Activity has been stopped

Question

this is the code when i apply that code application has been stopped occurred this code is to find relative prime in android application development check and let me know my error thanks in advance

relative.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String A = num1.getText().toString();
String B = num2.getText().toString();
int val1 = Integer.parseInt(A);
int val2 = Integer.parseInt(B);
int gcd = 1;
// Function to find GCD for relative prime
while (val1 != val2) {
if (val1 > val2)
val1 = val1 - val2;
else
val2 = val2 - val1;
}
String ans = String.valueOf(val1);
String ans1 = String.valueOf(val2);
// function to check and print if
// two numbers are co-prime or not
if (ans1.equals(1)) {
result.setText("Relative Prime");
Toast.makeText(MainActivity.this, "Relative Prime", 
Toast.LENGTH_SHORT).show();
} else {
result.setText("Not Relative Prime");
Toast.makeText(MainActivity.this, "Not Relative Prime", 
Toast.LENGTH_SHORT).show();
}
}
});

Error LOG

11-22 13:00:21.854 6630-6630/com.example.jasirali.layout_elements E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.jasirali.layout_elements, PID: 6630
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.jasirali.layout_elements/com.example.jasirali.layout_elements.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2298)
        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$MethodAndArgsCaller.run(ZygoteInit.java:899)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
     Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
        at com.example.jasirali.layout_elements.MainActivity.onCreate(MainActivity.java:128)
        at android.app.Activity.performCreate(Activity.java:5937)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2251)
        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)

Questions seeking debugging help ("why isn't this code working?") must include the desired behavior, _a specific problem or error_ and _the shortest code necessary_ to reproduce it **in the question itself**. Questions without a clear problem statement are not useful to other readers. See: [How to create a Minimal, Complete, and Verifiable example](http://stackoverflow.com/help/mcve). — Joe C, Nov 22 '18 at 07:57
Please use proper indentation to make your code readable. This will also help yourself. — Henry, Nov 22 '18 at 08:00
The `relative` variable is `null`. Check if you got it via `findViewById()` — Denis Loh, Nov 22 '18 at 08:03

score 0 · Accepted Answer · answered Nov 22 '18 at 08:29

0

The relative variable is null. Check if you got it via findViewById()

This should solve the problem.

answered Nov 22 '18 at 08:29

Denis Loh

2,194
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Activity has been stopped

1 Answers1