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如何检查复选框是否已选中？

[英]How to check if checkbox was checked?

 原文  2015-04-01 17:11:40  4   1    java/ android/ android-fragments

问题描述

我正在为Android创建测验应用程序。 我的前两个有3个片段和3个复选框。 在最后一个片段上有一个按钮，按下该按钮可打开一个名为“ End”的活动。 我需要在“结束”活动中出现一个选择了多少正确答案的结果。

首先，我试图检查它是否仅适用于第一个片段，但是我卡住了。 当我按下按钮时，应用程序关闭。

End.java ： 

       package bandymas.viewpagerexample;

import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.TextView;


public class End extends ActionBarActivity {

    private CheckBox checkBox1, checkBox2, checkBox3;
    private Button button;
    TextView newresult = (TextView)findViewById(R.id.textView1);


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

        addListenerOnButton();
    }

    private void addListenerOnButton() {

        checkBox1 = (CheckBox) findViewById(R.id.checkBox1);
        checkBox2 = (CheckBox) findViewById(R.id.checkBox2);
        checkBox3 = (CheckBox) findViewById(R.id.checkBox3);
        button = (Button) findViewById(R.id.button);

        button.setOnClickListener(new View.OnClickListener() {

            //Run when button is clicked
            @Override
            public void onClick(View v) {

                StringBuffer result = new StringBuffer();
                result.append("CheckBox1 : ").append(checkBox1.isChecked());
                result.append("\nCheckbox2 : ").append(checkBox2.isChecked());
                result.append("\nCheckBox3 :").append(checkBox3.isChecked());

                newresult.setText("My Awesome Text");
            }
        });
    }

    @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_naujas_baigimas, 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);
    }
}

