Android Studios 应用程序崩溃

Question

我创建了一个需要 imageview 才能在 android studios 中打开新活动的应用程序。我让它工作但突然停止工作，现在当我选择我的图像视图时崩溃。 以下是我的代码：

public class Options extends AppCompatActivity {

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

    ImageView imgview1 =  (ImageView) findViewById(R.id.imageView1);
    imgview1.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Intent myIntent = new Intent(Options.this, PayorOrder.class);
            myIntent.putExtra("Table", 1);
            startActivity(myIntent);

        }
    });

    ImageView imgview2 =  (ImageView) findViewById(R.id.imageView2);
    imgview2.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Intent myIntent2 = new Intent(Options.this, PayorOrder.class);
            myIntent2.putExtra("Table", 2);
            startActivity(myIntent2);
        }
    });

    ImageView imgview3 =  (ImageView) findViewById(R.id.imageView3);
    imgview3.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Intent myIntent3 = new Intent(Options.this, PayorOrder.class);
            myIntent3.putExtra("Table", 3);
            startActivity(myIntent3);

        }
    });

    ImageView imgview4 =  (ImageView) findViewById(R.id.imageView4);
    imgview4.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Intent myIntent4 = new Intent(Options.this, PayorOrder.class);
            myIntent4.putExtra("Table", 4);
            startActivity(myIntent4);

        }
    });

    ImageView imgview5 =  (ImageView) findViewById(R.id.imageView5);
    imgview5.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Intent myIntent5 = new Intent(Options.this, PayorOrder.class);
            myIntent5.putExtra("Table", 5);
            startActivity(myIntent5);

        }
    });

    ImageView imgview6 =  (ImageView) findViewById(R.id.imageView6);
    imgview6.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Intent myIntent6 = new Intent(Options.this, PayorOrder.class);
            myIntent6.putExtra("Table", 6);
            startActivity(myIntent6);

        }
    });
}

}

有人知道它为什么不起作用吗？真的让我很困惑，谢谢

编辑：

04-17 23:16:27.940 1966-1966/com.example.ben.restaurantapp E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.ben.restaurantapp, PID: 1966
java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.ben.restaurantapp/com.example.ben.restaurantapp.PayorOrder}: java.lang.NullPointerException: Attempt to invoke virtual method 'int android.content.Intent.getIntExtra(java.lang.String, int)' on a null object reference
 at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2209)
 at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
 at android.app.ActivityThread.access$800(ActivityThread.java:144)
 at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
 at android.os.Handler.dispatchMessage(Handler.java:102)
 at android.os.Looper.loop(Looper.java:135)
 at android.app.ActivityThread.main(ActivityThread.java:5221)
 at java.lang.reflect.Method.invoke(Native Method)
 at java.lang.reflect.Method.invoke(Method.java:372)
 at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
 at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
 Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'int android.content.Intent.getIntExtra(java.lang.String, int)' on a null object reference
 at com.example.ben.restaurantapp.PayorOrder.<init>(PayorOrder.java:16)
 at java.lang.reflect.Constructor.newInstance(Native Method)
 at java.lang.Class.newInstance(Class.java:1572)
 at android.app.Instrumentation.newActivity(Instrumentation.java:1065)
 at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2199)
 at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360) 
 at android.app.ActivityThread.access$800(ActivityThread.java:144) 
 at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278) 
 at android.os.Handler.dispatchMessage(Handler.java:102) 
 at android.os.Looper.loop(Looper.java:135) 
 at android.app.ActivityThread.main(ActivityThread.java:5221) 
 at java.lang.reflect.Method.invoke(Native Method) 
 at java.lang.reflect.Method.invoke(Method.java:372) 
 at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899) 
 at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694) 

Edit2：支付或订单类：

public class PayorOrder extends AppCompatActivity {

Hashtable <Integer, DinnerTable> tables = new Hashtable<>();
DinnerTable currentTable = tables.get(getIntent().getIntExtra("Table", -1));

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

    Button btn = (Button) findViewById(R.id.btnOrder);
    btn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Intent myIntent = new Intent(PayorOrder.this, Menu.class);
            myIntent.putExtra("Table", (Parcelable) currentTable);
            startActivity(myIntent);
        }

    });

    if(tables.get(1) == null  )
    setupHashtable();
    Toast t = Toast.makeText(PayorOrder.this, String.valueOf(getIntent().getIntExtra("Table", -1)), Toast.LENGTH_SHORT);
    t.show();

}

private void setupHashtable() {
    for (int i = 1; i < 7; i++)
    {
        DinnerTable dt = new DinnerTable();
        dt.setTableNum(i);
        tables.put(dt.getTableNum(), dt);
    }
}
}

Answer 1

DinnerTable currentTable = tables.get(getIntent().getIntExtra("Table", -1));

有你的问题，需要调用getIntent().getIntExtra()方法，可以保证getIntent()不会为空。

将其更改为 DinnerTable currentTable;

然后在 onCreate 期间分配它

currentTable = tables.get(getIntent().getIntExtra("Table", -1));