1.15.2 How to realize the function of button

[Same here]

 @Override
    protected void init()
    {
        super.init();
        Button.IPressable onPress;
        int offsetX = (this.width - this.xSize) / 2, offsetY = (this.height - this.ySize) / 2;
        this.buttons.add(new Button(offsetX+153,offsetY+17,20,20,"start",(p_212984_1_) -> {
            this.minecraft.displayGuiScreen(this.getMinecraft().currentScreen);})
        {
            @Override
            public void onPress()
            {
                //TODO 
            }
        });

I have made a screen,I want to add a button to do something ,I used anonymous inner classes，but  whatever I write in “todo”，when I pressen the button it didn't work.Did I use the wrong method？Please help me .

[Dzuchun]

Here is an example of button from IngameMenuScreen class:

this.addButton(new Button(this.width / 2 - 102, this.height / 4 + 24 + -16, 204, 20, new TranslationTextComponent("menu.returnToGame"), (p_213070_1_) -> {
         this.minecraft.displayGuiScreen((Screen)null);
         this.minecraft.mouseHelper.grabMouse();
      }));

This works for sure, find the difference.

[Same here]

15 hours ago, Dzuchun said:

Here is an example of button from IngameMenuScreen class:

this.addButton(new Button(this.width / 2 - 102, this.height / 4 + 24 + -16, 204, 20, new TranslationTextComponent("menu.returnToGame"), (p_213070_1_) -> {
         this.minecraft.displayGuiScreen((Screen)null);
         this.minecraft.mouseHelper.grabMouse();
      }));

This works for sure, find the difference.

Excuse me, is there a more detailed example? I don't quite understand. I often use listeners in Java, but I don't understand how this button works.

[Dzuchun]

2 hours ago, Same here said:

I often use listeners in Java

Here you don't need this to execute something on button click. Listening is already handled by LWJGL (not sure), so all you need is to specify function that should be executed once button is pressed.

(p_213070_1_) -> {
  this.minecraft.displayGuiScreen((Screen)null);
  this.minecraft.mouseHelper.grabMouse(); 
}

Here is this function. This format is called lambda-expression. Check source code for more context, this code is located at IngameMenuScreen class.

[Same here]

15 hours ago, Dzuchun said:

Here you don't need this to execute something on button click. Listening is already handled by LWJGL (not sure), so all you need is to specify function that should be executed once button is pressed.

(p_213070_1_) -> {
  this.minecraft.displayGuiScreen((Screen)null);
  this.minecraft.mouseHelper.grabMouse(); 
}

Here is this function. This format is called lambda-expression. Check source code for more context, this code is located at IngameMenuScreen class.

My friend, thank you very much for your patience and help me a lot. I looked at the source code before, but I made a fatal mistake. I have been paying attention to lambda and have not used addbutton correctly. Thank you very much for your help.