Question

所以，如果知道这是一个新手就不明显了我正在与Intent合作开设一项新活动（Main2Activity）只要（Main2Activity）中没有任何内容，一切都很有效。

我在Main2Activity做任何事情的那一刻它崩溃了，
例如：

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.view.WindowManager;
import android.widget.Button;
import android.widget.CheckBox;
import butterknife.BindView;
import butterknife.ButterKnife;
import butterknife.OnClick;
public class MainActivity extends AppCompatActivity {
    @BindView(R.id.checkbox_diabetic)
    CheckBox diabetes;
    @BindView(R.id.firs_next_button)
    Button nextbutton;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ButterKnife.bind(this);        getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_HIDDEN);
    }
    @OnClick(R.id.firs_next_button)
    public void setNextbutton(View view) {
        Intent intent = new Intent(MainActivity.this, Main2Activity.class);
        startActivity(intent);
    }
}

和

package com.mhs.myapplication;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.CheckBox;

import butterknife.BindView;
import butterknife.OnClick;

public class Main2Activity extends AppCompatActivity {

    @BindView(R.id.diabetes_type_spinner)
    LabelledSpinner diabetestypes;
    @BindView(R.id.checkbox_diabetic)
    CheckBox diabetes;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main2);
        Intent intent = getIntent();
    }
}

它像魔术一样工作，活动开放没有任何问题。

但是当我向Main2activity添加一个东西时，它会在单击下一个按钮时崩溃。例如：

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.CheckBox;
import butterknife.BindView;
import butterknife.OnClick;

public class Main2Activity extends AppCompatActivity {
    @BindView(R.id.diabetes_type_spinner)
    LabelledSpinner diabetestypes;
    @BindView(R.id.checkbox_diabetic)
    CheckBox diabetes;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main2);
        Intent intent = getIntent();

        diabetestypes.setItemsArray(R.array.diabetes_type_list);
    }
}

崩溃报告：

E/AndroidRuntime: FATAL EXCEPTION: main
                  Process: com.mhs.myapplication, PID: 27891
                  java.lang.RuntimeException: Unable to start activity ComponentInfo{com.mhs.myapplication/com.mhs.myapplication.Main2Activity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void com.mhs.myapplication.LabelledSpinner.setItemsArray(int)' on a null object reference
                      at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2484)
                      at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2544)
                      at android.app.ActivityThread.access$900(ActivityThread.java:150)
                      at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1394)
                      at android.os.Handler.dispatchMessage(Handler.java:102)
                      at android.os.Looper.loop(Looper.java:168)
                      at android.app.ActivityThread.main(ActivityThread.java:5845)
                      at java.lang.reflect.Method.invoke(Native Method)
                      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:797)
                      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:687)
                   Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void com.mhs.myapplication.LabelledSpinner.setItemsArray(int)' on a null object reference
                      at com.mhs.myapplication.Main2Activity.onCreate(Main2Activity.java:22)
                      at android.app.Activity.performCreate(Activity.java:6248)
                      at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1125)
                      at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2437)
                      at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2544) 
                      at android.app.ActivityThread.access$900(ActivityThread.java:150) 
                      at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1394) 
                      at android.os.Handler.dispatchMessage(Handler.java:102) 
                      at android.os.Looper.loop(Looper.java:168) 
                      at android.app.ActivityThread.main(ActivityThread.java:5845) 
                      at java.lang.reflect.Method.invoke(Native Method) 
                      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:797) 
                      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:687)

Answer 1

Butter Knife并没有神奇地束缚这些观点。你必须添加

android:layout_alignWithParentIfMissing

到Task taskA = Task.Factory.StartNew(() => RunGet()); taskA.Wait(1000);也是如此。像这样：

ButterKnife.bind(this);

Answer 2

@tynn

所以不要做

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.CheckBox;
import butterknife.BindView;
import butterknife.OnClick;

public class Main2Activity extends AppCompatActivity {
    @BindView(R.id.diabetes_type_spinner)
    LabelledSpinner diabetestypes;
    @BindView(R.id.checkbox_diabetic)
    CheckBox diabetes;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main2);
        Intent intent = getIntent();

        diabetestypes.setItemsArray(R.array.diabetes_type_list);
    }
}

我做了

package com.mhs.myapplication;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.view.WindowManager;
import android.widget.LinearLayout;

import butterknife.ButterKnife;


public class Main2Activity extends AppCompatActivity {



    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main2);


        LabelledSpinner diabetess_type = (LabelledSpinner) findViewById(R.id.diabetes_type_spinner);
        diabetess_type.setItemsArray(R.array.diabetes_type_list);
        diabetess_type.setColor(R.color.white);
        LinearLayout linearLayout = (LinearLayout) findViewById(R.id.diabetes_layout);
        linearLayout.setVisibility(View.GONE);
       getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_HIDDEN);
            ButterKnife.bind(this);

        }

    }

}

令人惊讶的是，它有效

应用程序崩溃点击意图

2 个答案: