Android Studio：如何解决此执行错误

Question

我是 android studio 的新手，我不明白为什么当我开始使用搜索栏时我的应用程序崩溃了。有人可以帮我吗？公共类 MainActivity 扩展 AppCompatActivity { SeekBar seeBar; //声明seekbar对象TextView textView, textView2; 列表视图简单列表视图；//为SeekBar声明成员变量 int离散; int开始= 50；int 起始位置 = 50; //进度跟踪器 int temp = 0; //为ViewStub声明对象ViewStub存根; 复选框复选框；列表视图lv; //声明Listview对象Button按钮; 查看视图；public MainActivity() {    discrete = 0;}@Overridepublic void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_main);    //declare viewstub object    stub = findViewById(R.id.viewStub1);    @SuppressWarnings("unused")    View inflated = stub.inflate();    stub.setVisibility(View.INVISIBLE);    //ViewStub logic    checkBox = findViewById(R.id.checkBox1);    //handle checkbox click event    checkBox.setOnCheckedChangeListener(new CheckBox.OnCheckedChangeListener(){        public void onCheckedChanged(CompoundButton arg0, boolean isChecked) {            if (isChecked) {                //remove objs from parent view to allow for child view objs                checkBox.setVisibility(View.GONE);                seekBar.setVisibility(View.GONE);                textView.setVisibility(View.GONE);                stub.setVisibility(View.VISIBLE);            }        }    });    //seekbar logic    textView = findViewById(R.id.textview);    textView = findViewById(R.id.textView2);    textView.setText(" Celsius at 0 degrees");    //set default view    seekBar = findViewById(R.id.seekbar);    seekBar.setProgress(start_position);    //create event handler for SeekBar    seekBar.setOnSeekBarChangeListener(new OnSeekBarChangeListener(){        @Override        public void onStopTrackingTouch(SeekBar seekBar) {            if (temp == 0) {                //for initial view result                //Toast.makeText(getBaseContext(), "Fahrenheit result: 32 degrees",                        //Toast.LENGTH_SHORT).show();                textView2.setText("Fahrenheit result 32 degrees") ;            }

Answer 1

TextView textView = findViewById(R.id.textview); TextView textView2 = findViewById(R.id.textView2);

Answer 2

textView = findViewById(R.id.textview);
textView = findViewById(R.id.textView2);

textView2 此处未初始化...

将上面的代码改为

textView = findViewById(R.id.textview);
textView2 = findViewById(R.id.textView2);

Answer 3

初始化textView2 你似乎错过了那部分