3活动计时器会产生无效错误

Question

我有3个活动：

• 您设置倒数计时器启动的数字
的计时器设置
• 计时器本身
• 按下后面按钮时被激活

我的问题是，在按下"简历"按钮时，在暂停计时器活动(第三个(中，应用程序显示空错误，但是按下主菜单按钮时，应用程序正常工作。

第一次活动

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_timer_settings);
    final NumberPicker np = (NumberPicker)findViewById(R.id.numberPicker2);
    np.setMinValue(1);
    np.setMaxValue(999);
    np.setWrapSelectorWheel(false);
    final Button testbutton = (Button) findViewById(R.id.testbutton);
    testbutton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Intent testintent = new Intent(timer_settings.this, timer_2.class);
            Bundle timer2extras = new Bundle();
            timer2extras.putString("timer2string", np.getValue() + "");
            testintent.putExtras(timer2extras);
            startActivity(testintent);
        }
    });
}

第二个活动

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_timer_2);
    //...        
    Bundle timer2extras = getIntent().getExtras();
    String timer2string = timer2extras.getString("timer2string");
    starttime = Integer.parseInt(timer2string);
    starttimeup = starttime*60000;
    starttimedown = starttime*60000;
    int minutes_up_start = (int) (starttimeup / 1000) / 60;
    int seconds_up_start = (int) (starttimeup / 1000) % 60;
    String time_2_up_start_formatted = 
    String.format(Locale.getDefault(),"%02d:%02d", minutes_up_start, 
    seconds_up_start);
    timer_2_up.setText(time_2_up_start_formatted);
    int minutes_down_start = (int) (starttimedown / 1000) / 60;
    int seconds_down_start = (int) (starttimedown / 1000) % 60;
    String time_2_down_start_formatted = 
    String.format(Locale.getDefault(),"%02d:%02d", minutes_down_start, 
    seconds_down_start);
    timer_2_down.setText(time_2_down_start_formatted);
    //...

@Override
public void onBackPressed()
{
    startActivity(new Intent(timer_2.this, timer_2_pause.class));
}

第三活动

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_timer_2_pause);
    this.setFinishOnTouchOutside(false);
    Button main = (Button)findViewById(R.id.button8);
    Button resu = (Button)findViewById(R.id.button7);
    main.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Intent mainintent = new Intent(timer_2_pause.this, main_menu.class);
            startActivity(mainintent);
        }
    });
    resu.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Intent resuintent = new Intent(timer_2_pause.this, timer_2.class);
            startActivity(resuintent);
        }
    });
}

Answer 1

您的活动两个期望从意图中获取一些数据。

Bundle timer2extras = getIntent().getExtras();
String timer2string = timer2extras.getString("timer2string");

您的timer2extras为null，当您尝试从中获取字符串时，它会导致Null指针异常。

Answer 2

通过更改简历来修复它：

 resu.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            finish();
        }
    });