无法通过活动更新列表视图 [英] Cannot update listview through activity

问题描述

我创建了一个基于列表视图的应用程序，当我通过另一个活动添加数据时，数据不会在列表视图中更新，因为它应该在列表视图中更新!!



当我在活动中的保存按钮上创建了一个onSave方法但它似乎没有在lsit视图中更新。



mainactivity .java

i have created an listview based app in which when i add data through another activity the data doesnt get updated in the listview where as it should get updated in the listview !!

when i have created an onSave method on the save button in the activity but it doesnt seem to get updated in the lsit view.

mainactivity.java

package com.example.listviewdemo;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.widget.ListView;

public class MainActivity extends Activity {
    TimeTrackerAdapter timeTrackerAdapter;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ListView listView = (ListView)
                findViewById(R.id.times_list);
                timeTrackerAdapter = new TimeTrackerAdapter();
                listView.setAdapter(timeTrackerAdapter);
    }

    public boolean onCreateOptionsMenu(Menu m) {
        super.onCreateOptionsMenu(m);
        MenuInflater menuInflater = getMenuInflater();
        menuInflater.inflate(R.menu.time_list_menu, m );
        return true;
    }

    public static final int TIME_ENTRY_REQUEST_CODE = 1;
    public boolean onMenuItemSelected(int featureId, MenuItem item) {
        if (item.getItemId() == R.id.add_time_menu_item) {
            Intent intent = new Intent(this, AddTimeActivity.class);
            startActivityForResult(intent, TIME_ENTRY_REQUEST_CODE);
            return true;
        }
        return super.onOptionsItemSelected(item);
    }


    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (requestCode == TIME_ENTRY_REQUEST_CODE) {
            if (resultCode == RESULT_OK) {
                String notes = data.getStringExtra("notes");
                String time = data.getStringExtra("time");

                timeTrackerAdapter.addTimeRecord( new TimeRecord(time, notes));
                timeTrackerAdapter.notifyDataSetChanged();
            }
            }
    }



}

addtimeactivity.java

addtimeactivity.java

package com.example.listviewdemo;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;

public class AddTimeActivity extends Activity {

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.add_time);
        }
    public void onCancel(View view) {
        finish();
    }
    public void onSave(View view) {
        Intent intent = getIntent();

        EditText timeView = (EditText)findViewById(R.id.time_view);
        intent.putExtra("time", timeView.getText().toString());

        EditText notesView = (EditText)findViewById(R.id.notes_view);
        intent.putExtra("notes", notesView.getText().toString());

        this.setResult(RESULT_OK, intent);
        finish();
    }
}

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