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社区首页 >问答首页 >如何使“if(在本地找到字符串){.}”

问如何使“if(在本地找到字符串){.}”
EN

Stack Overflow用户
提问于 2015-11-10 18:36:08
回答 2查看 46关注 0票数 0

我想做一个int语句，这样如果有一个字符串保存在本地数据库中，那么做什么都行。我试过：

代码语言：javascript
运行
复制
public class DispatchActivity extends Activity {
    SharedPreferences sharedPref;
    SharedPreferences.Editor editor;
    @Override
    public void onCreate(Bundle savedInstanceState){
        super.onCreate(savedInstanceState);
        sharedPref= getSharedPreferences("myPref", Context.MODE_PRIVATE);
        editor=sharedPref.edit();
        String userIDsaved = sharedPref.getString("user_id", "");
    if(userIDsaved==null){
        Intent startSignUpActivity = new Intent(DispatchActivity.this,SignUpActivity.class);
        DispatchActivity.this.startActivity(startSignUpActivity);
    }
        else{
        Intent startMainActivity = new Intent(DispatchActivity.this,MainActivity.class);
        DispatchActivity.this.startActivity(startMainActivity);
    }
...

然而，当我这样做的时候，应用程序就崩溃了。这是一个分派活动，意思是如果在本地找到了一个字符串，那么就启动这个mainactivity。如果没有，就开始注册活动。即使我在本地保存了一个字符串，它也会崩溃。请告诉我怎么做我提到的事

撞车日志：

代码语言：javascript
运行
复制
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime: FATAL EXCEPTION: main
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime: Process: com.alibdeir.signupactivity, PID: 20326
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime: java.lang.RuntimeException: Unable to start activity ComponentInfo{com.alibdeir.signupactivity/com.alibdeir.signupactivity.MainActivity}: android.view.InflateException: Binary XML file line #20: Error inflating class android.support.design.widget.FloatingActionButton
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2413)
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2471)
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.app.ActivityThread.access$900(ActivityThread.java:175)
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1308)
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.os.Handler.dispatchMessage(Handler.java:102)
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.os.Looper.loop(Looper.java:146)
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.app.ActivityThread.main(ActivityThread.java:5602)
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at java.lang.reflect.Method.invokeNative(Native Method)
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at java.lang.reflect.Method.invoke(Method.java:515)
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1283)
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1099)
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at dalvik.system.NativeStart.main(Native Method)
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:  Caused by: android.view.InflateException: Binary XML file line #20: Error inflating class android.support.design.widget.FloatingActionButton
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.view.LayoutInflater.createView(LayoutInflater.java:626)
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:702)
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.view.LayoutInflater.rInflate(LayoutInflater.java:761)
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.view.LayoutInflater.inflate(LayoutInflater.java:498)
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.view.LayoutInflater.inflate(LayoutInflater.java:398)
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.view.LayoutInflater.inflate(LayoutInflater.java:354)
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.support.v7.app.AppCompatDelegateImplV7.setContentView(AppCompatDelegateImplV7.java:257)
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:109)
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at com.alibdeir.signupactivity.MainActivity.onCreate(MainActivity.java:20)
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.app.Activity.performCreate(Activity.java:5451)
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1093)
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2377)
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2471) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.app.ActivityThread.access$900(ActivityThread.java:175) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1308) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.os.Handler.dispatchMessage(Handler.java:102) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.os.Looper.loop(Looper.java:146) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.app.ActivityThread.main(ActivityThread.java:5602) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at java.lang.reflect.Method.invokeNative(Native Method) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at java.lang.reflect.Method.invoke(Method.java:515) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1283) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1099) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at dalvik.system.NativeStart.main(Native Method) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:  Caused by: java.lang.reflect.InvocationTargetException
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at java.lang.reflect.Constructor.constructNative(Native Method)
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.view.LayoutInflater.createView(LayoutInflater.java:600)
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:702) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.view.LayoutInflater.rInflate(LayoutInflater.java:761) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.view.LayoutInflater.inflate(LayoutInflater.java:498) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.view.LayoutInflater.inflate(LayoutInflater.java:398) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.view.LayoutInflater.inflate(LayoutInflater.java:354) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.support.v7.app.AppCompatDelegateImplV7.setContentView(AppCompatDelegateImplV7.java:257) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:109) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at com.alibdeir.signupactivity.MainActivity.onCreate(MainActivity.java:20) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.app.Activity.performCreate(Activity.java:5451) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1093) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2377) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2471) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.app.ActivityThread.access$900(ActivityThread.java:175) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1308) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.os.Handler.dispatchMessage(Handler.java:102) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.os.Looper.loop(Looper.java:146) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.app.ActivityThread.main(ActivityThread.java:5602) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at java.lang.reflect.Method.invokeNative(Native Method) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at java.lang.reflect.Method.invoke(Method.java:515) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1283) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1099) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at dalvik.system.NativeStart.main(Native Method) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:  Caused by: android.content.res.Resources$NotFoundException: File res/drawable/ic_vpn_key_24dp.xml from drawable resource ID #0x7f020047
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.content.res.Resources.loadDrawable(Resources.java:3440)
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.content.res.TypedArray.getDrawable(TypedArray.java:602)
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.widget.ImageView.<init>(ImageView.java:133)
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.widget.ImageButton.<init>(ImageButton.java:88)
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.support.design.widget.FloatingActionButton.<init>(FloatingActionButton.java:106)
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.support.design.widget.FloatingActionButton.<init>(FloatingActionButton.java:102)
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at java.lang.reflect.Constructor.constructNative(Native Method) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at java.lang.reflect.Constructor.newInstance(Constructor.java:423) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.view.LayoutInflater.createView(LayoutInflater.java:600) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:702) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.view.LayoutInflater.rInflate(LayoutInflater.java:761) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.view.LayoutInflater.inflate(LayoutInflater.java:498) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.view.LayoutInflater.inflate(LayoutInflater.java:398) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.view.LayoutInflater.inflate(LayoutInflater.java:354) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.support.v7.app.AppCompatDelegateImplV7.setContentView(AppCompatDelegateImplV7.java:257) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:109) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at com.alibdeir.signupactivity.MainActivity.onCreate(MainActivity.java:20) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.app.Activity.performCreate(Activity.java:5451) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1093) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2377) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2471) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.app.ActivityThread.access$900(ActivityThread.java:175) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1308) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.os.Handler.dispatchMessage(Handler.java:102) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.os.Looper.loop(Looper.java:146) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.app.ActivityThread.main(ActivityThread.java:5602) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at java.lang.reflect.Method.invokeNative(Native Method) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at java.lang.reflect.Method.invoke(Method.java:515) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1283) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1099) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at dalvik.system.NativeStart.main(Native Method) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:  Caused by: org.xmlpull.v1.XmlPullParserException: Binary XML file line #1: invalid drawable tag vector
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.graphics.drawable.Drawable.createFromXmlInner(Drawable.java:986)
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.graphics.drawable.Drawable.createFromXml(Drawable.java:930)
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.content.res.Resources.loadDrawable(Resources.java:3436)
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.content.res.TypedArray.getDrawable(TypedArray.java:602) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.widget.ImageView.<init>(ImageView.java:133) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.widget.ImageButton.<init>(ImageButton.java:88) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.support.design.widget.FloatingActionButton.<init>(FloatingActionButton.java:106) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.support.design.widget.FloatingActionButton.<init>(FloatingActionButton.java:102) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at java.lang.reflect.Constructor.constructNative(Native Method) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at java.lang.reflect.Constructor.newInstance(Constructor.java:423) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.view.LayoutInflater.createView(LayoutInflater.java:600) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:702) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.view.LayoutInflater.rInflate(LayoutInflater.java:761) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.view.LayoutInflater.inflate(LayoutInflater.java:498) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.view.LayoutInflater.inflate(LayoutInflater.java:398) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.view.LayoutInflater.inflate(LayoutInflater.java:354) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.support.v7.app.AppCompatDelegateImplV7.setContentView(AppCompatDelegateImplV7.java:257) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:109) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at com.alibdeir.signupactivity.MainActivity.onCreate(MainActivity.java:20) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.app.Activity.performCreate(Activity.java:5451) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1093) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2377) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2471) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.app.ActivityThread.access$900(ActivityThread.java:175) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1308) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.os.Handler.dispatchMessage(Handler.java:102) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.os.Looper.loop(Looper.java:146) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at android.app.ActivityThread.main(ActivityThread.java:5602) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at java.lang.reflect.Method.invokeNative(Native Method) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at java.lang.reflect.Method.invoke(Method.java:515) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1283) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1099) 
11-11 20:39:40.199 20326-20326/com.alibdeir.signupactivity E/AndroidRuntime:     at dalvik.system.NativeStart.main(Native Method) 
android
if-statement
sharedpreferences
EN

回答 2

Stack Overflow用户

回答已采纳

发布于 2015-11-11 18:47:21

这条线在哪里？

代码语言：javascript
运行
复制
setContentView(R.layout.dispatch_activity);

我看不出在什么地方膨胀了MainActivity的XML文件。这应该是super.onCreate(SavedInstanceState)之后的第二行；在onCreate方法中。

另外，查看MainActivity文件，特别是创建FloatingActionButton的位置。似乎您可能有一个类型与此视图，因为它有困难的膨胀。

或

没有将正确的导入添加到FloatingActionButton (v7设计支持库)的支持库中。

确保它在您的gradle文件中：

代码语言：javascript
运行
复制
compile 'com.android.support:design:23.0.1'

这个问题出现在您的MainActivity XML文件中，因为logcat输出告诉您这一点！

以下是我如何知道出了什么问题(从您链接的logcat输出！)

代码语言：javascript
运行
复制
Caused by: android.view.InflateException: Binary XML file line #20: Error inflating class android.support.design.widget.FloatingActionButton

此外，我们还有：

代码语言：javascript
运行
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Caused by: android.content.res.Resources$NotFoundException: File res/drawable/ic_vpn_key_24dp.xml from drawable resource ID #0x7f020047

这导致我假设您的FloatingActionButton的图标可能没有在可绘图/mipmap文件夹中找到。

票数 1
EN

Stack Overflow用户

发布于 2015-11-10 18:47:01

您应该将默认值指定为NULL，因为您也可以将一些空值保存为字符串，尽管不应该发生崩溃。但你可能会这样：

代码语言：javascript
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public class DispatchActivity extends Activity {

    SharedPreferences sharedPref;
    SharedPreferences.Editor editor;

    @Override
    public void onCreate(Bundle savedInstanceState){
        super.onCreate(savedInstanceState);

        sharedPref = getSharedPreferences("myPref", Context.MODE_PRIVATE);
        editor = sharedPref.edit();
        String userIDsaved = sharedPref.getString("user_id", null);

        if(null == userIDsaved){ //you can also check || userIDsaved.isEmpty()
            startActivity(new Intent(this,SignUpActivity.class));
        } else{
            startActivity(new Intent(this,MainActivity.class));
        }
    }
}
票数 0
EN
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：

https://stackoverflow.com/questions/33637108

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