java向自定义listView动态添加行(每行有多个字符串)
我的上一个应用程序有一个自定义布局,listview
,我可以添加项目,这些项目将出现在listview
中。
现在,我想制作一个应用程序,也有自定义布局,listview
,但是每一行都有3个不同的字符串,所以在我的应用程序生成一个新行之前,你必须输入3个不同的字符串,然后他会生成一个新行。但这不起作用。。。你能告诉我哪里出了错吗?已经谢谢你了
主要活动
ListView ListView ;
EditText editTextMerk ;
EditText editTextBeschrijving ;
EditText editTextKm ;
Button voegToe ;
ArrayList<String> merk;
ArrayList<String> beschrijving ;
ArrayList<String> km ;
CustomAdapter adapter ;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
editTextMerk = (EditText) findViewById(R.id.editTextMerk) ;
editTextBeschrijving = (EditText) findViewById(R.id.editTextBeschrijving) ;
editTextKm = (EditText) findViewById(R.id.editTextKm) ;
ListView =(ListView) findViewById(R.id.Listview) ;
adapter = new CustomAdapter(this , merk , beschrijving , km ) ;
ListView.setAdapter(adapter);
voegToe.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
merk.add(editTextMerk.getText().toString()) ;
beschrijving.add(editTextBeschrijving.getText().toString()) ;
km.add(editTextKm.getText().toString()) ;
adapter.notifyDataSetChanged();
}
});
}
这是我的CustomAdapter类
LayoutInflater mInflater ;
ArrayList<String> merk;
ArrayList<String> beschrijving ;
ArrayList<String> km ;
public CustomAdapter(Context c, ArrayList<String> merk, ArrayList<String> beschrijving, ArrayList<String> km) {
this.merk = merk;
this.beschrijving = beschrijving;
this.km = km;
mInflater = (LayoutInflater) c.getSystemService(Context.LAYOUT_INFLATER_SERVICE) ;
}
@Override
public int getCount() {
return merk.size();
}
@Override
public Object getItem(int position) {
return merk.get(position);
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View v = mInflater.inflate(R.layout.layout_row, null) ;
TextView brand = (TextView) v.findViewById(R.id.textViewMerk) ;
TextView discription = (TextView) v.findViewById(R.id.textViewBeschrijving) ;
TextView distance = (TextView) v.findViewById(R.id.textViewKm) ;
brand.setText(merk.get(position));
discription.setText(beschrijving.get(position));
distance.setText(km.get(position));
return v;
}
# 1 楼答案
有两个问题:
onCreate()
方法中找不到voegToe
。尝试对空对象调用setOnClickListener()
会产生NPE李>setAdapter()
调用到ListView时,getCount()
调用时,当它们为null时传递它们将产生NPE李>因此,您需要按如下方式更新活动: