的Android按鈕調用另一個函數

我嘗試使用我的Android按鈕來更改at_command的Android按鈕調用另一個函數

如果我在btnLeftListener調用"intOfFloat(float f)"的價值的logcat將顯示

01-23 16:17:28.610: E/AndroidRuntime(1154): java.lang.NullPointerException

請幫我解決這個:)

String at_cmd = ""; 
FloatBuffer fb; 
IntBuffer ib; 
int PORT=5556; 
float speed = (float)0.1; 
int seq = 1; 
@Override 
public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState);  
    btnLeft=(Button)findViewById(R.id.LeftBtn); 
    btnLeft.setOnClickListener(btnLeftListener); 
} 
public Button.OnClickListener btnLeftListener= 
     new Button.OnClickListener(){ 
     @Override 
     public void onClick(View arg0) { 
      at_cmd = "AT*PCMD=" + (seq++) + ",1," + intOfFloat(-speed)+",0,0,0"; 
    } 

}; 
public int intOfFloat(float f) { 
    fb.put(0, f); 
    return ib.get(0); 
}

logcat的

01-23 16:17:28.591: W/dalvikvm(1154): threadid=1: thread exiting with uncaught exception (group=0x40a13300) 
01-23 16:17:28.610: E/AndroidRuntime(1154): FATAL EXCEPTION: main 
01-23 16:17:28.610: E/AndroidRuntime(1154): java.lang.NullPointerException 
01-23 16:17:28.610: E/AndroidRuntime(1154):  at com.example.dronedivideandroid.DroneMain.intOfFloat(DroneMain.java:60) 
01-23 16:17:28.610: E/AndroidRuntime(1154):  at com.example.dronedivideandroid.DroneMain$1.onClick(DroneMain.java:70) 
01-23 16:17:28.610: E/AndroidRuntime(1154):  at android.view.View.performClick(View.java:4084) 
01-23 16:17:28.610: E/AndroidRuntime(1154):  at android.view.View$PerformClick.run(View.java:16966) 
01-23 16:17:28.610: E/AndroidRuntime(1154):  at android.os.Handler.handleCallback(Handler.java:615) 
01-23 16:17:28.610: E/AndroidRuntime(1154):  at android.os.Handler.dispatchMessage(Handler.java:92) 
01-23 16:17:28.610: E/AndroidRuntime(1154):  at android.os.Looper.loop(Looper.java:137) 
01-23 16:17:28.610: E/AndroidRuntime(1154):  at android.app.ActivityThread.main(ActivityThread.java:4745) 
01-23 16:17:28.610: E/AndroidRuntime(1154):  at java.lang.reflect.Method.invokeNative(Native Method) 
01-23 16:17:28.610: E/AndroidRuntime(1154):  at java.lang.reflect.Method.invoke(Method.java:511) 
01-23 16:17:28.610: E/AndroidRuntime(1154):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786) 
01-23 16:17:28.610: E/AndroidRuntime(1154):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553) 
01-23 16:17:28.610: E/AndroidRuntime(1154):  at dalvik.system.NativeStart.main(Native Method) 
01-23 16:17:28.631: W/ActivityManager(163): Force finishing activity com.example.dronedivideandroid/.DroneMain 
01-23 16:17:28.641: W/WindowManager(163): Failure taking screenshot for (246x410) to layer 21010 
01-23 16:17:29.150: W/ActivityManager(163): Activity pause timeout for ActivityRecord{4154a830 com.example.dronedivideandroid/.DroneMain} 
01-23 16:17:29.351: I/Choreographer(262): Skipped 37 frames! The application may be doing too much work on its main thread. 
01-23 16:17:30.591: I/Process(1154): Sending signal. PID: 1154 SIG: 9 
01-23 16:17:30.601: I/ActivityManager(163): Process com.example.dronedivideandroid (pid 1154) has died. 
01-23 16:17:30.601: I/WindowState(163): WIN DEATH: Window{414043e0 com.example.dronedivideandroid/com.example.dronedivideandroid.DroneMain paused=false} 
01-23 16:17:30.691: W/InputMethodManagerService(163): Got RemoteException sending setActive(false) notification to pid 1154 uid 10047 
01-23 16:17:40.091: W/ActivityManager(163): Activity destroy timeout for ActivityRecord{4154a830 com.example.dronedivideandroid/.DroneMain} 
01-23 16:19:52.800: D/dalvikvm(248): GC_CONCURRENT freed 383K, 7% free 8537K/9095K, paused 6ms+5ms, total 46ms 
01-23 16:23:49.971: E/ThrottleService(163): problem during onPollAlarm: java.lang.IllegalStateException: problem parsing stats: java.io.FileNotFoundException: /proc/net/xt_qtaguid/iface_stat_all: open failed: ENOENT (No such file or directory) 
01-23 16:27:27.310: D/dalvikvm(248): GC_CONCURRENT freed 384K, 7% free 8537K/9095K, paused 17ms+6ms, total 56ms

來源

2013-01-23 DekangHu

發佈整個logcat輸出 –

fb＆ib設置爲什麼？ btnLeftListener在哪裏使用？ –

** Button.onClickListener **類在哪裏？我希望它應該是** View.onClickListener ** – Zoombie

可能，這將是正確的答案BEC我測試了在設備前確保變量fb和ib被初始化（NOT NULL）...... !!!!!

import java.nio.FloatBuffer; 
import java.nio.IntBuffer; 

import android.os.Bundle; 
import android.app.Activity; 
import android.util.Log; 
import android.view.Menu; 
import android.view.View; 
import android.view.View.OnClickListener; 
import android.widget.Button; 

public class MainActivity extends Activity { 
String at_cmd = ""; 
FloatBuffer fb; 
IntBuffer ib; 
int PORT=5556; 
float speed = (float)0.1; 
int seq = 1; 
@Override 
public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 
    Button btnLeft=(Button)findViewById(R.id.button1); 
    btnLeft.setOnClickListener(btnLeftListener); 
} 
public OnClickListener btnLeftListener= 
     new OnClickListener(){ 


    @Override 
    public void onClick(View arg0) { 
     at_cmd = "AT*PCMD=" + String.valueOf(seq++) + ",1," + intOfFloat(-speed)+",0,0,0"; 

     System.out.println("Ans----->"+at_cmd); 
    } 

}; 
public int intOfFloat(float f) { 
    if(fb != null) fb.put(0, f); 
    if(ib != null) return ib.get(0); 
    else return 0; 

} 

}

而且我得到了以下輸出...... !!!

AT * PCMD = 1,1,0,0,0,0。

其他檢查出來...... !!!!!!!

來源

2013-01-23 10:00:33

您的變量中的一個沒有初始化，所以你應該確保以下瓦爾有一個值：

seq，speed，fb，ib。

來源

2013-01-23 08:30:47 thepoosh

使用它們

public int intOfFloat(float f) { 
if(fb != null) fb.put(0, f); 
if(ib != null) return ib.get(0); 
else return 0; 
}

來源

2013-01-23 08:30:55 Nermeen

的Android按鈕調用另一個函數

回答

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