Question

我在程序中做了以下事情：

我在Buttons课程中以编程方式生成了一些MenuItemsActivity。我在Listview课程的xml中有一个MenuItemsActivity。
当我点击按钮时，Listview中会加载相应的内容。我只是刷新活动，即我使用相同的Listview根据点击的按钮加载不同的内容。

我想做以下事情：

单击按钮时，我想将按钮的背景更改为＆＃39; blue_tab`，并在重新加载相同的活动时保持相同的颜色。任何人都可以指导我一步一步做什么，因为我是Android的新手。

  i = getIntent();
String Salad=i.getStringExtra("Salad");
String cat_name_from_fragment=i.getStringExtra("category name");
final ListView salad_list = (ListView) findViewById(R.id.salads);

category = new ArrayList<HashMap<String, String>>();
items = new ArrayList<HashMap<String, String>>();
db = new DbHelper(MenuItemsActivity.this);
category.clear();
if (i.getStringExtra("category name") != null) {
    String getcategory = i.getStringExtra("category name").toString();
    items = db.retrieve_item_details(getcategory);
    Log.i("sub items", "" + items);
}
else if(cat_name_from_fragment!=null)
{
    items = db.retrieve_item_details(cat_name_from_fragment);   
}
else
{
    items = db.retrieve_item_details("Salads");
}
category = db.retrieve_category_name();


count = category.size();
Log.i("Sqlite database values", "" + count + " " + category);
if (android.os.Build.VERSION.SDK_INT > 9) {
    StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder()
            .permitAll().build();

    StrictMode.setThreadPolicy(policy);
}

LinearLayout l1 = (LinearLayout) findViewById(R.id.tableRow1);
int i = 0;
for (HashMap<String, String> map : category)

    for (Entry<String, String> mapEntry : map.entrySet()) {

        String key = mapEntry.getKey();
        String value = mapEntry.getValue();
        TextView tv2 = new TextView(this);
        tv2.setLayoutParams(new LinearLayout.LayoutParams(40, 90));
        Log.i("map", "" + value);
        final Button tv1 = new Button(this);
        tv1.setId(i);
        tv1.setText(value);
        tv1.setTextSize(35);

        tv1.setTextColor(Color.parseColor("#1569C7"));
        tv1.setGravity(Gravity.CENTER);
        tv1.setBackgroundDrawable(getResources().getDrawable(R.drawable.popup));
        tv1.setLayoutParams(new LinearLayout.LayoutParams(300,90));
        tv1.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                String text = tv1.getText().toString();
                Log.e("text message", "" + text);
                tv1.setBackgroundDrawable(getResources().getDrawable(R.drawable.blue_tab));
                Toast.makeText(MenuItemsActivity.this, "clicked", 1000)
                        .show();
                Intent i = new Intent(MenuItemsActivity.this,
                        MenuItemsActivity.class);
                i.putExtra("category name", "" + text);
                finish();
                startActivity(i);
            }
        });
        /*TextView tv2 = new TextView(this);

        tv2.setText("      ");
        tv2.setTextSize(10);

        tv2.setGravity(Gravity.CENTER);*/
        l1.addView(tv1);
        l1.addView(tv2);

        i++;
        Log.e("i count ", "" + i);
    }
final int imageArra[] = { R.drawable.leftbar_logo ,R.drawable.leftbar_logo};


ListAdapter k = new SimpleAdapter(MenuItemsActivity.this, items,
        R.layout.menulist, new String[] { "Item_Name", "Desc",
                "Currency", "Price","url","veggie","cat" }, new int[] { R.id.cat_name,
                R.id.textView1, R.id.textView2, R.id.textView3,R.id.url,R.id.veggie,R.id.Category}) {

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        // TODO Auto-generated method stub
        final View v = super.getView(position, convertView, parent);

        final ImageView im=(ImageView)v.findViewById(R.id.imageView1);
        TextView url=(TextView)v.findViewById(R.id.url);

        TextView veg=(TextView)v.findViewById(R.id.veggie);
        String vegg=veg.getText().toString();

        ImageView imagevegs=(ImageView)v.findViewById(R.id.veggies);
        Log.i("veggie",""+vegg);
        if(vegg.compareToIgnoreCase("Veg")==0)
        {


            imagevegs.setImageResource(R.drawable.veg);
            imagevegs.setScaleType(ImageView.ScaleType.CENTER_INSIDE);
        }
        else
        {imagevegs.setScaleType(ImageView.ScaleType.CENTER_INSIDE);
            imagevegs.setImageResource(R.drawable.non);
        }

        final String urls="http://166.62.17.208/"+url.getText().toString();
        Log.i("urls",""+urls);

        imageLoader.DisplayImage(urls,im);
        //return super.getView(position, convertView, parent);
        return v;
    }

};
salad_list.setAdapter(k);

Answer 1

您可以使用PreferenceManager保存数据，并在重新加载/重新启动应用时使用它

<强>样品：

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            String text = tv1.getText().toString();
            Log.e("text message", "" + text);
            if(PreferenceManager.getDefaultSharedPreferences(MenuItemsActivity.this).getString("button", "").length != 0)
                tv1.setBackgroundDrawable(getResources().getDrawable(R.drawable.blue_tab));
            else
            {
                Editor editor = PreferenceManager.getDefaultSharedPreferences(MenuItemsActivity.this).edit();
                editor.putString("button", "1");
                editor.commit(); 
                tv1.setBackgroundDrawable(getResources().getDrawable(R.drawable.blue_tab)); 
            }
            Toast.makeText(MenuItemsActivity.this, "clicked", 1000)
                    .show();
            Intent i = new Intent(MenuItemsActivity.this,
                    MenuItemsActivity.class);
            i.putExtra("category name", "" + text);
            finish();
            startActivity(i);
        }

尝试在当前位置设置标记会给我nullpointer异常

1 个答案: