Question

这是问题所在

E / Android运行时：致命异常：主要流程：abuhashesh.homam.myfirstapp，PID：5379 java.lang.RuntimeException：无法实例化活动 ComponentInfo {abuhashesh.homam.myfirstapp / abuhashesh.homam.myfirstapp.Activity_2}： java.lang.NullPointerException：尝试调用虚拟方法上的“ android.view.Window $ Callback android.view.Window.getCallback（）” 空对象引用在android.app.ActivityThread.performLaunchActivity（ActivityThread.java:2209）在android.app.ActivityThread.handleLaunchActivity（ActivityThread.java:2360）在android.app.ActivityThread.access $ 800（ActivityThread.java:144）在android.app.ActivityThread $ H.handleMessage（ActivityThread.java:1278）在android.os.Handler.dispatchMessage（Handler.java:102）在android.os.Looper.loop（Looper.java:135）在android.app.ActivityThread.main（ActivityThread.java:5221）在java.lang.reflect.Method.invoke（本机方法）在java.lang.reflect.Method.invoke（Method.java:372）在com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:899）在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:694）原因：java.lang.NullPointerException：尝试调用虚拟方法'android.view.Window $ Callback 空对象引用上的android.view.Window.getCallback（）' 在android.support.v7.app.AppCompatDelegateImplBase。（AppCompatDelegateImplBase.java:117）在android.support.v7.app.AppCompatDelegateImplV9。（AppCompatDelegateImplV9.java:149）在android.support.v7.app.AppCompatDelegateImplV14。（AppCompatDelegateImplV14.java:56）在android.support.v7.app.AppCompatDelegate.create（AppCompatDelegate.java:202）在android.support.v7.app.AppCompatDelegate.create（AppCompatDelegate.java:183）在android.support.v7.app.AppCompatActivity.getDelegate（AppCompatActivity.java:519）在android.support.v7.app.AppCompatActivity.findViewById（AppCompatActivity.java:190）在abuhashesh.homam.myfirstapp.Activity_2。（Activity_2.java:144）在java.lang.reflect.Constructor.newInstance（本地方法）在java.lang.Class.newInstance（Class.java:1572）在android.app.Instrumentation.newActivity（Instrumentation.java:1065）在android.app.ActivityThread.performLaunchActivity（ActivityThread.java:2199）在android.app.ActivityThread.handleLaunchActivity（ActivityThread.java:2360）在android.app.ActivityThread.access $ 800（ActivityThread.java:144）在android.app.ActivityThread $ H.handleMessage（ActivityThread.java:1278）在android.os.Handler.dispatchMessage（Handler.java:102）在android.os.Looper.loop（Looper.java:135）在android.app.ActivityThread.main（ActivityThread.java:5221）在java.lang.reflect.Method.invoke（本机方法）在java.lang.reflect.Method.invoke（Method.java:372）在com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:899）在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:694）

我的第一个活动课：

package abuhashesh.homam.myfirstapp;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

import java.util.Calendar;

public class Activity1 extends AppCompatActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_1);

    Button gototwo=(Button)findViewById(R.id.button2);
    gototwo.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Intent ionetotwo=new 
Intent(getApplicationContext(),Activity_2.class);
            startActivity(ionetotwo);
        }
    });
}
public void Buage(View view) {
    EditText Year=(EditText)findViewById(R.id.editText);
    Calendar c=Calendar.getInstance();
    int Current_year =c.get(Calendar.YEAR);
    int YearOfBirth=Integer.parseInt(Year.getText().toString());
    int age=Current_year-YearOfBirth;
    Toast.makeText(this,"age:"+String.valueOf(age),Toast.LENGTH_LONG).show();

}

}

my second activity class:

package abuhashesh.homam.myfirstapp;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

公共类Activity_2扩展了AppCompatActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity2);

    zero.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            theoper.setText(theoper.getText().toString()+"0");
        }
    });
    one.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            theoper.setText(theoper.getText().toString()+"1");
        }
    });
    two.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            theoper.setText(theoper.getText().toString()+"2");
        }
    });
    three.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            theoper.setText(theoper.getText().toString()+"3");
        }
    });
    four.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            theoper.setText(theoper.getText().toString()+"4");
        }
    });
    five.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            theoper.setText(theoper.getText().toString()+"5");
        }
    });
    six.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            theoper.setText(theoper.getText().toString()+"6");
        }
    });
    seven.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            theoper.setText(theoper.getText().toString()+"7");
        }
    });
    eight.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            theoper.setText(theoper.getText().toString()+"8");
        }
    });
    nine.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            theoper.setText(theoper.getText().toString()+"9");
        }
    });
    equal.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            theoper.setText(theoper.getText().toString()+"0");
        }
    });
    sum.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            theoper.setText(theoper.getText().toString()+"0");
        }
    });
    min.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            theoper.setText(theoper.getText().toString()+"0");
        }
    });
    multi.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            theoper.setText(theoper.getText().toString()+"0");
        }
    });
    div.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            theoper.setText(theoper.getText().toString()+"0");
        }
    });
    clear.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            theoper.setText("");
        }
    });

        }
Button zero=(Button)findViewById(R.id.bu10);
Button one=(Button)findViewById(R.id.bu1);
Button two=(Button)findViewById(R.id.bu2);
Button three=(Button)findViewById(R.id.bu3);
Button four=(Button)findViewById(R.id.bu4);
Button five=(Button)findViewById(R.id.bu5);
Button six=(Button)findViewById(R.id.bu6);
Button seven=(Button)findViewById(R.id.bu7);
Button eight=(Button)findViewById(R.id.bu8);
Button nine=(Button)findViewById(R.id.bu9);
Button clear=(Button)findViewById(R.id.buclear);
Button sum=(Button)findViewById(R.id.bu11);
Button min=(Button)findViewById(R.id.bu12);
Button multi=(Button)findViewById(R.id.bu13);
Button div=(Button)findViewById(R.id.bu14);
Button equal=(Button)findViewById(R.id.bu15);
TextView theoper=(TextView)findViewById(R.id.textView4);
TextView Res=(TextView)findViewById(R.id.textView5);

}

意向不适用于android studio

0 个答案: