2020-09-21
有大佬帮我看一下有什么问题吗。。。运行不出来这个界面，显示app停止运行
package com.example.hp.myapplication;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.AutoCompleteTextView;import android.widget.ListView;import android.widget.ProgressBar;import android.widget.SeekBar;import android.widget.Spinner;import android.widget.Toast;import java.util.ArrayList;import java.util.List;public class CountActivity extends AppCompatActivity { ProgressBar pb; SeekBar seek; AutoCompleteTextView act; Spinner sp; ListView lv; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); pb=findViewById(R.id.progressBar3); seek=findViewById(R.id.seekBar); act=findViewById(R.id.autoCompleteTextView2); sp=findViewById(R.id.spinner2); lv =findViewById(R.id.listview2); //往该控件中添加可以自动补齐的字符 //字符放在集合中 List list=new ArrayList(); list.add(“china”); list.add(“blue”); list.add(“tianjin”); list.add(“aa”); list.add(“aaa”); list.add(“aaab”); //绑定需要适配器 ArrayAdapter adapter=new ArrayAdapter(CountActivity.this,android.R.layout.simple_dropdown_item_1line,list); //绑定适配器 act.setAdapter(adapter); ArrayAdapter adapter1=new ArrayAdapter(CountActivity.this,android.R.layout.select_dialog_multichoice,list); sp.setAdapter(adapter1); lv.setAdapter(adapter); lv.setOnItemClickListener(new AdapterView.OnItemClickListener() { @Override public void onItemClick(AdapterView<?> parent, View view, int position, long id) { // String item1= lv.getSelectedItem().toString(); String item2=lv.getItemAtPosition(position).toString(); Toast.makeText(CountActivity.this ,"—", Toast.LENGTH_SHORT).show(); } }); //seekBar的监听事件 seek.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() { @Override public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) { Toast.makeText(CountActivity.this,“当前进度为:”+progress,Toast.LENGTH_LONG).show(); } @Override public void onStartTrackingTouch(SeekBar seekBar) { Toast.makeText(CountActivity.this,“开始点击了！”,Toast.LENGTH_LONG).show(); } @Override public void onStopTrackingTouch(SeekBar seekBar) { Toast.makeText(CountActivity.this,“结束点击了！”,Toast.LENGTH_LONG).show(); } }); //开启一个线程，实现一秒钟进度增加10 new Thread(new Runnable() { @Override public void run() { int i=0; while(i<=100) { //进度变化 pb.setProgress(i); try { Thread.sleep(1000); } catch (InterruptedException e) { e.printStackTrace(); } i=i+10; } } }).start(); }}
日志文件
Process: com.example.hp.myapplication, PID: 24843 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.hp.myapplication/com.example.hp.myapplication.CountActivity}: java.lang.NullPointerException: Attempt to invoke virtual method ‘void android.widget.AutoCompleteTextView.setAdapter(android.widget.ListAdapter)’ on a null object reference at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) at android.app.ActivityThread.-wrap11(ActivityThread.java) at android.app.ActivityThread
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H.handleMessage(ActivityThread.java:1344) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:148) at android.app.ActivityThread.main(ActivityThread.java:5417) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit
H.handleMessage(ActivityThread.java:1344)atandroid.os.Handler.dispatchMessage(Handler.java:102)atandroid.os.Looper.loop(Looper.java:148)atandroid.app.ActivityThread.main(ActivityThread.java:5417)atjava.lang.reflect.Method.invoke(NativeMethod)atcom.android.internal.os.ZygoteInitMethodAndArgsCaller.run(ZygoteInit.java:726) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) Caused by: java.lang.NullPointerException: Attempt to invoke virtual method ‘void android.widget.AutoCompleteTextView.setAdapter(android.widget.ListAdapter)’ on a null object reference at com.example.hp.myapplication.CountActivity.onCreate(CountActivity.java:47) at android.app.Activity.performCreate(Activity.java:6237) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) at android.app.ActivityThread.-wrap11(ActivityThread.java) at android.app.ActivityThread
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H.handleMessage(ActivityThread.java:1344) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:148) at android.app.ActivityThread.main(ActivityThread.java:5417) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit
H.handleMessage(ActivityThread.java:1344) atandroid.os.Handler.dispatchMessage(Handler.java:102) atandroid.os.Looper.loop(Looper.java:148) atandroid.app.ActivityThread.main(ActivityThread.java:5417) atjava.lang.reflect.Method.invoke(NativeMethod) atcom.android.internal.os.ZygoteInitMethodAndArgsCaller.run(ZygoteInit.java:726) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 09-20 14:34:54.154 24843-24843/com.example.hp.myapplication I/Process: Sending signal. PID: 24843 SIG: 9
本文地址：https://blog.csdn.net/m0_50419564/article/details/108713112
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