Android java.lang.IllegalStateException:找不到方法（视图）

我有一个简单的应用程序，三个屏幕上各有一个按钮。
前两个按钮应将您从一个意图发送到下一个意图，直到最后一个按钮拍摄照片并打印到第三个屏幕。
但当我添加了摄像头功能时，应用程序停止工作，现在当我按下第一个“开始spil”按钮时，它甚至不会移动到第二个意图

家庭活动

package com.example.daniel.proto;

import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;


public class Home extends ActionBarActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_home);
    }


    public void onClick(View view)
    {
        Intent i = new Intent(this, SelectLevel.class);
        startActivity(i);
    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_home, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}

SelectLevelActivity

package com.example.daniel.proto;

import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.content.Intent;


public class SelectLevel extends ActionBarActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_select_level);
    }

    public void onClick(View view)
    {
        Intent ii = new Intent (this, QRscanner.class);
        startActivity(ii);
    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_select_level, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}

QRS扫描无创性

package com.example.daniel.proto;

import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.graphics.Bitmap;
import android.provider.MediaStore;
import android.content.pm.PackageInfo;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;


public class QRscanner extends ActionBarActivity
{

    static final int REQUEST_IMAGE_CAPTURE = 1;
    ImageView photoImageView;


    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_qrscanner);

        Button photoButton = (Button) findViewById(R.id.photoButton);
        photoImageView = (ImageView) findViewById(R.id.photoImageView);

        //Disable the button if the user doesn't have a camera
        if(!hasCamera())
            photoButton.setEnabled(false);


    }

    //Check if the user has a camera
    private boolean hasCamera()
    {
        return getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA_ANY);
    }

    //Launching the camera
    public void launchCamera(View view)
    {
        Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
        //Take a picture and pass results along to onActivityResult
        startActivityForResult(intent, REQUEST_IMAGE_CAPTURE);

    }

    //If you want to return the image taken
    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        if(requestCode == REQUEST_IMAGE_CAPTURE && resultCode == RESULT_OK)
        {
            //Get the photo
            Bundle extras = data.getExtras();
            Bitmap photo = (Bitmap) extras.get("data");
            photoImageView.setImageBitmap(photo);
        }
    }
}

家庭XML

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
    android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".Home"
    android:background="#009900">

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Start Spil"
        android:id="@+id/playButton"
        android:layout_centerVertical="true"
        android:layout_centerHorizontal="true"
        android:onClick=""
        />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceLarge"
        android:text="QuesteX"
        android:id="@+id/textView"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="36dp"
        android:textSize="40dp" />

</RelativeLayout>

---

您意外地从android内部删除了该方法：单击按钮

更改：

android:onClick=""

致：

---

在第一个活动中，有一个名为onClick（视图）的方法。它将被称为playButton的点击按钮调用。但是在xml布局文件中，必须在onClick标记中提到方法名称。否则，您必须在活动中编写侦听器，如下所示：

button.setOnClickListener(new View.OnClickListener() {
         public void onClick(View v) {
             // Perform action on click
         }
     });

并移除该标签：

android:onClick=""

---

您忘记在“问题”上附加图标。或者，你忘了首先自己解决问题

android:onClick=""

android:onClick="onClick"

button.setOnClickListener(new View.OnClickListener() {
         public void onClick(View v) {
             // Perform action on click
         }
     });

android:onClick=""