App doesn't start, it is instantly force stopped (code below)

Question

I have been searching in my code for errors, but couldn't find any. Please help me, I need help. Note: I am a beginner in android and in android studio.

the problem is that there is no errors shown in android studio, but still i can't open the application on the phone.

This is my code

main.java

import android.support.v7.app.AppCompatActivity;



import android.os.Bundle;  
import android.view.View;  
import android.widget.Button;  
import android.widget.TextView;  

public class MainActivity extends AppCompatActivity {  
Button h,s,exit;  
    TextView t;  
    @Override  
    protected void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        setContentView(R.layout.activity_main);  
        h= (Button) findViewById(R.id.h);  
        t=(TextView) findViewById(R.id.t);  
        h.setOnClickListener(new View.OnClickListener() {  
            @Override  
            public void onClick(View v) {  
                t.setVisibility(v.INVISIBLE);  
                s.setVisibility(v.VISIBLE);  
                h.setVisibility(v.INVISIBLE);  
            }  
        });  
        s.setOnClickListener(new View.OnClickListener() {  
            @Override  
            public void onClick(View v) {  
                t.setVisibility(v.VISIBLE);  
                s.setVisibility(v.INVISIBLE);  
                h.setVisibility(v.VISIBLE);  
            }  
        });  
        exit.setOnClickListener(new View.OnClickListener(){  
            @Override  
           public void onClick(View v) {  
                finish();  
                System.exit(0);  
            }  
        });  

    }  
}

the layout main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
    android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity">

    <TextView android:text="@string/hello_world" android:layout_width="wrap_content"
        android:layout_height="wrap_content" android:id="@+id/t"
        android:layout_alignParentTop="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_marginTop="36dp" />
    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="hide"
        android:id="@+id/h"
        android:layout_below="@+id/t"
        android:layout_alignParentRight="true"
        android:layout_alignParentEnd="true" />
    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="show"
        android:id="@+id/s"
        android:layout_below="@+id/t"
        android:layout_alignParentRight="true"
        android:layout_alignParentEnd="true"
        android:visibility="invisible"/>
    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="exit"
        android:id="@+id/e"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true" />
</RelativeLayout>

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score 1 · Accepted Answer · answered Jul 18 '16 at 08:28

1

In your code you are using

s.setVisibility(v.VISIBLE);

But you did not initialize it in your MainActivity. Use:

s = (Button) findViewById(R.id.s);  
exit = (Button) findViewById(R.id.e);

answered Jul 18 '16 at 08:28

M.Waqas Pervez

2,492
2
19
33

score 0 · Answer 2 · answered Jul 18 '16 at 08:32

0

add these：

 s= (Button) findViewById(R.id.s);  
 exit= (Button) findViewById(R.id.e);

answered Jul 18 '16 at 08:32

niejun

1
1

App doesn't start, it is instantly force stopped (code below)

This is my code

2 Answers2