按钮点击后应用程序崩溃

时间：2015-06-27 21:39:09

标签： java android

我试图创建一个跟踪锻炼的集合和代表的锻炼应用程序的模拟。

以下是布局的外观：

enter image description here

我尝试做的是当我按下NEW时，它会创建一个新的练习实例。练习包含一组集合。每个集合都包含一个名为Reps的整数变量。我想要做的是创建一个Exercise对象（在这个例子中是一个pullup）然后当我点击NEW它会创建一个新的Set来添加到列表中，当我按下TAP按钮它将更新集合的Rep值。所以最终我想得到一个集合列表，每个集合都有一个rep值。

例如：上拉：（5）（6）（5）（5）（3） 这是一套五组，第一组有5组，第二组有6组，第三组有5组，等等。

这是我写的代码：

Sets.java 

package com.example.soufin.pullupsv3;

/**
 * Created by Soufin on 6/26/2015.
 */
public class Sets {

  // private int _id;
  private int _reps;

  //constructor
  //Sets(int reps) {
  //   setReps(reps);
  //}

  //getter
  public int getReps()
  {
    return this._reps;
  }


  //setter
  public void setReps(int reps)
  {
    this._reps = reps;
  }

}

Exercise.java 

package com.example.soufin.pullupsv3;


import java.util.List;
import com.example.soufin.pullupsv3.Sets;

/**
 * Created by Soufin on 6/26/2015.
 */
public class Exercise {

    //public int ID;
    public String _name;
    public List<Sets> _sets;

    //getter
    public String getName()
    {
        return this._name;
    }
    //setter
    public void setName(String name)
    {
        this._name = name;
    }

    //getter
    public List getSets() {return this._sets; }
    // setter
   //public void setSets(int reps){this._sets.add(new Sets());}




}

Workout.java（主文件）

package com.example.soufin.pullupsv3;

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.TextView;
import android.R.*;

import com.example.soufin.pullupsv3.Sets;
import com.example.soufin.pullupsv3.Exercise;

import org.w3c.dom.Text;


public class Workout extends ActionBarActivity {

    Exercise pullup;
    Button wNew;
    Button wTap;
    Button wEnd;
    TextView displayText;
    int newIndex;
    int tapCount;
    int[] score = new int[5];
    boolean flag = false;
    String result;

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

        pullup = new Exercise();
        pullup.setName("Pullup");

        wNew = (Button) findViewById(R.id.newSetButton);
        wTap = (Button) findViewById(R.id.tapButton);
        wEnd = (Button) findViewById(R.id.endWorkoutButton);
        displayText = (TextView) findViewById(R.id.displayScore);


        wNew.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                Sets tempSet = new Sets(); // create new Set on click of mNew

                wTap.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        tapCount += 1; // increment based on number of taps
                    }
                });

                tempSet.setReps(tapCount);
                pullup._sets.add(tempSet); // add Set with reps (by taps) into List in Exercise
                result = pullup.getSets().toString(); //store result

            }
        });

