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家伙,我想创建Android上点击列表视图,但我不断收到此错误显示java.lang.NullPointerException:在一个ListView
显示java.lang.NullPointerException:试图调用虚拟方法无效android.widget .ListView.setAdapter(android.widget.ListAdapter)'在一个空对象引用
我不确定这是什么意思我很新的Android开发 你能帮我吗?...谢谢你Advance
My ** CitySelection.java **文件
package com.sourcey.materiallogindemo;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
public class CitySelection extends AppCompatActivity {
ListView listView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_city_selection);
listView = (ListView)findViewById(android.R.id.list);
String[] values = new String[] {"Chennai" , "Madurai" , "Delhi" , "Trichy"};
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.activity_list_item, android.R.id.text1, values);
listView.setAdapter(adapter);
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
if(position==0){
Intent myintent = new Intent(view.getContext() , MaduraiCityMain.class);
startActivityForResult(myintent,0);
}
if(position==1){
Intent myintent = new Intent(view.getContext() , ChennaiCityMain.class);
startActivityForResult(myintent,1);
}
}
});
}
}
'的ListView =(ListView中)findViewById(android.R.id.list);'应'的ListView =(ListView中)findViewById(R.id.list);' – rafsanahmad007