这是我的日志 ： 

04-01 20:04:37.564    6020-6020/bandymas.viewpagerexample W/ApplicationPackageManager﹕ getCSCPackageItemText()
04-01 20:04:37.564    6020-6020/bandymas.viewpagerexample I/PersonaManager﹕ getPersonaService() name persona_policy
04-01 20:04:37.684    6020-6020/bandymas.viewpagerexample I/Adreno-EGL﹕ <qeglDrvAPI_eglInitialize:381>: EGL 1.4 QUALCOMM build:  (CL3869936)
    OpenGL ES Shader Compiler Version: 17.01.11.SPL
    Build Date: 01/17/14 Fri
    Local Branch:
    Remote Branch:
    Local Patches:
    Reconstruct Branch:
04-01 20:04:37.734    6020-6020/bandymas.viewpagerexample D/OpenGLRenderer﹕ Enabling debug mode 0
04-01 20:07:31.404    7094-7094/bandymas.viewpagerexample I/SELinux﹕ Function: selinux_android_load_priority [0], There is no sepolicy file.
04-01 20:07:31.404    7094-7094/bandymas.viewpagerexample I/SELinux﹕ Function: selinux_android_load_priority , priority version is VE=SEPF_GT-I9505_4.4.2_0033
04-01 20:07:31.404    7094-7094/bandymas.viewpagerexample I/SELinux﹕ selinux_android_seapp_context_reload: seapp_contexts file is loaded from /seapp_contexts
04-01 20:07:31.404    7094-7094/bandymas.viewpagerexample E/dalvikvm﹕ >>>>> Normal User
04-01 20:07:31.404    7094-7094/bandymas.viewpagerexample E/dalvikvm﹕ >>>>> bandymas.viewpagerexample [ userId:0 | appId:10229 ]
04-01 20:07:31.404    7094-7094/bandymas.viewpagerexample D/dalvikvm﹕ Late-enabling CheckJNI
04-01 20:07:31.584    7094-7094/bandymas.viewpagerexample W/ApplicationPackageManager﹕ getCSCPackageItemText()
04-01 20:07:31.594    7094-7094/bandymas.viewpagerexample I/PersonaManager﹕ getPersonaService() name persona_policy
04-01 20:07:31.794    7094-7094/bandymas.viewpagerexample I/Adreno-EGL﹕ <qeglDrvAPI_eglInitialize:381>: EGL 1.4 QUALCOMM build:  (CL3869936)
    OpenGL ES Shader Compiler Version: 17.01.11.SPL
    Build Date: 01/17/14 Fri
    Local Branch:
    Remote Branch:
    Local Patches:
    Reconstruct Branch:
04-01 20:07:31.844    7094-7094/bandymas.viewpagerexample D/OpenGLRenderer﹕ Enabling debug mode 0
04-01 20:07:42.454    7094-7094/bandymas.viewpagerexample W/ApplicationPackageManager﹕ getCSCPackageItemText()
04-01 20:07:42.485    7094-7094/bandymas.viewpagerexample I/dalvikvm﹕ Could not find method android.view.ViewGroup.onNestedScrollAccepted, referenced from method android.support.v7.internal.widget.ActionBarOverlayLayout.onNestedScrollAccepted
04-01 20:07:42.485    7094-7094/bandymas.viewpagerexample W/dalvikvm﹕ VFY: unable to resolve virtual method 11347: Landroid/view/ViewGroup;.onNestedScrollAccepted (Landroid/view/View;Landroid/view/View;I)V
04-01 20:07:42.485    7094-7094/bandymas.viewpagerexample D/dalvikvm﹕ VFY: replacing opcode 0x6f at 0x0000
04-01 20:07:42.485    7094-7094/bandymas.viewpagerexample I/dalvikvm﹕ Could not find method android.view.ViewGroup.onStopNestedScroll, referenced from method android.support.v7.internal.widget.ActionBarOverlayLayout.onStopNestedScroll
04-01 20:07:42.485    7094-7094/bandymas.viewpagerexample W/dalvikvm﹕ VFY: unable to resolve virtual method 11353: Landroid/view/ViewGroup;.onStopNestedScroll (Landroid/view/View;)V
04-01 20:07:42.485    7094-7094/bandymas.viewpagerexample D/dalvikvm﹕ VFY: replacing opcode 0x6f at 0x0000
04-01 20:07:42.485    7094-7094/bandymas.viewpagerexample I/dalvikvm﹕ Could not find method android.support.v7.internal.widget.ActionBarOverlayLayout.stopNestedScroll, referenced from method android.support.v7.internal.widget.ActionBarOverlayLayout.setHideOnContentScrollEnabled
04-01 20:07:42.485    7094-7094/bandymas.viewpagerexample W/dalvikvm﹕ VFY: unable to resolve virtual method 9041: Landroid/support/v7/internal/widget/ActionBarOverlayLayout;.stopNestedScroll ()V
04-01 20:07:42.485    7094-7094/bandymas.viewpagerexample D/dalvikvm﹕ VFY: replacing opcode 0x6e at 0x000e
04-01 20:07:42.495    7094-7094/bandymas.viewpagerexample I/dalvikvm﹕ Could not find method android.content.res.TypedArray.getChangingConfigurations, referenced from method android.support.v7.internal.widget.TintTypedArray.getChangingConfigurations
04-01 20:07:42.495    7094-7094/bandymas.viewpagerexample W/dalvikvm﹕ VFY: unable to resolve virtual method 365: Landroid/content/res/TypedArray;.getChangingConfigurations ()I
04-01 20:07:42.495    7094-7094/bandymas.viewpagerexample D/dalvikvm﹕ VFY: replacing opcode 0x6e at 0x0002
04-01 20:07:42.495    7094-7094/bandymas.viewpagerexample I/dalvikvm﹕ Could not find method android.content.res.TypedArray.getType, referenced from method android.support.v7.internal.widget.TintTypedArray.getType
04-01 20:07:42.495    7094-7094/bandymas.viewpagerexample W/dalvikvm﹕ VFY: unable to resolve virtual method 387: Landroid/content/res/TypedArray;.getType (I)I
04-01 20:07:42.495    7094-7094/bandymas.viewpagerexample D/dalvikvm﹕ VFY: replacing opcode 0x6e at 0x0002
04-01 20:07:42.525    7094-7094/bandymas.viewpagerexample D/AndroidRuntime﹕ Shutting down VM
04-01 20:07:42.525    7094-7094/bandymas.viewpagerexample W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0x4187fda0)
04-01 20:07:42.525    7094-7094/bandymas.viewpagerexample E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: bandymas.viewpagerexample, PID: 7094
    java.lang.RuntimeException: Unable to start activity ComponentInfo{bandymas.viewpagerexample/bandymas.viewpagerexample.End}: java.lang.NullPointerException
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2305)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2363)
            at android.app.ActivityThread.access$900(ActivityThread.java:161)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1265)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:157)
            at android.app.ActivityThread.main(ActivityThread.java:5356)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1265)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1081)
            at dalvik.system.NativeStart.main(Native Method)
     Caused by: java.lang.NullPointerException
            at bandymas.viewpagerexample.End.addListenerOnButton(End.java:33)
            at bandymas.viewpagerexample.End.onCreate(End.java:23)
            at android.app.Activity.performCreate(Activity.java:5426)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2269)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2363)
            at android.app.ActivityThread.access$900(ActivityThread.java:161)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1265)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:157)
            at android.app.ActivityThread.main(ActivityThread.java:5356)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1265)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1081)
            at dalvik.system.NativeStart.main(Native Method)

activity_end.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="bandymas.viewpagerexample.End">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:text="Result"
        android:id="@+id/textView1"
        android:layout_marginTop="100dp"
        android:textSize="40dp"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true" />

</RelativeLayout>

1 个解决方案

解决方案1
 0  2015-04-01 17:27:20

请检查activity_end.xml中是否有button(R.id.button) 。

我猜该按钮的ID在activity_end.xml中不存在。

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