        displayText.setText(result); //display result
    }

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

不幸的是，当我点击“新建”按钮时，应用程序崩溃了。

这是logcat所说的：

06-27 17:36:09.499    1236-1236/com.example.soufin.pullupsv3 D/dalvikvm﹕ Late-enabling CheckJNI
06-27 17:36:09.827    1236-1236/com.example.soufin.pullupsv3 I/dalvikvm﹕ Could not find method android.content.res.TypedArray.getChangingConfigurations, referenced from method android.support.v7.internal.widget.TintTypedArray.getChangingConfigurations
06-27 17:36:09.827    1236-1236/com.example.soufin.pullupsv3 W/dalvikvm﹕ VFY: unable to resolve virtual method 409: Landroid/content/res/TypedArray;.getChangingConfigurations ()I
06-27 17:36:09.827    1236-1236/com.example.soufin.pullupsv3 D/dalvikvm﹕ VFY: replacing opcode 0x6e at 0x0002
06-27 17:36:09.831    1236-1236/com.example.soufin.pullupsv3 I/dalvikvm﹕ Could not find method android.content.res.TypedArray.getType, referenced from method android.support.v7.internal.widget.TintTypedArray.getType
06-27 17:36:09.831    1236-1236/com.example.soufin.pullupsv3 W/dalvikvm﹕ VFY: unable to resolve virtual method 431: Landroid/content/res/TypedArray;.getType (I)I
06-27 17:36:09.831    1236-1236/com.example.soufin.pullupsv3 D/dalvikvm﹕ VFY: replacing opcode 0x6e at 0x0002
06-27 17:36:09.919    1236-1236/com.example.soufin.pullupsv3 D/dalvikvm﹕ GC_FOR_ALLOC freed 140K, 7% free 3308K/3520K, paused 15ms, total 16ms
06-27 17:36:09.935    1236-1236/com.example.soufin.pullupsv3 D/dalvikvm﹕ GC_FOR_ALLOC freed 4K, 6% free 3524K/3744K, paused 7ms, total 8ms
06-27 17:36:10.011    1236-1236/com.example.soufin.pullupsv3 I/dalvikvm-heap﹕ Grow heap (frag case) to 5.927MB for 2536932-byte allocation
06-27 17:36:10.019    1236-1242/com.example.soufin.pullupsv3 D/dalvikvm﹕ GC_FOR_ALLOC freed <1K, 4% free 6001K/6224K, paused 6ms, total 6ms
06-27 17:36:10.151    1236-1236/com.example.soufin.pullupsv3 D/libEGL﹕ loaded /system/lib/egl/libEGL_xap.so
06-27 17:36:10.151    1236-1236/com.example.soufin.pullupsv3 D/eglCodecCommon﹕ TcpStream::connect() - management hostname is 10.71.34.101
06-27 17:36:10.151    1236-1236/com.example.soufin.pullupsv3 D/eglCodecCommon﹕ TcpStream::connect() - connecting host: 10.71.34.1
06-27 17:36:10.171    1236-1236/com.example.soufin.pullupsv3 D/﹕ HostConnection::get() New Host Connection established 0xb8786ca8, tid 1236
06-27 17:36:10.171    1236-1236/com.example.soufin.pullupsv3 D/libEGL﹕ loaded /system/lib/egl/libGLESv1_CM_xap.so
06-27 17:36:10.175    1236-1236/com.example.soufin.pullupsv3 D/libEGL﹕ loaded /system/lib/egl/libGLESv2_xap.so
06-27 17:36:10.255    1236-1236/com.example.soufin.pullupsv3 W/EGL_xap﹕ eglSurfaceAttrib not implemented
06-27 17:36:10.255    1236-1236/com.example.soufin.pullupsv3 E/OpenGLRenderer﹕ Getting MAX_TEXTURE_SIZE from GradienCache
06-27 17:36:10.255    1236-1236/com.example.soufin.pullupsv3 E/OpenGLRenderer﹕ MAX_TEXTURE_SIZE: 16384
06-27 17:36:10.259    1236-1236/com.example.soufin.pullupsv3 E/OpenGLRenderer﹕ Getting MAX_TEXTURE_SIZE from Caches::initConstraints()
06-27 17:36:10.259    1236-1236/com.example.soufin.pullupsv3 E/OpenGLRenderer﹕ MAX_TEXTURE_SIZE: 16384
06-27 17:36:10.259    1236-1236/com.example.soufin.pullupsv3 D/OpenGLRenderer﹕ Enabling debug mode 0
06-27 17:36:15.815    1236-1236/com.example.soufin.pullupsv3 W/EGL_xap﹕ eglSurfaceAttrib not implemented
06-27 17:36:19.395    1236-1236/com.example.soufin.pullupsv3 D/AndroidRuntime﹕ Shutting down VM
06-27 17:36:19.395    1236-1236/com.example.soufin.pullupsv3 W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0xa4d6ab20)
06-27 17:36:19.403    1236-1236/com.example.soufin.pullupsv3 E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: com.example.soufin.pullupsv3, PID: 1236
    java.lang.NullPointerException
            at com.example.soufin.pullupsv3.Workout$1.onClick(Workout.java:59)
            at android.view.View.performClick(View.java:4438)
            at android.view.View$PerformClick.run(View.java:18422)
            at android.os.Handler.handleCallback(Handler.java:733)
            at android.os.Handler.dispatchMessage(Handler.java:95)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5017)
            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:779)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
            at dalvik.system.NativeStart.main(Native Method)

我做错了什么？我的代码的逻辑是否合适？

1 个答案:

答案 0 :(得分：0)

由于pullup._sets.add(tempSet)行会导致错误，因此有两种可能的罪魁祸首：pullup或_sets可能是null。进一步检查代码表明后者导致了问题。

要修复错误，您应该更改

public List<Sets> _sets;

到

private List<Sets> _sets = new ArrayList<Sets>();

请注意，我正在制作_sets变量private。这意味着其他类只能通过Exercise类的方法访问此变量。这被认为是一种很好的编程习惯。我建议您了解有关封装和数据隐藏的更多信息，以便更好地理解它。

与错误更直接相关的是我正在为ArrayList创建一个_sets对象来引用。这是至关重要的，因为否则_sets为null，这意味着它不会引用任何有效对象，从而导致您看到的NullPointerException。

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