableListView.PACKED_POSITION_TYPE_GROUP) {
        int groupPos = ExpandableListView.getPackedPositionGroup(info.packedPosition); 
        Toast.makeText(this, title + ": Group " + groupPos + " clicked", Toast.LENGTH_SHORT).show();
        return true;
    }

    return false;
}

/**
 * A simple adapter which maintains an ArrayList of photo resource Ids. 
 * Each photo is displayed as an image. This adapter supports clearing the
 * list of photos and adding a new photo.
 *
 */
public class MyExpandableListAdapter extends BaseExpandableListAdapter {
    // Sample data set.  children[i] contains the children (String[]) for groups[i].
    private String[] groups = { "   Academic Buildings", "   Residential Buildings", "   Dining Commons", "   All Buildings A-Z" };
    private String[][] children = {
            { "Agricultural Engineering Bldg", "Army ROTC Bldg", "Arnold House", "(Studio) Arts Building" },
            { "Baker Hall", "Brett Hall", "Brooks Hall", "Brown Hall" },
            { "Berkshire", "Franklin","Hampden","Hampshire","Worcester" },
            { "Agricultural Engineering Bldg", "Army ROTC Bldg", "Arnold House", "(Studio) Arts Building" }
    };

    public Object getChild(int groupPosition, int childPosition) {
        return children[groupPosition][childPosition];
    }

    public long getChildId(int groupPosition, int childPosition) {
        return childPosition;
    }

    public int getChildrenCount(int groupPosition) {
        return children[groupPosition].length;
    }

    public TextView getGenericView() {
        // Layout parameters for the ExpandableListView
        AbsListView.LayoutParams lp = new AbsListView.LayoutParams(
                ViewGroup.LayoutParams.MATCH_PARENT, 64);

        TextView textView = new TextView(DirectionsScreenActivity.this);
        textView.setLayoutParams(lp);
        // Center the text vertically
        textView.setGravity(Gravity.CENTER_VERTICAL | Gravity.LEFT);
        // Set the text starting position
        textView.setPadding(36, 0, 0, 0);
        return textView;
    }

    public View getChildView(int groupPosition, int childPosition, boolean isLastChild,
            View convertView, ViewGroup parent) {
        TextView textView = getGenericView();
        textView.setText(getChild(groupPosition, childPosition).toString());
        return textView;
    }

    public Object getGroup(int groupPosition) {
        return groups[groupPosition];
    }

    public int getGroupCount() {
        return groups.length;
    }

    public long getGroupId(int groupPosition) {
        return groupPosition;
    }

    public View getGroupView(int groupPosition, boolean isExpanded, View convertView,
            ViewGroup parent) {
        TextView textView = getGenericView();
        textView.setText(getGroup(groupPosition).toString());
        return textView;
    }

    public boolean isChildSelectable(int groupPosition, int childPosition) {
        return true;
    }

    public boolean hasStableIds() {
        return true;
    }

}
}

Answer 1

您是否已将 DirectionScreenActivity 添加到您的 list 文件中？否则，可能会导致致命的崩溃。